UTILIZATION OF OVERRIPE DISCARDABLE FRUITS OF PINEAPPLE AND BANANA FOR JAM PREPARATION Dissertation Submitted to the Kerala University of Fisheries and Ocean Studies in partial fulfilment of the requirement of the degree of
Master of Science In Food Science & Technology
By ANUSHA V (OST-2014-24-04)
Department of Food Science and Technology Kerala University of Fisheries and Ocean Studies (KUFOS) Panangad P.O., Kochi – 682 506, India
2016
DECLARATION
I, Anusha V hereby declare that the dissertation on “UTILIZATION OF OVERRIPE DISCARDABLE
FRUITS
OF
PINEAPPLE
AND
BANANA
FOR
JAM
PREPARATION” is a bonafide record of my work carried at Pineapple Research Station, KAU, Vazhakulam, from 1st April 2016 to 31st May 2016 and this has not previously formed the basis for the award of any degree, fellowship or any other similar title of any other University or Institute.
Place : Panangad Date : 3rd Aug, 2016
Anusha V OST-2014-24-04
KERALAUNIVERSITY OF FISHERIES & OCEAN STUDIES DEPARTMENT OF FOOD SCIENCE AND TECHNOLOGY PANANGAD P.O., KOCHI 682 506, KERALA, INDIA
91-484- 2703782, 2700598; Fax: 91-484-2700337; e-mail:
[email protected]; website: www.kufos.ac.in
No.
Date: 03/08/2016
Certificate This is to certify that the dissertation entitled “UTILIZATION OF OVERRIPE DISCARDABLE FRUITS OF PINEAPPLE AND BANANA FOR JAM PREPARATION” performed under our guidance and supervision is a bonafide record of Ms. ANUSHA. V (Reg. No. OST-2014-2404), carried out at Pineapple Research Station (Kerala Agricultural University), Vazhakulam in partial fulfillment of the requirement for the award of degree of Master of Science in Food Science and Technology of Kerala University of Fisheries and Ocean Studies (KUFOS), Kochi – 682 506, India. Certified further to the best of our knowledge that this work does not form part of any other dissertation or project work on the basis of which a degree or diploma or a similar title has been awarded earlier to any candidate by any other University.
Dr. K. Gopakumar (Chairman) Professor of Eminence & Head Department of Food Science and Technology Kerala University of Fisheries and Ocean Studies Kochi – 682 506, India
Dr. P.P. Joy (Guide) Associate Professor & Head Pineapple Research Station, Vazhakulam Kerala Agricultural University, Thrissur
Dr. Sanu Jacob (Co-guide) Assistant Professor Department of Food Science and Technology Kerala University of Fisheries and Ocean Studies (KUFOS) Kochi – 682 506, India
Tel. & Fax: 0485-2260832, Mobile: 9446010905 E-mail:
[email protected] , Web: http://prsvkm.kau.in
KERALA AGRICULTURAL UNIVERSITY
PINEAPPLE RESEARCH STATION Vazhakulam, Muvattupuzha, Ernakulam, Kerala- 686 670 No. PRS/S34/16
Dated: 03.08.2016
CERTIFICATE
This is to certify that the dissertation entitled UTILIZATION OF OVERRIPE DISCARDABLE FRUITS OF PINEAPPLE AND BANANA FOR JAM PREPARATIONis an authentic record of the studies and research work carried out by Ms.ANUSHA. V (Reg. No: OST-2014-24-04), Department of Food Science and Technology, Kerala University of Fisheries and Ocean Studies (KUFOS), Kochi under our supervision and guidance for the partial fulfilment of the requirements for the award of degree of Master of Science in Food Science and Technology of KUFOS and that, to the best of our knowledge and belief, no part of this work has been presented earlier for any degree or diploma in this or any other Universities or Institutes.
Rashida Rajuva T.A Head, Food Technology Division
Dr. P. P. Joy Guide Associate professor & Head
ACKNOWLEDGEMENT
This acknowledgement note is to express my sincere gratitude to each and everyone who paved way for the successful completion of Dissertation for M.Sc. (Food Science & Technology) of Kerala University of Fisheries & Ocean Studies, Kochi. I would like to acknowledge my sincere gratitude to Dr. K. Gopakumar, Professor of Eminence & Head and Dr. Sanu Jacob, Assistant Professor, Department of Food Science and Technology of Kerala University of Fisheries and Ocean Studies, Kochi for suggesting a title for my M.Sc. dissertation. My heartfelt thanks for their constant guidance and encouragement till the end of my dissertation work. I express my deep gratitude to them for correcting my dissertation manuscript. Sincere gratitude is expressed here to Dr. P. P. Joy, Associate Professor (Agronomy) and Head, Pineapple Research Station (Kerala Agricultural University), Vazhakulam, Kerala for providing me the research facilities at his centre. I sincerely thank his colleague, Mrs. Rashida Rejuva T.A., Head, Food Technology Division for her constant support and guidance throughout my work. My heartfelt thanks to Ms. Anjana R. (Biotechnology Division), Ms. Divya B. (Food Technology Division), Mrs. Soumya K. K. and Ms. Aswathy C. (Biochemistry Division) and other staff of PRS, Vazhakulam for their needful assistance and technical support out of their busy schedule. Thanks to my adorable Parents for their constant encouragement, love and support given to me throughout my life including my M.Sc. degree programme at KUFOS. My loving brother Arjun V too deserves an appreciation and thanks here for helping me with material purchases for my experimentation and their transportation during my dissertation work. Not the least, my M.Sc. classmates deserves an admiration for their warm camaraderie rendered to me during our 2 years of M.Sc. Food Technology programme. Lastly, I bow my head to Almighty God for the constant blessings bestowed on me throughout my life, without which I am nothing.
ANUSHA. V
DEDICATED TO MY BELOVED PARENTS AND TEACHERS
TABLE OF CONTENTS
Chapter 1
2
3
4
Content
Page No.
INTRODUCTION 1.1 Fruits
15
1.2 Pineapple
15
1.3 Banana
18
1.4 Production of Pineapple and Banana
21
1.5 Jam
22
1.6 Objectives
24
REVIEW OF LITERATURE 2.1 Jam
26
2.2 Diabetic Friendly Low-calorie Jam
32
2.3 Sensory Evaluation
36
MATERIALS AND METHODS 3.1 Materials
41
3.2 Methods
41
3.3 Instruments Used
52
3.4 Ingredients and Products
53
RESULTS AND DISCUSSION 4.1 Physicochemical Analysis
55
4.2 Sensory Evaluation
69
4.3 Comparison of normal and sugar free jam
74
5
SUMMARY AND CONCLUSION
77
6
REFERENCES
80
LIST OF TABLES
Table No.
Particulars
Page No.
1.1
Taxonomical classification of Pineapple
16
1.2
Nutritional value of Pineapple (per 100 g)
17
1.3
Chemical composition of Pineapple (%)
17
1.4
Taxonomical classification of Banana
19
1.5
Nutritional value of Banana (per 100 g)
20
1.6
Chemical composition of Banana (%)
20
1.7
FPO specification of jam (per 100g)
22
3.1
Ingredients and amount used for normal and sugar free jam
42
3.2
Proportion of pulp used for jam preparation
43
3.3
Treatment details of diabetic friendly jam
43
4.1
pH and Titratable acidity of fruits
55
4.2
TSS of fruits
57
4.3
Moisture content of fruits
58
4.4
Total, reducing and non-reducing sugar content of fruits
59
4.5
pH of jam samples
60
4.6
Titratable acidity of jam samples
60
4.7
Ascorbic acid content of jam samples
61
4.8
TSS content of jam samples
62
4.9
Moisture content of jam samples
63
4.10
Ash content of jam samples
63
4.11
Total sugar content of jam samples
64
4.12
Reducing sugar content of jam samples
65
4.13
Non-reducing sugar content of jam samples
66
4.14
pH and Titratable acidity of diabetic friendly jam
67
Table No.
Particulars
Page No.
4.15
Ascorbic acid content of diabetic friendly jam
68
4.16
Moisture content of sugar free jam
69
4.17
Sensory score of flavour, taste and sweetness of jam
70
4.18
Sensory score of colour, texture and overall acceptability of jam
71
4.19
Flavour, taste and sweetness score of sugar free jam
73
4.20
Colour, texture and overall acceptability score of sugar free jam
74
LIST OF FIGURES
Figure No.
Particulars
Page No.
1.1
Production of Pineapple in Kerala during 2013-14
21
1.2
Production of Banana in Kerala during 2013-14
21
3.1
Over-ripe fruits used for jam preparation
41
3.2
Score Sheet Used for Sensory Evaluation of Jam
51
3.3
pH Meter
52
3.4
Desiccator
52
3.5
Electronic weighing balance
52
3.6
Hot air oven
52
3.7
Water bath
52
3.8
Hand refractometer
52
3.9
Digital refractometer
52
3.10
Muffle Furnace
52
3.11
Burettes
52
3.12
Blender
52
3.13
Ingredients of normal jam
53
3.14
Normal jams
53
3.15
Ingredients of diabetic friendly jam
53
3.16
Diabetic friendly jam
53
4.1
Ascorbic acid content of fruits
56
4.2
TSS of Fruits
57
4.3
Ash Content of Fruits
58
4.4
Total Sugar (TS), Reducing Sugar (RS) and Non-reducing Sugar (NRS) Content of Fruits
59
4.5
TSS of 25:75 (Pineapple:Banana) and Individual Jam samples
62
4.6
TSS and Total Sugar of Pineapple:Banana (75:25 & 50:50) Jam Samples
64
4.7
Reducing Sugar of Individual Jam Samples
65
4.8
Non-reducing Sugar of Different Proportion of Jam Samples
66
4.9
TSS Content of Sugar Free Jam
68
Figure No.
Particulars
Page No.
4.10
Ash Content of Sugar Free Jam
69
4.11
Sensory values of different proportions of pineapple and banana jam Average sensory score for sugar free jam prepared using 50:50
73
4.12
74
(Palayankodan), 75:25 (Njalipoovan) and 75:25 (Karpooravalli) 4.13
Comparison of overall acceptability score of 75:25 (Karpooravalli) sugar and sugar-free Jam
75
ABBREVIATIONS
Abbreviation
Full Form
viz.
videlicet
i.e.
that is
vit.
vitamin
°Brix
Degree Brix
sp.
Species
g
Gram
mg
Milligram
µg
Microgram
kcal
Kilocalorie
IU
International Unit
etc.
ex cetera
°C
Degree celcius
cv
Cultivar
cell/g
Cell per garm
min
Minute
kg
Kilogram
kcal/g
Kilocalorie per gram
w/w
Weight by weight
g/kg
Gram per kilogram
ml
Millilitre
N
Normality
Pb
Lead
mg/g
Milligram per gram
h/hr
Hour
eg.
Example
TSS
Total soluble solids
AOAC
Association of official analytical chemists
var.
Variety
FPO
Fruit products order
ABSTRACT
A study was done to utilize over ripe discardable fruits of pineapple and banana for jam preparation. Three over ripe perishable varieties of banana: Palayankodan, Njalipoovan and Karpooravalli and a Vazhakulam pineapple variety was used for jam preparation. Pineapple and banana were mixed in the ratios of 100:0, 75:25, 50:50, 25:75 and 0:100 respectively. This combination was maintained same for all banana varieties. In total there were 13 treatments prepared for this experiment. After jam preparation, various quality parameters were analysed for all treatments that included physical, chemical and sensory properties of jam. The sensory properties were evaluated by a sensory panel. The results indicated an overall consumer acceptance for pineapple: banana treatments with combination ratio of 50:50 (Palayankodan); 75:25 (Njalipoovan) and 75:25 (Karpooravalli). The same treatment combinations were further utilized for sugar-free jam preparation by replacing sugar with sucralose and sorbitol. The quality characteristic of both sugar and sugar-free jams were comparable, however, higher consumer preference was for sugar included jams. The overall consumer acceptance was higher for 75:25 (Njalipoovan) in sugar-free jam category. Conclusively, over ripe discarded fruits can be efficiently used for making value-added products like jam.
1. INTRODUCTION
1.1. FRUITS Fruits occupy a significant proportion and position in human diet. The word ‘fruit’ originate from the Latin word ‘fructus’ which means ‘enjoyment of produce or harvest’. Generally, a fruit is a seed-bearing structure found in angiosperms formed from the ovary after flower fertilisation. In common language, fruit normally means the fleshy seed-associated structures of a plant that is either sweet or sour, and edible in the raw and processed forms. Fruits are considered health capsules as they are known to possess rich source of carbohydrates, minerals, vitamins, dietary fibres and antioxidants. They are very low in fats and proteins but high in sugar as they contain large amount of glucose, fructose and sucrose. Other constituents such as organic acids, phenolic substances, volatile substances and minerals may be present and they play an important role in the chemical reactions which occur during processing and storage (Ong et al., 2012). 1.2. PINEAPPLE Pineapple (Ananas comosus L. Merr) is a tropical fruit, named from the similarity of the fruit to a pine core. The word ‘pineapple’ in English was first recorded in 1938 to desc ribe the reproductive organs of conifer trees. When European explorers discovered this tropical fruit in America, they called them “pineapples”. Deciphering its binomial nomenclature, the word ananas comes from the Tupi word nanas, meaning “excellent fruit”, and comosus, which means ‘tufted’ refers to the stem of the fruit. According to Oyeleke et al. (2013) pineapple fruit is a compound (multiple) fruit that develops from many small fruits fused together around the central core. Its pulp is juicy and fleshy with the stem serving as a supporting fibrous core. 1.2.1. Origin Pineapple is native to Central and South America specifically Southern Brazil and Paraguay (Fernandez et al., 2008). In 1493, Christopher Columbus is credited with discovering the pineapple on the island of Guadeloupe, although the fruit had long been grown in South America (Abalaka et al., 2013). He called it ‘pina de Indus’ meaning pine of the Indians. South American Guarani Indians cultivated pineapples for food and they called i t “nana”, meaning ‘excellent fruit’. Another explorer, Magellan is credited with finding pineapples in Brazil in 1519, and by 1555, the luscious fruit was being exported with gusto to England. It
15
soon spread to India, Asia and West Indies. Although, the pineapple thrived in Florida, it was still a rarity for most Americans. 1.2.2. Family Bartholomew and Maleieux (1994) point out that pineapple belongs to the family Bromeliaceae which encompasses about 50 genera and 2000 species mostly epiphytic. It is a member of the tropical plants called the bromeliads and is the only edible species of that family. It is grown in hot regions all around the world. It is not a single fruit but a composite mass of between 100 and 200 berrylike fruitless that formed together into one compact fruit. The taxonomical classification of pineapple is given in Table 1.1. Table 1.1. Taxonomical classification of Pineapple Kingdom
Plantae
Order
Poales
Family
Bromeliaceae
Subfamily
Bromeliodeae
Genus
Ananas
Species
Ananascomosus
1.2.3. Nutritional Value According to Samson (1986) pineapple mainly contains water, carbohydrates, sugars, vitamin A, vitamin C and β carotene. It contains low amounts of protein, fat, ash, fiber and antioxidants namely flavonoids in addition to citric and malic acid and moderate amounts of ascorbic acid (Tochi et al., 2008). MacDonald and Low (1996) stated that pineapple also helps several enzymes present in the body to produce energy as it contains magnesium and vitamin B1 which are essential for the normal functioning of some enzymes. It is an excellent source of antioxidant vitamin C which is required for the collagen synthesis in the body. Pineapples can be consumed fresh, cooked, juiced or preserved. Debnath et al. (2012) stated that, several essential minerals exist in pineapples, including manganese, a trace mineral instrumental to the formation of bone, as well as the creation and activation of certain enzymes. It also includes another trace mineral copper. An approximate nutritional value of pineapple is given in Table 1.2.
16
Table 1.2. Nutritional value of Pineapple (per 100 g) Energy
48 kcal
Folate (vit. B9)
15.00 µg
Water
80-87 g
Vitamin C
47.80 mg
Carbohydrates
13.12 g
Calcium
13.00 mg
Fat
0.12 g
Iron
0.28 mg
Protein
0.54 g
Magnesium
12.00 mg
Thiamine (vit. B1)
0.10 mg
Phosphorus
8.00 mg
Riboflavin (vit. B2)
0.03 mg
Potassium
115.00 mg
Niacin (vit. B3)
0.50 mg
Manganese
0.90 mg
Panthothenic acid (vit. B5)
0.21 mg
Sodium
1.00 mg
Vitamin B6
0.11 mg
Zinc
0.10 mg
1.2.4. Chemical Composition According to Dull (1971) pineapple composition has been investigated mainly in the edible portion. Pineapple contains 81.2-86.2% moisture and 13-19% total solids, of which sucrose, glucose and fructose are the main components. Carbohydrates represent up to 85% of total solids whereas fiber makes up 2-3%. Of the organic acids, citric acid is the most abundant. The pulp has very low ash content, nitrogenous compounds and lipids (0.1%). 25-30% of nitrogenous compounds are true protein. Out of this proportion, 80% has proteolytic activity due to a protease known as Bromelain. Fresh pineapple contains minerals such as calcium, chlorine, potassium, phosphorus and sodium. Chemical composition of fresh pineapple is given in Table 1.3. Table 1.3. Chemical Composition of Pineapple (%) Total Soluble Solids (TSS) °Brix
10.80 – 17.50
Titratable Acidity (as Citric acid)
0.60 – 1.62 81.20 – 86.20
Moisture
0.30 – 0.61
Fiber Lipids
0.20 0.20 – 2.50
Pigments (ppm carotenes) Total Aminoacids
0.33 0.05 – 0.12
Total Nitrogen Protein
0.18
Soluble Nitrogen
0.08 0.3 0 – 0.42
Ash 17
1.2.5. Vazhakulam Pineapple Pineapple has been commercially grown in Vazhakulam area for more than 50 years. It is an excellent fruit for fresh consumption. Vazhakulam area is ideally suited for the production of pineapple for table purpose. Planting is done in almost all months, except during the heavy monsoon days. Hence, fruits are available round the year. Vazhakulam is considered as the biggest pineapple market in India from where the fruit is being transported to all the South Indian as well as North Indian states. It is grown in the districts of Ernakulam, Kottayam, Pathanamthitta and the low elevation areas of Idukki district in Kerala. It is the centre of pineapple trade in Kerala and India. Vazhakulam pineapple was registered as Geographical Indication (GI) No. 130 under Agricultural – Horticultural product at the GI Registry, Chennai on 4th September 2009. GI registration is the process of endorsing brand protection under WTO guidelines to the producers of any product known for quality and marketed in the label of a geographic area. Vazhakulam pineapple locally known as ‘Kannara’ is a Mauritius variety coming under the queen group of the species Ananas comosus. The plant is about 85-90 cm height, leaves spiny, gives yield within 12 months. The average fruit weight is 1.2-1.5 kg. The fruit has a pleasant aroma, slightly conical in shape, fruit ‘eyes’ deeply placed, fruit flesh is crispy and golden yellow in colour, juice is sweet with 14-16 °Brix and its acidity is 0.50-0.70% (Joy, 2013). It is unique in aroma, flavour and sweetness due to its high sugar content and low acidity. The fruit withstands post harvest handling damages and long distance transport. 1.3. BANANA Banana (Musa sp.) is an important fruit crop of tropical and sub-tropical regions of the world. It is the most widely cultivated and consumed fruit where they constitute a major staple food crop for millions of people. The term banana was introduced fro m the Guinea coast of West Africa by the Portuguese from the Wolof word ‘banaana’ (Purseglove, 1975). Banana is a common term embracing a number of species or hybrid in the genus Musa of the family Musacaea (Zhang et al., 2005) and cultivated mainly for its fruit. Most people consume banana fresh, steamed or boiled. Generally, it is believed that all the edible bananas are indigenous to the warm moist region of tropical Asia comprising India, Burma, Thailand and Indo-China (Tajuddin et al., 1996). 1.3.1. Origin It is believed that the banana originated in the hot, tropical regions of southern Asia. It is native to the South-East Asia, in the jungles of Malaysia, Indonesia and Philippines. Edible
18
bananas were originated in the Indo-Malaysian region reaching to northern Australia. They were known only by hearsay, in the Mediterranean region in the 3rd Century B.C., and are believed to have been first carried to Europe in the 10th Century A.D. Early in the 16th Century, Portuguese mariners transported the plant from the West African coast to South America. 1.3.2. Family The genus Musa was traditionally classified into five species (Ingentimusa, Australimusa, Callimusa, Musa and Rhodochlamys), but these have recently (2002) been reduced to three (Zhang et al., 2005). There are 25 – 80 species in the genus Musa, (Tock et al., 2010). Musa is one of three genera in the family Musaceae which include banana and plantain. Banana is a general term embracing a number of species or hybrid in the genus Musa of the family Musacaea. Table 1.4. Taxonomical classification of Banana Kingdom
Plantae
Class
Liliopsida
Order
Zingiberales
Family
Musaceae
Genus
Musa
Species
M. acuminate, M. balbisiana
1.3.3. Nutritional Value Banana fruits are wholesome and fairly balanced source of nutrient containing various mineral salts, vitamins and high amount of carbohydrates with little oil and protein (Simmonds, 1966; Ketiku, 1973; Ahenkora et al., 1997). It has a special place in diet with low fat and cholesterol but high in calories. About 100g of banana provides about 100 calories which is 50% more energy released by fruits like apples and citrus (Anon, 2000). These are considered nutritive with high content of vitamins A and C but poor in vitamin B (Margard and Briav, 1979). Generally they contain a considerable amount of mineral elements and could therefore serve as a good source of mineral supplement in human/animal diet. This fruit is rich in minerals (potassium, magnesium and phosphorus), dietary fibre, and various antioxidants such as vitamin A, vitamin C and β carotene (Kanazawa and Sakakibara, 2000).
19
Fresh bananas have high water content (78-80%), with the dry matter consisting mainly of starch (72%) which turns into simple sugars during ripening. The remaining material has a low content of protein, vitamins and inorganic nutrients. Potassium is the most abundant mineral with estimated values in the range of 4.10-5.55 mg per 100 g dry weight (Goswami and Borthakur, 1996). Bananas are identified as relatively rich in pyridoxine (vitamin B6) (Leklem, 1999). At maturity bananas are relatively rich in vitamins A (carotene), B (thiamine, riboflavin, niacin, B6) and C (ascorbic acid) and in potassium, phosphorus and magnesium. Table 1.5. Nutritional value of Banana (per 100 g) Energy
89 kcal
Vitamin C
12 mg
Water
61-70 g
Folate (vit. B9)
20 µg
Carbohydrates
27-36 g
Calcium
5-8 mg
Fat
0.20 g
Iron
0.50 mg
Protein
1.10 g
Magnesium
530 µg
Thiamine (vit. B1)
45 µg
Phosphorus
30 mg
Riboflavin (vit. B2)
55 µg
Potassium
395 mg
Niacin (vit. B3)
0.50 mg
Manganese
530 µg
Vitamin A
540 IU
Sodium
0.10 mg
Vitamin B6
370 µg
Zinc
220 µg
Vitamin E
270 µg
Iodine
3 µg
1.3.4. Chemical Composition Banana pulp comprises 75% water, is among the most calorie- rich of non-oil fresh fruits. It contains approximately 20 g of carbohydrates in total per 100 g of fresh pulp, out of which fibre 2 g per 100 g fresh weight. Table 1.6. Chemical Composition of Banana (%) Moisture
61-70
Fiber
3.00
Lipids
0.40
Total Aminoacids
3.00
Fatty Acids
1.00
Protein
1.30
Ash
0.80
20
1.4. PRODUCTION OF PINEAPPLE AND BANANA Pineapple and banana are popular tropical fruits of Kerala which are produced abundantly round the year. The annual production of banana and pineapple in Kerala are 5.3 lakh tonnes and 0.75 lakh tonnes (Agricultural Statistics 2013-14, Govt. of Kerala) respectively. Major varieties of pineapple cultivated in Kerala include Kew, Mauritius and MD-2 while banana include Nenthran, Njalipoovan, Palayankodan, etc. Production of pineapple and banana in Kerala are given in the following figures. (Fig.1.1 and Fig.1.2).
Fig. 1.1. Production of Pineapple in Kerala during 2013-14 Out of the total production of pineapple, about 71% of production is in Ernakulam district with a production of 53721 tones. Out of the total production of banana, about 28% is from Palakkad and stands 1st position with a production of 147.29 thousand tones.
Fig. 1.2. Production of Banana in Kerala during 2013-14 21
Although the production is massive, high postharvest losses have been observed in these fruit crops due to their high perishability and mishandling. These losses are particularly seen when there is a glut in their production with little scope on their postharvest processing and preservation. The fruits are known to possess high nutritional value, sugar level with appreciable flavour. They are soft and juicy also. The market value of these fruits is also reduced due to the glut during the harvesting time. Hence, value addition through processing would be the only effective tool for economic utilization of these fruits. Fruits discarded from wholesale as well as retail market can be utilized for this purpose. The shelf-life of fruits can be extended by processing it to different food products like jam, jelly and squash. Jams are more economical and have more shelf-life compared to other products. 1.5. JAM Jam is a product made from any fruit, which is used as a preservation method for extending the shelf life of fruits. It is made by boiling fruit and sugar to give high solid products. It can be prepared from one kind of fruit or from two or more kinds. The main ingredients used in jam preparation are fruit pulp, sugar, pectin and citric acid. The total soluble solids (TSS) content of jam should not be less than 68% (FPO, 1955). One important feature of jam is the high acidity which prevents the growth of food poisoning bacteria and also helps maintain the colour and flavour for most fruits. Desrosier and Desrosier (1978) defined jam as a semisolid food made from not le ss than 45% (by weight) fruit and 55% (by weight) sugar. This substrate is concentrated to 65% or above soluble solids. Flavouring and colouring agents may be added. Pectin and acid may be added to overcome the deficiencies that occur in the fruit itself. The FPO (1955) specification of jam is given in Table 1.7. Table 1.7. FPO specification of jam (per 100g) Parameters
Specification
TSS
68.5%
Fruit pulp
45%
Citric acid
0.5-0.6%
Optimum pH
3.35-3.70
Acidity
0.5-0.7%
High sugar content of jam may cause diabetic problems. Kerala is the diabetic capital of India with a prevalence of diabetes as high as 20%, double the national average of 8% 22
(Mohan et al., 2007).Several studies from different parts of Kerala support the high prevalence of diabetes. The chances of diabetes can be reduced by using sugar-free jam. Sugar free or diabetic friendly jam can be prepared by replacing artificial sugar in the optimum quality jam with non-calorie sweeteners (like sucralose, sorbitol, etc.). Low sugar or diabetic jams were originally developed for diabetics and people with specific health problems. The food industry has been confronted with a new challenge in order to satisfy the consumers that is the development of low-calorie products with acceptable sensorial characteristics and competitive prices. Nowadays, consumers demand for lowcalorie products have significantly risen in an attempt to alleviate the health problems, to reduce or stabilize the body weight, or because they are concerned about a healthy diet. The Pineapple Research Station (PRS) at Vazhakulam was established on 2 nd January 1995 to give research and development support to pineapple farmers. Since then, this research centre of the Kerala Agricultural University (KAU) has been steadily growing and serving as a subvention to the pineapple growers of the state and the country as well. The research centre strives to become the ultimate authority and provider of excellent quality technology, products and services in the pineapple sector through concerted research and development efforts sustained by best human resource and infrastructure development. The centre has developed scientific technology for the commercial cultivation of Kew and Mauritius varieties of pineapple, including pure cropping, intercropping in rubber and coconut plantations and in reclaimed paddy lands. The present work deals with the utilization of over ripe fruits of pineapple and banana for diabetic jam preparation. Fruits discarded at wholesale and retail market level is utilized for this. Three highly perishable varieties of Banana (Palayankodan, Njalipoovan and Karpooravalli) together with over ripe Vazhakulam pineapple (Mauritius var.) were used in different proportions for preparation of jam. From these proportions, best 3 combinations from each category were selected. Diabetic jam was prepared using these 3 combinations and quality parameters like nutritional value, shelf life and consumer acceptance by organoleptic methods were evaluated for these samples. Physicochemical as well as sensory parameters of diabetic friendly jam were compared with the normal jam samples prepared.
23
1.6. OBJECTIVES 1.
To prepare a value-added product from overripe discarded fruits of pineapple and banana.
2.
To study the physical, chemical and sensory properties of the prepared jam.
3.
To select the ideal proportion of pineapple and banana mix for optimum quality jam preparation.
4.
To prepare diabetic friendly low-calorie jams replacing sugar with sucralose and sorbitol.
5.
To study and compare the physical, chemical and sensory properties of diabetic friendly jam with respect to normal jam containing sugar.
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2. REVIEW OF LITERATURE
Jam is a common product prepared using fruits. It is one of the best method to preserve fruits and thus available round the year. So many studies were conducted in this field based on the preparation of jam from different fruits, their storage studies, replacement of sucrose with other sweeteners etc. Some of these works are discussed below. 2.1. JAM Jam is a product made with whole fruit, cut into pieces or crushed. The fruit is heated with water and sugar to activate the pectin in the fruit. The end product is less firm than jelly, but still holds its shape. Jam is a product made by boiling fruit pulp with sufficient quantity of sugar to a reasonably thick consistency, firm enough to hold the fruit tissues in position. Apple, sap ota, papaya, plums, mango, grapes, jack, pineapple, banana, guava and pears are used for preparation of jam. It can be prepared from one kind of fruit or from two or more kinds. In its preparation about 45% of fruit pulp should be used for every 55% of sugar. According to Bureau of Indian Standards (BIS) and Prevention of Food Adulteration (PFA) specifications, jam should contain more than 68.5% TSS and at least 45% fruit (The Prevention of Food Adulteration Rules, 1955; Santanu and Shinhare, 2010), whereas, the Codex Alimentarius Commission specifies that the finished jam should contain more than 65% TSS. Berolzheimer (1969) reported that a good jam has the following attributes: even consistency without distinct pieces of fruit, good fruit flavour, bright colour, semi-gelled texture, easy to spread and have no free liquid, because it is neither solid nor a liquid. UNE regulation (1974) defined jam as product formulated from a minimum fruit content of 40% (30% for citric) and a final soluble solid content of 45°Brix. Moreover, some additives such as citric acid or gelling agents, commonly pectin, can be added. In jam gel formation occurs only within a narrow range of pH values. Optimum ph conditions are found near 3.2 for gel formation. The optimum solids range is slightly above 65%. It is possible to have gel formation at 60% solids, by increasing the pectin and acid levels. The quantity of pectin required for gel formation id dependent upon the quality of pectin. Ordinarily, slightly less than 1% is sufficient to produce a satisfactory structure (Desrosier and Desrosier, 1978). 26
According to Egan et al. (1981) jam is a fruit preserve with a stable shelf-life that depends on high sugar content (68 to 72%) combined with the fruit acidity that prevents microbial invasion and growth. It is a complex product that requires precise balance between sugar level, acidity and pectin content of fruit boiled together to produce a gel on cooling. Street (1991) stated that jam is produced by boiling fruit with sugar until the total soluble solvents reaches 69.5%. But bakery purposes a stiffer jam of about 72% solids is often used. The solids content can be monitored by using Refractometer. Broomfield (1996) reported that jams made from different types of fruits are a popular food items among the local population. It is usually prepared from cooked fruit or vegetable, sugars, citric acid and pectin. May (1997) stated that in traditional jam manufacture, all the ingredients are mixed in predetermined proportions and the mix is concentrated by applying thermal treatments at normal or reduced pressure to reach the final soluble solid content. This process leads to thick consistency, destroys fruit enzymes, extracts some of the pectin from the fruit and concentrates the product to a point where as a result of its acidity and reduced water activity becomes self-preserving. This process induces undesirable changes in colour, texture, nutritive value and flavour, due to prolonged high cooking process. Fruits with naturally high pectin content including citrus fruits such as limes and lemons, berry fruits such as cranberries, loganberries, redcurrants and blackcurrants and free top fruits such as quinces and apples including apricots were commonly used in producing jam (Burkill, 1997). Sugar constitutes more than 40% of total weight and 80% of total solids in jam (Lal et al., 1998; Santanu and Shinhare, 2010). Commercial jam usually has an extremely variable composition. The ingredients affect the jam quality in terms of both subjective (sensory) and objective (textural and rheological) attributes. Ihekoronye (1999) stated that jam is produced by taking mashed or chopped fruit or vegetable pulp and boiled with sugar and water until a suitable consistency is obtained. Many tropical fruits have been used in the production of jam. According to Thomas et al. (2000) in jam production, pectin can be obtained from fruit peels like orange which increases the dietary fibre of the end product and also reduces blood sugar when consumed.
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Jam is a traditional food product, commonly consumed as dessert, bread spread, and cake toppings. It is light to dark brown in colour, thick and spreadable in consistency, with creamy flavour and provides a good source of energy, vitamins and minerals. The jam quality are affected during the storage period based on the quality of the raw material used, recipe selection, processing conditions, method of preservation and storage conditions (Redalen and Haffner, 2002; Haffner et al., 2003; Wicklund et al., 2005; Kvikliene et al., 2006). Jawaheer et al. (2003) investigated the effects of storage of fresh fruit of guava and the processing into jam and juice followed by storage, on the ascorbic acid content of guava. Results showed that processing led to an overall decrease of 20.4 percent for juice and 62.5 percent for jam. According to Morris (2004) jam is a preparation consisting of whole fruit boiled with sugar, having a consistency firm enough to meet the demands of confectioners. All jam shall contain not less than 68.5% total soluble solids. Sugar is necessary to give strength of the pectin-sugar-acid gel. It is assumed that about 3 to 5% total weight of jam is represented by sugar derived from the fruit. Fruit pulp, pectin, sugar and acid are contained in jam as it is an intermediate moisture food (Santanu et al., 2007). Fugel et al. (2005) reported that jam is a mixture of sugars, pulp and a pure drop of one or more kinds of fruit and water brought to a suitable gelled consistency. Shivhare et al. (2007) reported that jam is an intermediate moisture food containing fruit pulp, pectin, sugar and acid. The effect of sugar and pectin concentration, pH, shear rate and temperature on the time dependent rheological properties of pineapple jam was studied using rheometer. Pineapple jam exhibited thixotropic behaviour. Shear stress of pineapple jam at a particular time of shearing depended on the shear rate, temperature and composition. Singh et al. (2009) prepared jams from overripe fruits in different combinations and investigated for various characteristics. The different combinations differed significantly among each other and had acceptable microbial and organoleptic qualities. The use of different combinations of fruit pulps having different °Brix: acid ratios affected the yield of jams. There were deviations in yields of jams prepared, as against their calculated/expected yields. The °Brix of jams were varied, but were not affected significantly either by storage or interactions of storage and fruit pulp(s) combinations in jams. Other biochemical characteristics varied as a result of storage and interactive effect in jams, except for total sugars which did not change significantly in storage. Colour intensity of these jams ranged from 12.48 to 35.84. Thus pulp combinations gave differences in natural colours of jams. 28
Shakir et al. (2009) conducted comparative study on mixed fruit jam of apple and pear pulp, incorporated within the ratios 50:50, 60:40, 40:60, 100% apple and 100% pear. All the jam samples were stored in sterilized glass jars and evaluated physicochemically for ascorbic acid, acidity, pH, total soluble solids, reducing sugars and non-reducing sugars for an interval of 15 days during three months storage period. All the samples were significantly different during storage. A decrease was observed in ascorbic acid from 17.40mg/100 to 9.19mg/100g, pH 3.64 to 3.22 and non-reducing sugars 46.00% to 16.69%. While increase was noted in % acidity from 0.60 to 0.78%, reducing sugars 16.55 to 47.30% and TSS 68.5 to 71.2°Brix during evaluation. According to Usman and James (2009) jam is a product made from whole fruit, cut into pieces or crushed. The fruit is heated with sugar and water to activate the pectin in the fruit. Jam varies in their nutritional and organoleptic properties as a result of different process technology and types of fruit and vegetable used. Ashaye and Adeleke (2009) studied the quality attributes of stored Roselle jam from dark and light red varieties were investigated. The processed jams were stored at ambient and cold temperatures. At two weeks interval they were evaluated for pH, titratable acidity, vitamin C, ash, dry matter, moisture content and sensory properties for a period of six weeks. pH of stored Roselle jam was more pronounced at ambient temperature. The moisture content of Roselle jam from dark-red Roselle Calyx under cold storage was significantly higher than other jam samples at 2 nd, 4th and 6 weeks. The dry matter content of stored jams was less than 72% with Roselle jam processed from light red variety and stored under cold temperature being significantly higher than other jam samples. Titratable acidity increased with increase in period of storage in respective of storage temperature. The ash contents decreased significantly with increase in storage period. Vitamin C at ambient temperature for both light red and dark red Roselle jam was significantly lower than the cold temperature. The sensory scores of Roselle jam prepared from both varieties were generally high. Paul (2010) explains the importance of ingredients of jam. In his study all types of jam contain four essential ingredients such as fruit, pectin, acid and sweeteners. Fruit provides unique flavour and characteristic colour as well as some pectin and acid. Pectin is found naturally in fruits and is the ingredient, when combined with sugar or other sweetness (not artificial sweeteners), that causes the fruit to gel. Pectin is concentrated in the skins and cores of fruits. Acid is necessary for gel formation and flavour. Fruits naturally contain acid, but the amount of acid varies with the fruit and degree of ripeness. Sugar is essential to help form the gel and contributes to flavour and taste. The type of sugar us ed in receipes is 29
granulated white sugar. The amount of sugar must be in proper proportion with pectin and acid to make a good gel. Basu et al. (2011) reported that jam is a product of intermediate moisture that is prepared using the pulp of fruits, sugar, pectin, acid and other ingredients that allow the conservation of such products for long periods of time, which allows the association of fruits to create new flavours. Patel and Naik (2013) prepared blended jam using banana cv. Grand Naine and pineapple cv. Queen pulp were mixed in proportions as per treatments and processed into jams with four repetitions. Physicochemical as well as organoleptic properties of blended jam were compared with sole banana and pineapple jam. The jams were studied at an interval of two months up to 12 months i.e. 0, 2, 4, 6, 8, 10 and 12 months of storage period. Overall results of jam prepared from banana: pineapple 25:75 as well as 50:50 proportions were equally best in higher level of chemical constituents, viz. total soluble solids, total sugars and reducing sugars with lower level of non-reducing sugars. Proportion of 0:100 and 25:75 were highest in respect to acidity and ascorbic acid content. All chemical constituents were found increasing up to 12 months except non-reducing sugars and ascorbic acid which were decreasing with storage period. The lowest retention was found in sole banana jam. Ajenifujah and Aina (2011) investigated the possibility of producing jam from black-plum and to evaluate the physicochemical properties, nutritional properties and consumer acceptability of the product. Physicochemical analyses of black-plum jam showed that it had soluble solids of 68.0 ± 0.71 °Brix, 24.22 ± 0.08% reducing sugar, pH of 3.42 ± 0.03 and titratable acidity 0.34 ± 0.01%. Proximate analysis of jam showed nutrient values of crude protein 4.23 ± 0.03%, crude fibre 1.0 ± 0.03%, ash 4.30 ± 0.02%, crude lipid 2.43 ± 0.03%, carbohydrate 68.1 ± 0.28%, sodium 0.28 ± 0.01mg/100g, potassium 1.42 ± 0.01mg/100g, calcium 0.97 ± 0.01mg/100g, moisture 21.65 ± 0.03% and dry matter 78.36 ± 0.33%. According to Igual et al. (2013) in jam manufacturing, the fruits and sugar are mixed in similar proportions. The mixed product is then cooked to produce a delicious substance that possesses sufficient storage capabilities. Using extreme thermal treatment, the mix is concentrated to acquire the necessary final total soluble solid content. Eke-Ejiofor and Owuno (2013) studied the physicochemical properties of jam prepared from jackfruit. The proximate composition and sensory properties were investigated and pineapple jam was used as a control. Jackfruit jam was produced using the traditional open pan method. Proximate analysis showed protein content ranging from 0.19 to1.12, ash from
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0.27 to 1.50, vitamin C from 0.0037 to 0.0099, total acid from 0.054 to 0.313, pH from 3.35 to 5.57 and °Brix from 23 to 70%. Patil et al. (2013) made an attempt to find out the possibilities of mixing guava and sapota for making jam. Guava and sapota pulp was blended in the ratios of 100:0, 90:10, 80:20, 70:30 and 60:40 respectively to prepare blended jams. The treatment of 60% guava pulp and 40% sapota pulp showed significantly less titratable acidity (1.05%), higher TSS (74.2°Brix) and total sugar (67.28%). Among the blended jams, the score for colour (8.64), flavour (8.97), taste (8.12) and overall acceptability (8.78) was judged in the treatment 60% guava pulp and 40% sapota pulp. This treatment was more in red colour. Fasogbon et al. (2013) investigated the influence of 50 °Brix sugar and 47:3% w/w sugar/salt solutions on the quality of jam produced. Pineapple slices were osmotically dehydrated (4 hr), oven dried (60°C, 27 hr), and rehydrated at 90°C for 15 min and at room temperature (RT) for 6 hr. Jams were made from dried pineapple slices (with or without osmotic dehydration), fresh pineapple and compared with commercial pineapple jam. Chemical and sensory properties of the jam were conducted. Osmotic dehydration contributed to the titratable acidity values, rehydration temperature had no significant effect on total soluble solid of the samples dehydrated in sugar/salt solution, also the moisture content increased as the rehydration temperature was increased. Osmotic dehydration of fruits prior to drying had effect on the retention of the vitamin C and protected reducing sugar from being lost. Panellist revealed that jam samples produced from pineapple dehydrated in sugar solution and rehydrated at room temperature were most preferred. Wani et al. (2013) studied on variations of sugar in jam and to find out the best treatment for maximum storage period. The experiment comprised of five levels of addition of sugar and data obtained was analyzed by completely randomized design. Results obtained fro m study showed that treatment 4 (1000g pulp + 1150g sugar) possessed an ideal value of total soluble solids (TSS), pH, acidity, moisture, ascorbic acid, iron and overall acceptability at 0, 20, 40 and 80 days of storage. These seven parameters show that th e quality of karonda jam obtained by incorporating 1150g of sugar was of good texture and quality. Chauhan et al. (2013) made an attempt to utilize the residual coconut pulp left in the tender coconuts after removal of coconut water. The coconut pulp was mixed with pineapple pulp in different proportions to increase the acceptability of the jam. An increase in the level of coconut pulp was found significantly increase the fat content as well as Na, K and Ca contents in the jam. Texture profile analysis rev ealed a significant decrease in hardness whereas adhesiveness, springiness, cohesiveness, gumminess and chewiness increased significantly with an increase in the level of coconut pulp in the jam affecting its setting 31
quality. The jam containing 75% tender coconut pulp and 25% pineapple pulp showed maximum sensory acceptability for the mixed jam. The jam prepared at optimum conditions of coconut and pineapple pulp showed a good sensory acceptability after 6 months of storage at 28±2 and 37°C storage conditions on the basis of physicochemical and sensory attributes. Pavlova et al. (2013) evaluated the quality properties of raspberry and peach jams during storage. Jams were prepared with a reduced amount of sucrose, citric acid and lowesterified pectin with the addition of calcium ions in the form of calcium citrate. Physicochemical parameters such as total dry matter, soluble solids, sugars, total acids, pH, vitamin C, fats, proteins and ash after storage of 15 to 90 days were tested. The jams were exposed to microbiological analysis too. Results showed that the values of ash, fats and vitamin C were not changed regardless the storage period of the analyzed raspberry and peach jams. The period of storage increased the values of total dry matter from 44.97% to 45.86%, soluble solids from 40.17 °Brix to 41.5 °Brix and total acids from 1.47% to 1.49% in raspberry jam. In peach jam these results changed from 42% to 44.1%, from 41.92 °Brix to 42.9°Brix and from 0.92% to 0.97% respectively. Microbiological examinations indicate that jams are microbiologically proper according to standards. From the overall results it can be concluded that the storage period has effect on the prepared raspberry and peach jams, but their quality remains good and has maximum consumer acceptance. 2.2. DIABETIC FRIENDLY LOW-CALORIE JAM New health concerns associated with high sugar intake include excessive calorie consumption and decreased diet quality (Weaver & Finke, 2003). The growing concern with health and the higher incidence of obesity, metabolic syndrome and diabetes has resulted in an increase in interest for foods with reduced lipids and sugar (Ogden et al., 2006; Dabelea et al., 2007). With increased consumer interest in reducing sugar intake, food products made with sweeteners rather than sugar become more popular (Pinheiro et al., 2005). Determining the best sweetener for a product requires several sensory tests. These sweeteners, in addition to being safe, meeting current law, must be compatible with the food and present the greatest similarity to the characteristic flavour of the sucrose-based product (Fernandes et al., 2001). Furthermore, it is desirable that the sweetener have a low calorie density and commercial viability (Malik et al., 2002). According to Lawless and Heymann (1999), it is widely believed that the consumer acceptability of different intensive sweeteners depends on the similarity of their time profile
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to that of sucrose. According to Cardello et al. (1999), the replacement of sucrose by alternative sweeteners can produce changes in the perception of bitter and sweet tastes. Sucralose is the only commercial sweetener derived from sucrose and is an intense sweetener made by selective substitution of the hydroxyl groups of sucrose with chlorine (Binns, 2003). According to Ketelsen et al. (1993) and Wiet & Beyts (1992), sucralose has a taste profile very close to that of sucrose, presenting very low level of bitterness and sourness. As sucralose, this is already known to have a sensory profile similar to that of sucrose, high intensity sweeteners, such as thaumatin, neotame and stevia, are being developed or improved to achieve greater similarity with sucrose (Cardoso & Bolini, 2007; Moraes & Bolini, 2010). According to Shendurce et al. (2010), the synergistic combination of sweeteners can reduce cost and improve taste and stability. Hyvonen and Torma (1983) studied the preparation of acceptable low sugar jams and replacement of sucrose by other sweeteners in jam. Strawberry jam was sweetened with sucrose, fructose, high fructose syrup, xylitol, sorbitol, lactose, saccharin, cyclamate, or with combinations of these. It was technologically possible to prepare jams with lower amounts of sucrose than currently used and still attain an acceptable product. In addition, sucrose can be replaced in strawberry jam by other sweeteners or by combinations of sweeteners. The attainment of a suitable texture may be more difficult in xylitol and sorbitol jams than in jams with other sweeteners. The use of maltodextrin as bulking agent in jam is limited by the abnormal appearance and taste it gives to the product. Keeping quality of the low sugar strawberry jams were tested during 10 months storage at room and refrigerator temperature (5°C) according to physical colour and texture measurements, and by sensory analysis. Lopez et al. (1990) described manufacture of a new low-energy form of jam roll; one of the most frequently consumed confectionery products in Chile, in which sugars are totally replaced by sweeteners. Moisture, ash, ether extract, protein, fibre, nitrogen-free extracts and total carbohydrates in the product were compared with original product. The product was well accepted by a taste panel of obese subjects. Bakr (1997) studied preparation of acceptable low energy fibre enriched and diabetic jams, cakes and biscuits using different formulae of sucrose substitute. The nutritional and storage qualities and the potential effect of most acceptable formulae from each food group on the blood glucose level of lean and obese diabetes mellitus patients was evaluated. It was technologically possible to prepare acceptable highly nutritional diabetic and low energy apricot, guava and strawberry jams and jellies using combinations of sweeteners including xylitol (xylitol-sorbitol-aspartame and xylitol-fructose). The attainment of a suitable texture was difficult in xylitol and sorbitol jams; therefore 0.2g of CaCl2.H2O was added. Storage of 33
these jams at 4°C improved their keeping quality, where the microbial load was <20 cells/g and the products were free from moulds and yeasts. Viberg et al. (1997) manufactured Blackcurrant jam with the aim of producing a jam with low sugar content, and without any additives. Four temperatures were investigated, namely 60°C, 76°C, 92°C and 97°C and processing time varied between 1 -20 min. At all combinations investigated more than 60% of the original amount of ascorbic acid was retained after manufacturing and packaging. Barwal (1999) developed low calorie (dietetic) mixed fruit jam, apple jelly and apricot squash without compromising sensory qualities, using non-nutritive sweeteners and food additives at optimum fruit constituents. The physicochemical and sensory observations were recorded at different intervals during storage period of 90 days at ambient conditions. The results indicated that the dietetic products sweetened with cyclamate were better than saccharin and were comparable with standard products. The development efforts successfully reduced caloric value in jam, jelly and squash. Anjum et al. (2000) prepared dried apricot jam by incorporating a suitable combination of sorbitol, cyclamate and aspartame instead of sucrose and glucose syrup on the equivalent solid basis. The treatments were analysed of physicochemical and sensory evaluation fortnightly for two months. Significant results were obtained for TSS, pH, acidity and reducing sugars with regard to treatments and storage periods. All the sensory characteristics affected significantly due to the differences in sweetener combinations while the effect of storage period was found to be non-significant. There was no effect of treatment and storage period on ash content of apricot jam. The TSS increased gradually in all treatments during storage periods. Poiana et al. (2011) studied the effect of thermal processing and storage period on the antioxidant properties and colour quality of strawberry, sweet and sour cherry low-sugar jam. It was observed that thermal processing of fruits led to statistical significant alterations for all monitored parameters. Additional alternations of measured parameters occur during storage. Jams storage for a period of three months at 20°C led to a decrease in vitamin C content of 22 to 33% from the value recorded one day after processing and a loss of anthocyanins content, ranging from 22% in sour cherry jam to 33% in strawberry jam related to the value recorded one day after processing. There was an increase in polymeric colour in the range of 39 to 63% from the value recorded one day after processing while for the colour density there were no statistically significant alterations.
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Correa et al. (2011) studied the development of zero sugar guava jam, its physical-chemical characterization and sensory evaluation, besides phenolic compounds quantification in guava fruit and guava jams. Two guava jam formulations were prepared: Standard Formulation (SF), with sucrose, and Zero Sugar Formulation (ZSF) in which sucrose was replaced by a mix of sweeteners. The following physical-chemical analyses were performed: pH, soluble solids (°Brix), reducing sugars, water activity, acidity, ash and moisture. The soluble solids content found for SF was 65.03 °Brix while the value found for ZSF was 50.75°Brix, which is expected for diet and light jams. The replacement of sucrose with sweetener in ZSF allowed the reduction of approximately 40% in the reducing sugar content, very significant result. The values of total acidity and water activity were within recommended values to prevent syneresis and growth of pathogens. Sensory analysis was performed with 50 untrained panellists using a paired test, to identify the preferred formulation, in addition to a 9-point hedonic scale test, to evaluate attributes of colour, aroma, flavour and texture in guava jam formulations. Results for the paired test revealed no significant difference between the acceptance of SF jam and ZSF jam by the panellists. They also performed the quantification of phenolic compounds in guava fruit and guava jam samples, varying the amount and concentration of ethanol used as extractor solvent. The levels of polyphenols found in all samples reveal potential antioxidant activity of guava fruit and guava jam. Youssef and Mousa (2012) investigated the nutritional status of low-calorie Baladi rose petals jam including the pH, total soluble solids, gross chemical composition, caloric value and mineral composition. Three types of jam, namely: fresh Baladi rose petals jam with 40% sugar, fresh Baladi rose petals with 40% sorbitol and dried Baladi rose petals with 40% sorbitol were processed. Sensory evaluation proved that both fresh Baladi rose petals jam with 40% sugar or 40% sorbitol recorded best scores. Jam constituents ranged between 11.86 to 22.42% crude protein, 2.71 to 15.50% crude fat, 0.89 to 1.53% ash, 6.39 to 7.42% crude fibre, 66.36 to 68.18% carbohydrates, 20.92 to 24.30% moisture and 381.65 to 452.38 kcal/100g respectively. The Baladi rose petals with 40% sugar or 40% sorbitol could be recommended for the diet regimen of diabetic persons. Souza et al. (2013) studied the equivalent amount of different sweeteners, necessary to promote the same degree of ideal sweetness by sucrose in mixed fruit (marolo, sweet passion fruit and soursop) jam and to characterize the time-intensity profile and consumer acceptance. With respect to the mixed fruit jam containing 40% (w/w) of sucrose, sucralose presented the highest sweetening power, being 1033.59 times sweeter than sucrose, followed by sucralose/acesulfame-K/neotame 5:3:0.1 (982.80), sucralose/steviol glycoside 2:1 (862.67), sucralose/acesulfame-K 3:1 (847.45) and sucralose/thaumatin 1:0.6 (284.29). 35
In relation to sensory acceptance, a significant difference between the low-sugar jam and the traditional jam was not observed. 2.3. SENSORY EVALUATION Sensory evaluation is the process of evaluating any product using human senses. Many works are available based on the evaluation of products by sensory methods. During sensory analysis, discrimination and description may be used as methods of analysis (Dehlholm, 2012). Normally 9 – point hedonic scale is widely used for sensory analysis. The method of analysis differs with each product. As for all consumables, sensory characteristics are important for the jam too. These characteristics are the ones that the consumers grade every day and based on which they decide whether to buy a particular product or not. In this type of analysis, sensory attributes of the product are determined such as: colour, scent, taste and consistency. Shakir et al. (2009) carried out a comparative study on mixed fruit jam of apple and pear pulp. All jam samples were stored in sterilized glass jars at ambient temperature and evaluated for total fungal count and sensorically observed for colour, taste, texture and overall acceptability for interval of 15 days during three months storage period. Result showed a decrease in colour score. Taste and texture of jam also showed a decrease in score. Results regarding to overall acceptability also decreased gradually. Oyeyinka et al. (2009) studied the sensory analysis of jam prepared from osmo-dehydrated cashew apple. Pre-frozen whole cashew apples were soaked in varying osmotic solution concentration at different soaking times before conversion into jam products. Jam made with sugar solution of 60°Brix without osmotic treatment was used as a reference sample and other samples were compared with it. Generally, jam made from 50°Brix for 3 and 4 h were most preferred by the panellist. The spreadability of all the jam samples was poorly scored by the panellists. Muhammad et al. (2009) investigated the effect of non-calorie sweeteners (aspartame, cyclamate and saccharin) on the sensory characteristics of diet apple jam. All the samples were stored in sterilized glass jars and were subjected to sensory evaluation fortnightly for three months of storage. Statistical analysis showed that storage intervals and treatments had a significant effect on sensory quality of diet apple jam. Ajenifujah and Aina (2011) investigated the possibility of producing jam from black-plum and to evaluate the consumer acceptability of the product. Sensory evaluation by untrained panellists indicated consumer acceptability. Statistical evaluation between black-plum jam 36
and commercial black currant jam on a nine point hedonic scale showed a preference for the commercial jam, particularly in terms of colour. The differences in flavour and spreadability were not significant, while the differences in colour, taste and overall acceptability were significant. Patel and Naik (2013) prepared pineapple and banana blended jam. In respect to sensory characters, banana:pineapple 25:75 proportion was found best having higher score pertaining to colour, taste and overall acceptability except texture and flavour which was found best in proportion of 50:50 and 0:100. All sensory characters were found decreasing during storage. The lowest acceptability was found in sole banana jam in respect to all sensory parameters. Considering these parameters proportion of 25:75 and 50:50 were found best than rest of the proportions of jam during storage. Jayabalan and Karthikeyan (2013) done work on the sensory quality of jam produced by aloe vera. Response surface methodology (RSM) was used to optimize the ingredients for preparing aloe vera jam with high acceptance. Sensory analysis for colour, taste, aroma and texture in the jam produced at the optimized ingredients composition were performed. The optimum condition for the best sensory score is aloe vera juice 990ml, sugar 1022 g/kg, pectin 50.3 g/kg and citric acid 28.2ml. Jam produced under the optimum conditions for sensory score was again subjected to evaluation of sensory values and the results were compared with the RSM predictions. Eke-Ejiofor and Owuno (2013) evaluated the sensory properties of jackfruit jam. Result from sensory evaluation using a five point hedonic scale to rate the col our, aroma, taste, after taste, texture and general acceptability by untrained panellists indicated general acceptance of jackfruit jam. Results from sensory analysis showed that colour ranged from 3.7 to 4.4, aroma from 3.7 to 4.4, taste from 3.8 to 4.6, after taste from 3.4 to 4.3 and general acceptability from 3.9 to 4.5, with jackfruit lower than the control in all cases, while texture ranged from 3.7 to 4.3 and spreadability from 3.5 to 4.5 with jackfruit having a higher value in both cases. There was a significant difference in colour, aroma, taste and general acceptability with control rated higher. While texture and spreadability showed no significant difference. Assessors however scored jackfruit jam high for flavour and spreadability. Ihediohanma et al. (2014) evaluated the sensory quality of jam produced from Jackfruits. The prepared jam after cooling was served to panellist to compare sensory acceptability of the jackfruit jam along with pineapple and orange jam. Sensory evaluation revealed significant difference in colour and aroma of the samples while there was no significant difference in the texture and sweetness of samples tested.
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Muresan et al. (2014) investigated the quality of banana-ginger jam by physic-chemical analyses and general consumer’s acceptance. The analyses were conducted on three prototypes of jam, first banana jam without addition of ginger, then banana jam with 2% ginger and banana jam with 4% ginger. By sensory analysis acceptability, preference and product differentiation was determined. The study indicated that banana jam with 2% ginger was the most preferred one by consumers. Viana et al. (2014) evaluated the physicochemical and sensory properties of mixed jam elaborated with banana and araçá-boi. Four banana extract (BE) and araçá-boi (AB) jams were prepared using the following proportions. F1 (70% BE:30% AB), F2 (60% BE:40% AB), F3 (40% BE:60% AB) and F4 (30% BE:70% AB). The jams were analyzed for physicochemical and sensory properties. The sensory acceptance test was performed by 50 panelists who were asked to indicate how much they liked/disliked the jams based on the following attributes: colour, aroma, flavour and texture. The global analysis of the internal preference mapping verified that formulations F1 and F2 were preferred for flavour and had good acceptance levels for the other evaluated attributes, which indicated that the consumers favoured jams with lower concentrations of AB and higher concentrations of BE. The formulation F1 was considered the most accepted for all attributes evaluated. Aleksander et al. (2015) conducted sensory analysis of raspberry jam with different sweeteners. The aim was to determine the sensory differences between the raspberry jam with sucrose and jams prepared with other sweeteners (fructose, sorbitol and Agave-syrup). The traditional hedonic test of acceptance on a scale of 9 points was undertaken on a group of 13 untrained examinees. The results obtained have shown that only 7 to 15% of the examinees gave negative or neutral grades for all the jams. Jam sweetened with sorbitol had the best hedonic grades in comparison with the rest of the jams, while the lowest grade was given to the jam sweetened with sucrose. James et al. (2016) prepared mixed fruit jam from blends of pineapple, tomato and pawpaw at different ratios, while commercial strawberry jam served as control. Jams made from different fruit ratios and the control was examined for their proximate composition, mineral contents as well as sensory attributes. In sensory attributes, the control and the test samples showed no significant difference in texture and flavour. In taste, the test samples were found to be significantly high than the control. In appearance and general acceptability, the control and the test samples compared favourably. Hence, samples with 17% pineapple, 14% tomato and 13% pawpaw and 16% pineapple, 16% tomato and 12% pawpaw compared favourably with the control in chemical and sensory attributes.
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The works related to jam disclose that different types of fruits can be used for the preparation of jam as individual fruit or in combination with others. Some works were conducted in the utilization of overripe fruits for jam preparation, but comparatively less. Most of the researchers used fresh fruits for their works. Recently, studies related to diabetic friendly, sugar free and low-calorie jams were done due to the concern of health problems. Development of diabetic friendly low-calorie jams from different fruits will be the next challenge for most of the scientists.
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3. MATERIALS AND METHODS
The present study was conducted at Pineapple Research Station, Vazhakulam. Overripe fruits of pineapple and banana and other ingredients required for this study were procured from Vazhakulam and Ernakulam wholesale market. Fruits were picked at much ripened stage without any pathological damage.
Fig 3.1. Overripe fruits used for Jam preparation: Vazhakulam Pineapple, Palayankodan, Njalipoovan and Karpooravalli
3.1. Materials 3.1.1. Materials Required: Vazhakulam pineapple, Banana varieties (Ba1: Palayankodan, Ba2: NjalipoovanandBa3: Karpooravalli), Sugar, Citric acid, Pectin, Malto-dextrin, Sorbitol (70% solution, Viveka) and Sucralose (Sugar Free Natura, Zydus Wellness). 3.1.2. Chemicals Required: 0.1 N Sodium hydroxide, Phenolphthalein indicator, 4% Oxalic acid, DCPIP (2,6-dichlorophenol indophenols) dye solution, Standard ascorbic acid, Fehling’s solution (A), Fehling’s solution (B), Methylene blue indicator, 45% Neutral Lead Acetate and 22% Potassium Oxalate.
3.2. Methods 3.2.1. Preparation of Fruits for Jam Making Pineapple fruits were peeled very carefully with clean sharp knife, cut into four halves and central fibrous portion was removed. Then it was pulped in a blender. Clear fruit pulp was obtained by squeezing the fruit pulp through muslin cloth. Banana fruits were peeled by hand and cut into small pieces after removing central portion.
41
Pulp was prepared by
homogenizing the fruit pieces in blender. Then these fruit pulps were mixed in different proportion for jam making. 3.2.2. Jam Preparation The jams were prepared as per the procedure adopted in Pineapple Research Station, Vazhakulam. Jams were prepared in different proportions by varying the amount of fruit pulp used. 3.2.2.1. Method of Preparation Mix all ingredients together and keep some time for complete dissolving of sugar. Cook it on a low fire and stir continuously with a ladle. Determine the end point using refractometer method, drop test or sheet test. When the jam is done, remove from fire and pour in to sterilized bottle. When it cools, close the mouth of the bottle. In the preparation of diabetic friendly jam sucralose and sorbitol were used as sweeteners instead of sugar. Malto-dextrin was also used for getting the bulkiness of jam. 3.2.2.2. Ingredients (for 700g of jam) The ingredients were mixed as per the quantities given in the following Table 3.1. Table 3.1 Ingredients and amount used for normal and diabetic friendly jam Normal Jam
Diabetic Friendly Jam Pulp
500 g
Pulp
500 g
Malto-dextrin
300 g
Sugar
500 g
Sorbitol
100 g
Citric acid
2.5 g
Citric acid
2.5 g
Pectin powder
2.5 g
Pectin powder
2.5 g
Sucralose
25 g
3.2.2.3. Treatment Details Altogether 13 combinations of jam using pineapple and banana in different proportions were prepared for this work.The treatment details of both normal and diabetic friendly jams were given in Table 3.2 and 3.3.
42
Table 3.2 Proportion of pulp used for jam preparation Blending Ratio (Pineapple:Banana)
Sample
Pineapple
Ba1
Ba2
Ba3
J1
100
0
0
0
J2
75
25
0
0
J3
50
50
0
0
J4
25
75
0
0
J5
0
100
0
0
J6
75
0
25
0
J7
50
0
50
0
J8
25
0
75
0
J9
0
0
100
0
J10
75
0
0
25
J11
50
0
0
50
J12
25
0
0
75
J13
0
0
0
100
From these 13 samples, best 3 combinations from each category were selected based on physicochemical as well as sensory analysis. Diabetic friendly jam was prepared using these 3 combinations and quality parameters like nutritional value, physicochemical attributes and consumer acceptance by organoleptic methods were evaluated for these samples. Table 3.3 Treatment details of Diabetic friendly Jam Sample
Pineapple
Ba1
Ba2
Ba3
D1 (J3)
50
50
0
0
D2 (J6)
75
0
25
0
D3 (J10)
75
0
0
25
In the analysis, 2 replications were done for analysis. 3.2.3. Physicochemical analysis of samples Analytical procedures and methods were followed for the determination of Total Soluble Solids (TSS), acidity, ascorbic acid, reducing sugar, non-reducing sugar, total sugar, pH, ash content and moisture content of the prepared products as well as fruits (AOAC, 1998). 43
Determination of acidity Acids are important constituents in fruits together with sugar. They determine quality and taste of the fruit. Maturity of many fruitsfor their harvest is also judged from their level of acids along with sugar or soluble solids. In some fruit, one or more acid may present in relatively high amount than the other acids and accordingly, these are referred to as predominant acids respective to these fruits. For example, citric acid is the predominant acid in fruits like citruses, strawberry, lemon, etc. while malic acid is predominant in apple, cherry, plum, etc. Tartaric and malic acids are present in grapes and citric and malic acids in passion fruit. Principle The total acidity of a fruit could be determined by titrating a known amount of aqueous extract of it against an alkali solution of known normality. It is expressed as equivalence of any organic acid, eg: citric acid and malic acid. Reagents Sodium hydroxide solution: 50 ml 0.1N NaOH by dissolving 0.2g of NaOH in 50 ml water. Phenolphthalein (C20H14O4) indicator, approx. 0.5% in 80% ethanol. Procedure Take 5 g jam sample, add 50 ml distilled water and boil for 1 hour replacing the water lost by evaporation. Cool, transfer to a volumetric flask and make up to 100 ml. Filter, if necessary. Take 5 ml of the sample prepared as above and add 10 ml recently boiled distilled water. Titrate with 0.1N NaOH using a few drops of phenolphthalein solution as indicator. Note the titre value. Calculate the results as per cent anhydrous citric acid or other acids. Calculation % TA = Where,
T = Titre value V1 = Volume Made
T × N × V × EW × V ×W×
N = Normality of NaOH (0.1N)
V2 = Volume of sample taken for estimation
EW = Equivalent weight of citric acid (70.0 g) W = Weight or volume of sample taken 44
Determination of ascorbic acid or vitamin C Vitamin C or ascorbic acid is an enediol isomer of 2-keto-gluconolactone with a configuration similar to that of L-glucose. Oxidation of ascorbic acid gives rise to dehydro ascorbic acid and both forms are physiologically active. Principle Titrimetric estimation of vitamin C is conventionally done using 2,6-dichlorophenol indophenols dye solution. This dye is blue in alkaline solution and red in acidic solution. Ascorbic acid reduces the dye to a colourless form. Reaction is quantitative and specific for ascorbic acid at pH 1.0 – 3.5. Reagents 4% oxalic acid: 40 g of oxalic acid is dissolved in 1000 ml of distilled water. DCPIP dye solution: Dissolve 0.250 g of sodium salt of 2,6-dichlorophenolindophenols in about 500 ml of water containing 0.210 g of NaHCO 3 and dilute to 1 litre of water. Store the solution in refrigerator. Standard ascorbic acid (C6H8O6): 0.01% ascorbic acid is dissolved in oxalic acid. Procedure Take 5 g of sample and make up to 100 ml with 4% oxalic acid. Take 5 ml sample from 100 ml and add 10 ml 4% oxalic acid and titrateagainst the dye 2,6-dichlorophenol indophenols. The end point is determined by the appearance of pink colour which should persist for at least 15 seconds. Calculation
Where,
Ascorbic acidmg⁄
g=
.5 × V × × V ×5×W
V1 = Titre value of standard ascorbic acid solution V2 = Titre value of sample
W = Weight of sample
Determination of reducing and total sugar (Lane – Eynon Method) The Lane and Eynon method has been found to be more simple and rapid method. This method has been recommended by AOAC for the determination of reducing and total sugars in fresh and processed fruits. 45
Principle Invert sugar reduces the copper in Fehling’s solution to insoluble cuprous oxide (red). The sugar content in the sample is estimated by determining the volume of the unknown sugar solution required to completely reduce a measured volume of Fehling’s solution by titration using methylene blue as indicator. Reagents Fehling’s solution (A): Dissolve 69.28 g copper sulphate (CuSO 4. 5H2O) in water, dilute to 1000 ml and, if necessary, filter through No. 4 Whatman paper. Fehling’s solution (B): Dissolve 346 g of Rochelle salt (potassium sodium tartrate, KNaC4H4O6. 4H2O) and 100 g NaOH in water and make up to 1000 ml. Methylene blue indicator: Dissolve 1 g of methylene blue in 100 ml of water. 45% Neutral Lead Acetate solution: Dissolve 225 g of neutral lead acetate in water and dilute to 500 ml. 22% Potassium Oxalate solution: Dissolve 110 g of potassium oxalate (K 2C2O4. H2O) in water and dilute to 500 ml. Procedure Place 50 g of the blended jam in an 800 ml beaker and add 400 ml of water. To prevent inversion of sugars during boiling extraction, neutralize the solution to pH 7.58 with 0.1N NaOH, using a pH meter. Boil gently for 1 hour, with occasional stirring. Add boiling water to maintain the original level. Cool, and transfer to a 500 ml volumetric flask. Make up to volume and filter through No. 4 Whatman paper. Pipette a 100 ml aliquot into a 500 ml volumetric flask. Add 2 ml of neutral lead acetate solution and about 200 ml of water. Let stand for 10 minutes, then precipitate the excess Pb++ with 2 ml potassium oxalate. Make up to volume, shake well and filter through No. 4 Whatman paper. Reducing sugars Pipette 50 ml of the clarified solution into a 100 or 250 ml volumetric flask. Make up to volume and titrate by the “Standard Method”.
46
Total sugars Pipette 50 ml of the clarified solution into a 250 ml Erlenmeyer flask. Add 5 g of citric acid and 50 ml of water. Boil gently for 10 minutes to invert sucrose, then cool. Transfer to a 250 ml volumetric flask and neutralize using 1 N NaOH. Make up to volume and titrate by the “Standard Method”. Standard Method of Titration Pipette 10 ml of mixed Fehling’s Solution (A and B) into duplicate 250 ml Erlenmeyer flask. Fill the 50 ml burette with the solution to be titrated. Run into the flask almost the whole volume required to reduce the Fehling’s solution, so that not less than 0.5 ml or more than 1.0 ml is required later to complete the titration. Mix the contents of the flask. Heat to boiling and boil moderately for 2 minutes, then add 2 drops of the methylene blue solution, taking care not to allow it to touch the side of the flask. Complete the titration within 1 minute by adding 2 to 3 drops of sugar solution at 5 to 10 second intervals, until the indicator is completely decolourized. At the end point the boiling liquid assumes the brick-red colour of precipitated cuprous oxide, which it had before the indicator was added. Calculations
Where,
% Reducing or Total Sugar =
F × T ×
×D
F = Factor for 10 ml of Fehling’s solution (Appendix-1) D = Dilution
T = Titre Value
Determination of non-reducing sugar The non-reducing sugar present in the sample can be determined from the values of total and reducing sugar as follows. % Non-reducing sugar = % (TS - RS)
Where,
TS = % Total Sugar
RS = % Reducing Sugar
47
Determination of moisture content Water is one of the major constituent in a food. It is held to other constituents by physical and chemical forces of diverse nature and strength. Moisture content is defined as the loss of weight when the material is heated under the conditions of the experiment. Principle Standard method for moisture determination by oven drying stipulate drying at a certain temperature either for a specified time or until constant weight is achieved. The sample is dried at 100±5°C for 2 to 4 hours in a forced draft air oven. The loss in weight is reported as moisture. Procedure Weigh accurately 5 g of sample into moisture dish. Keep it in a hot air oven maintained at 100±5°C for 3-4 hours. After drying is complete, remove samples from the oven and place in desiccator. Cool to room temperature and weigh accurately. Continue heating and cooling till two consecutive reading taken at half an hour interval show no change. A duplicate is also conducted. Calculation
Where,
% MoistureContent =
A = Sample weight in g
B−C × A
B = Weight of dish + Sample prior to drying C = Weight of dish + Sample after drying
Determination of ash content The ash content of food stuff is the inorganic residue remaining after the food is ignited until it is carbon free. The ash figure can be regarded as a general measure of quantity and often is a useful indication of identity. The total ash content of the dried samples is determined using muffle furnace.
48
Procedure Weigh accurately 3 to 5 g of well mixed sample in the crucible. The crucible is placed on a clay triangle and heated at a low flame until the material is charred. The charred material is kept inside the previously set muffle furnace and heated at 600±20°C for 3-4 hours until light gray or white ash is obtained. The crucible is cooled in a desiccator and weighed. The crucible is again heated for further 30 minutes, cooled & weighed. Calculation
% Ash Content = Where,
W = Weight of sample in gram
W
g × W g
W1 = Weight of ash in gram
Determination of total soluble solids (TSS) Total soluble solids (TSS) are solids that are dissolved within a substance. A common total soluble solid is sugar. The technique of measuring the concentration of TSS is called refractometry. It can be determined using hand as well as digital refractometer. TSS or °Brix of fruits and jams were determined with a Digital Refractometer (HI 96801, 090°Brix). First of all calibrate the refractometer with distilled water to 0°Brix. Then place the sample on the equipment and record the reading. The readings were taken at 20°C (Appendix-2).
Determination of pH pH is the measure of acidity or basicity of an aqueous solution. The solution with a pH less than 7 are said to be acidic and solution with a pH greater than 7 are basic or alkaline. Pure water has a pH very close to 7. pH is defined as the decimal logarithm of the reciprocal of hydrogen ion (H+) activity in the solution. A typical pH meter (Metler Toledo) consists of special measuring probe (a glass electrode) connected to an electronic meter that measures and displays the reading. The probe is a key part of a pH meter; it is a rod like structure. At the bottom of the probe there is a bulb, and the bulb is the sensitive part of the probe that contains the sensor.
49
First calibrate the pH meter using buffer solutions of pH value 7.0 and 4.0. Then dip the probe in a sample solution, whose pH is to be measured, press the call button of the pH meter and take reading. 3.2.4 Sensory Evaluation Nine untrained panellists took part in sensory analysis of jam samples. The sensory evaluation for colour, flavour, texture, taste, sweetness and overall acceptability were done in order to determine consumer acceptability. These parameters were evaluated based on 9 point hedonic scale (Amerine et. al., 1965). The scale ranged from 1 – dislike extremely to 9 – like extremely.
50
SENSORY EVALUATION OF JAM Date: ....../....../............... Name: ............................................................................................................. Age: ................................................................................................................
Hedonic Scale
1
2
3
4
5
6
7
8
9
Sensory Attributes Samples
Colour
Flavour
Texture
Taste
Sweetness
Overall Acceptability
J1 J2 J3 J4 J5 J6 J7 J8 J9 J10 J11 J12 J13
Signature Fig. 3.2. Score Sheet Used for Sensory Evaluation of Jam
51
3.3. Instruments used for the Analysis
Fig 3.3. pH Meter
Fig 3.4. Desiccator
Fig 3.5. Electronic Weighing Balance
Fig 3.6. Hot Air Oven
Fig 3.7. Water Bath
Fig 3.8. Hand Refractometer
Fig 3.10. Muffle Furnace
Fig 3.11. Burettes
Fig 3.9. Digital Refractometer
Fig 3.12. Blender
3.4. Ingredients and Products
Fig 3.13. Ingredients for Normal Jam
Fig 3.14. Normal Jams
Fig3.15. Ingredients for Diabetic Friendly Jam
Fig 3.16. Diabetic Friendly Jam
4. RESULTS AND DISCUSSION
The present study was conducted at Pineapple Research Station, Vazhakulam. Preparation of samples and the quality analysis of prepared samples as well as fruits were carried out as per the procedure described in Chapter 3. The results are discussed in this chapter.
4.1. Physicochemical Analysis Physicochemical analyses were conducted as per the methods described in Chapter 3. Analyses of overripe fruits of pineapple and banana varieties, normal jam samples as well as diabetic friendly jams were conducted. The details are given below.
4.1.1. Fruits Overripe fruits of pineapple and 3 varieties of banana vi z. Palayankodan, Njalipoovan and Karpooravalli were analyzed. Physiochemical parameters like pH, titratable acidity, ascorbic acid, TSS, moisture, ash and total, reducing and non-reducing sugars were analyzed. Details of analysis were given below. pH and Titratable Acidity The mean values of pH and titratable acidity of fruits are given in Table 4.1. pH and titratable acidity are inversely proportional to each other. Pineapple has the highest titratable acidity of 0.16% citric acid with a pH value of 3.46. All 3 varieties of banana have same titratable acidity with slight variation in pH values ranging from 4.52 to 4.77. Titratable acidity reflects organic acid content of fruits. Citric and malic acids are the two major organic acids in pineapple fruit, with a ratio of about 2-3 to 1 (Chan et al., 1973). Lower pH of could be attributed to the presence of organic acids, such as malic acid, in ripe banana fruits (Wyman and Palmer, 1964). Table 4.1. pH and Titratable Acidity of Fruits Fruit
pH (27°C)
Acidity (% CA)
Pineapple
3.46
0.16
Ba1
4.77
0.064
Ba2
4.58
0.064
Ba3
4.52
0.064
NB: “Ba” in the table refers to different banana varieties used in the jam preparation
55
Ascorbic Acid Mean values of ascorbic acid content of pineapple and banana are given in Fig 4.1. Ascorbic acid or vitamin C content was high in pineapple (30.3 mg/100g) followed by Karpooravalli (18.18 mg/100g). It was observed that both Palayankodan and Njalipoovan varieties have same vitamin C content. 0.6 g of acid was present in 100 g edible portion of pineapple fruit which contained 63 mg of vitamin C. Ascorbic acid content of pineapple is high according to Ding and Syazwani (2016).
Fig. 4.1. Ascorbic acid content of fruits.
Total Soluble Solids TSS content was determined by using Digital refractometer and is referred to as the °Brix. At 20°C, the °Brix is usually considered equivalent to the percentage of sucrose (sugar) in the solution (60° Brix is equivalent to a sugar content of 60%). This measurement was made at 20°C to get an accurate value. The mean values are given in Table 4.2. It was found that banana have more TSS content than pineapple. In banana, Karpooravalli contain high TSS followed by Palayankodan and Njalipoovan. Vazhakulam pineapple is sweet with 14 to 16° Brix and its acidity is 0.50 to 0.70% (Joy, 2013). TSS value of pineapple was in accordance with the observations of Ding and Syazwani (2016).
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Table 4.2. TSS of Fruits Fruit
TSS (°Brix)
Pineapple
16.8
Ba1
24
Ba2
21.3
Ba3
26.4
NB: “Ba” in the table refers to different banana varieties used in the jam preparation
Fig. 4.2. TSS of Fruits
Moisture Moisture content was determined by using oven dry method and expressed in percentage. The mean values are given in Table 4.3. It was observed that pineapple contain more moisture compared to banana varieties. The values ranged from 71.82% (Karpooravalli) to 83.95% (Pineapple). Njalipoovan variety had more moisture content compared to other two banana varieties. The observations were almost in accordance with the findings of Hettiaratchi (2011).
57
Table 4.3. Moisture Content of Fruits Fruit
Moisture (%)
Pineapple
83.95
Ba1
72.04
Ba2
75.67
Ba3
71.82
NB: “Ba” in the table refers to different banana varieties used in the jam preparation
Ash Content Mean values of ash content are given in Fig 4.3. The ash values can be said to be concomitant with the mineral element composition. Banana possesses high ash content than pineapple because of high mineral content of banana. Among three banana varieties, Njalipoovan possess high ash content compared other two varieties. The observations were almost in accordance with the findings of Hettiaratchi (2011).
Fig. 4.3. Ash Content of Fruits
Total, Reducing & Non-Reducing Sugar Mean values of total, reducing and non-reducing sugars of pineapple and banana varieties were given in Table 4.4. The total sugar was higher in Karpooravalli (13.12%), and lower in pineapple (12.65%). While in case of reducing sugar, it was highest in pineapple (8.13%) and lowest in Palayankodan (7.52%). Non-reducing sugar content was high in Njalipoovan (5.39%) and low in pineapple (4.52%). Chan et al., (1973) also observed almost similar values in pineapple.
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Table 4.4. Total, Reducing and Non-reducing Sugar Content of Fruits Fruit
Total Sugar (%)
Reducing Sugar (%)
Non-reducing Sugar (%)
Pineapple
12.65
8.13
4.52
Ba1
12.85
7.52
5.33
Ba2
13.02
7.63
5.39
Ba3
13.12
7.94
5.18
NB: “Ba” in the table refers to different banana varieties used in the jam preparation
Fig. 4.4. Total Sugar (TS), Reducing Sugar (RS) and Non-reducing Sugar (NRS) Content of Fruits
4.1.2. Jam 13 combinations of jam samples were prepared by varying the proportion of pineapple and banana pulp. Physicochemical parameters viz. pH, titratable acidity, TSS, moisture, ash and total, reducing and non-reducing sugar of these samples were analysed. Results obtained from these analyses are given below. pH The pH of jam is an important factor to obtain optimum gel condition. Table 4.5 reveals the pH of different jam samples prepared using combinations of pineapple and bana na. The values ranged from 3.73 to 4.61. While considering same proportion of samples, not much change was observed. As the proportion of banana pulp increased, the pH value also
59
increased. One of the critical control points in the jam manufacturing is the pH of the fruit pulp in balancing the sugar and pectin in order to facilitate gel formation (Belitz and Grosch, 1999; Dauthy, 1995). Table 4.5. pH of Jam Samples Sample
pH (27°C)
Sample
pH (27°C)
J1
3.73
J8
4.12
J2
4.07
J9
4.52
J3
4.28
J10
3.94
J4
4.40
J11
3.96
J5
4.61
J12
4.07
J6
3.85
J13
4.25
J7
4.08
Titratable Acidity Titratable acidity (% citric acid) of jam was found almost similar in all samples. The mean values are given in Table 4.6. It was maximum in J1 (0.63%) and minimum in J3 and J11 (0.49%). All other samples had same titratable acidity. From the given table it is clear that the titratable acidity of all the samples were almost similar and in accordance with the FPO specification. These findings were almost in accordance with results obtained by Patel and Naik (2013). According to FPO specification (1955), the acidity of jam should be 0.5 to 0.7%. Table 4.6. Titratable Acidity of Jam Samples Sample
Acidity (% CA)
Sample
Acidity (% CA)
J1
0.63
J8
0.56
J2
0.56
J9
0.56
J3
0.49
J10
0.56
J4
0.56
J11
0.49
J5
0.56
J12
0.56
J6
0.56
J13
0.56
J7
0.56
Ascorbic Acid An overall ascorbic acid (mg/100g) of jam (Table 4.7) was found highest in J1 and J10 (24.24 mg/100g) and lowest in J5 and J9 (12.12 mg/100g). Samples with same proportion of fruit 60
pulp gave very close values. In case of individual fruit jam, the values were almost in accordance with the values of original fruits used. This kind of observations were also recorded by Patel and Naik (2013), Sakir et al. (2008) in apple and pear mixed fruit jam and Sawant et al. (2009) in kokam-pineapple blended jam. Table 4.7. Ascorbic acid Content of Jam Samples Sample
Ascorbic acid (mg/100g)
Sample
Ascorbic acid (mg/100g)
J1
24.24
J8
15.15
J2
21.21
J9
12.12
J3
18.18
J10
24.24
J4
18.18
J11
21.21
J5
12.12
J12
18.18
J6
21.21
J13
15.15
J7
18.18
Total Soluble Solids The TSS content (Table 4.8) of prepared jam was found to be maximum in J 1 (82.4°Brix) and minimum in J4 (71.3°Brix). Higher TSS content values were obtained by Singh et al. (2009) in mixed jams of pineapple and papaya (70.5°Brix) as well as in mixed jams of papaya and orange (72.5°Brix). The TSS content values lower than 60°Brix make the gel weak and the TSS content values higher than 70°Brix may cause crystallization of sugar, an undesirable change in the texture of jam. The TSS content is also responsible for a higher or lower acceptance of the product, and jams with TSS content between 65 and 70°Brix had a good sensory acceptance according to several authors (Lago et al., 2006; Damiani et al., 2008). In case of 25:75 (pineapple:banana) proportion, two samples showed almost same TSS value, while one sample gave higher value compared to other two. In individual samples also, two were almost similar and other two samples were much differ in values. In all other proportions the values were more or less in same range.
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Table 4.8. TSS Content of Jam Samples Sample
TSS (20°C)
Sample
(°Brix)
TSS (20°C) (°Brix)
J1
82.4
J8
72.6
J2
77.4
J9
73.2
J3
76.5
J10
81.7
J4
71.3
J11
77.9
J5
76.1
J12
80.1
J6
80.3
J13
76.7
J7
74.2
Fig. 4.5. TSS of 25:75 (Pineapple:Banana) and Individual Jam samples Moisture The moisture content (Table 4.9) ranged from 9.52% (J1) to 18.50% (J4) which were comparatively less compared to values observed by Viana et al. (2012) in mixed jams of papaya (25.99% to 29.93%). It is important to note that moisture content is directly related to the conservation of product in storage, and jams with lower moisture content have a longer shelf-life. According to Eke and Owuno (2013), jackfruit jam had higher moisture content than pineapple jam and there was a significant difference in moisture between the pineapple and jackfruit jam.
62
Table 4.9. Moisture Content of Jam samples Sample
Moisture (%)
Sample
Moisture (%)
J1
9.52
J8
17.01
J2
12.95
J9
16.91
J3
13.02
J10
9.88
J4
18.50
J11
11.29
J5
13.77
J12
10.91
J6
10.27
J13
13.24
J7
15.16
Ash Ash content gives an indication of minerals present in a particular food sample and it is very important in many biochemical reactions which aid physiological functioning of major metabolic processes in the body. Mean values are given in Table 4.10. The values ranged from 0.45% to 0.69%. The lowest value was found in case of pineapple jam while highest values for Karpooravalli jam. Values of all samples were almost in same range. Lower ash content is due to increased activities of microorganism utilizing the minerals for growth (Ashaye et al., 2006). Table 4.10. Ash Content of Jam samples Sample
Ash (%)
Sample
Ash (%)
J1
0.45
J8
0.56
J2
0.51
J9
0.67
J3
0.52
J10
0.55
J4
0.57
J11
0.58
J5
0.66
J12
0.59
J6
0.53
J13
0.69
J7
0.54
Total Sugar Total sugar (invert) contents (Table 4.11) among the jams differed, but storage period did not affect its contents. The total sugars (%) of jam was found maximum in J1 (80.41%) and minimum in J4 (70.36%). The values of total sugar were almost in accordance with the values of TSS of jam samples. In case of TSS, total sugar also showed some variations in 25:75 proportion and individual fruit jam samples. The values of total sugar content of jamun, 63
apple, pineapple, mango, mix fruit and peach jams were found as 69.12, 66.84, 72.42, 72.97, 70.62, and 69.14% respectively as the study conducted by Jaiswal et al. (2015). Table 4.11. Total Sugar Content of Jam Samples Sample
Total Sugar (%)
Sample
Total Sugar (%)
J1
80.41
J8
70.61
J2
75.98
J9
71.41
J3
73.69
J10
78.82
J4
70.36
J11
75.98
J5
72.84
J12
77.61
J6
77.37
J13
74.56
J7
71.21
Fig. 4.6. TSS and Total Sugar of Pineapple:Banana (75:25 & 50:50) Jam Samples
Reducing Sugar The mean values of reducing sugar were given in Table 4.12. The value was maximum in J1 (59.86%) and minimum in J5 (52.89%). Only individual jam samples showed some differences in reducing sugar values. All other proportions of pineapple and banana (75:25, 50:50 and 25:75) gave approximately same values. The values obtained in 75:25 and 50:50 proportions were roughly in accordance with the study of Patel and Naik (2013). According to Viana et al. (2014), the values of reducing sugar ranged from 39.02 to 50.89% in banana and Araçá – Boi jam.
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Table 4.12. Reducing sugar Content of Jam Samples Sample
Reducing Sugar (%)
Sample
Reducing Sugar (%)
J1
59.86
J8
56.92
J2
57.05
J9
57.56
J3
56.42
J10
57.05
J4
54.71
J11
54.95
J5
52.89
J12
54.83
J6
57.30
J13
55.42
J7
56.29
Fig. 4.7. Reducing Sugar of Individual Jam Samples
Non-reducing Sugar The non-reducing sugar content (Table 4.13) of prepared jam were varied from 13.69 (J 8) to 22.78% (J12). Slight variations in values were observed in all combinations. These results were more or less similar to the study by Mulla (2007) in mixed fruit jam, Patel and Naik (2013) in pineapple and banana mixed jam and Sakir et al. (2008) in apple and pear mixed fruit jam.
65
Table 4.13. Non-reducing Sugar Content of Jam Samples Sample
Non-reducing Sugar (%)
Sample
Non-reducing Sugar (%)
J1
20.55
J8
13.69
J2
18.93
J9
13.85
J3
17.27
J10
21.77
J4
15.65
J11
21.03
J5
19.95
J12
22.78
J6
20.07
J13
19.14
J7
14.92
Fig. 4.8. Non-reducing Sugar of Different Proportion of Jam Samples 66
4.1.3. Diabetic Friendly Low-calorie Jam Three combinations of sugar free jam were prepared using pineapple and banana. These were Pineapple and Palayankodan (50:50), Pineapple and Njalipoovan (75:25) and Pineapple and Karpooravalli (75:25). The combinations were selected based on the physicochemical as well as sensory qualities of 13 combinations of normal jam samples prepared. Sucralose and sorbitol were used as sweeteners instead of sugar. Malto-dextrin was also added to get the bulkiness of jam. Physicochemical parameters like pH, titratable acidity, TSS, ascorbic acid, moisture, ash, etc. were analysed. Details of results obtained are given below. pH and Titratable Acidity The pH and titratable acidity values of sugar free jam samples were given in Table 4.14. pH values ranged 3.42 to 3.69, while titratable acidity from 0.49 to 0.56% CA. The values did not show much variation. These values were somewhat in accordance with the observations of Muhammad et al. (2008) in diet apple jam, Correa et al. (2011) in guava jam. Table 4.14. pH and Titratable Acidity of Diabetic friendly jam Sample
pH (27°C)
Acidity (% CA)
D1
3.69
0.49
D2
3.42
0.56
D3
3.53
0.56
Ascorbic Acid Ascorbic acid content (Table 4.15) of diabetic friendly jams was approximately similar to values observed in normal jam of same proportion. From this it is clear that replacement of sugar with any other sweetener having low calorie value does not affect the ascorbic acid content of jam. These results were more or less similar with study of Muhammad et al. (2008) in diet apple jam.
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Table 4.15. Ascorbic acid Content of Diabetic Friendly Jam Sample
Ascorbic acid (mg/100g)
D1
18.18
D2
18.18
D3
24.24
Total Soluble Solids TSS content (Fig. 4.9) of prepared sugar free jam showed slight differences in value compared to the same proportion of normal jam. The values were approximately similar with the findings of Youssef and Mousa (2012) in Baladi rose petals jam. But findings of Muhammad et al. (2008) in diet apple jam, Correa et al. (2011) in guava jam were less compared to these values.
Fig. 4.9. TSS Content of Sugar Free Jam Where, D1 = Pineapple: Palayankodan (50:50)
D2 = Pineapple: Njalipoovan (75:25)
D3 = Pineapple: Karpooravalli (75:25) Moisture Moisture content (Table 4.16) showed almost similar range of values with normal jam of same proportion. It was highest in D2 and lowest in D3. These values were not in accordance with the observations of Muhammad et al. (2008) in diet apple jam, Correa et al. (2011) in 68
guava jam, while approximately equal to the findings of Youssef and Mousa (2012) in Baladi rose petals jam. Table 4.16. Moisture Content of Sugar Free Jam Sample
Moisture (%)
D1
16.07
D2
19.85
D3
10.52
Ash Ash content (Fig. 4.10) values of sugar free jam was in the same range as of normal jam samples. The values ranged from 0.51 to 0.62%. Findings of Correa et al. (2011) in guava jam was similar with these values.
Fig. 4.10. Ash Content of Sugar Free Jam Where, D1 = Pineapple: Palayankodan (50:50)
D2 = Pineapple: Njalipoovan (75:25)
D3 = Pineapple: Karpooravalli (75:25)
4.2. Sensory Evaluation Sensory evaluation of both normal as well as diabetic friendly jam samples were conducted based on 9 point hedonic scale. The sensory parameters include colour, flavour, texture, taste, sweetness and overall acceptability. Nine untrained panellists were selected for
69
sensory evaluation. After sensory evaluation normal and diabetic friendly jam samples were compared based on sensory parameters. Details of analyses were given below.
4.2.1. Jam Flavour, Taste and Sweetness Flavour acceptability (Table 4.17) of jam samples was highest in J1 due to strong pleasant flavour and distinct aroma of pineapple fruit and lowest in J13 due to the distinct flavour of banana which is not suitable for jam. The values ranged from 4.3 to 7.2. Taste acceptability was maximum for J10 which was at par with J1 and lowest in J4. The values were ranged from 5.2 to 7.6. Sweetness score of prepared jam was maximum for J3 par with J10 and J11. The sweetness depends upon the amount of sugar added as well as the sugar content of fruits used. The values were ranged from 5.5 to 7.4. These observations were somewhat similar with the findings of Patel and Naik (2013) in pineapple and banana jam, Shakir et al. (2008) in apple and pear mixed fruit jam. Table 4.17. Sensory Score of Flavour, Taste and Sweetness of Jam Sample
Flavour
Taste
Sweetness
J1
7.2
7.5
7.2
J2
6.1
6.5
7.1
J3
6.0
6.5
7.4
J4
5.2
5.2
6.1
J5
5.1
6.2
6.5
J6
6.6
6.5
6.5
J7
5.3
5.6
5.7
J8
5.7
6.5
6.8
J9
4.6
5.8
6.1
J10
6.6
7.6
7.3
J11
6.1
7.0
7.3
J12
5.1
5.7
6.3
J13
4.3
5.5
5.5
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Colour, Texture and Overall Acceptability Colour acceptability (out of 9 points) of jams (Table 4.18) was found highest in J1 and J10 due to the maximum concentration of pineapple pulp that have golden yellowish colour and lowest in J4 which was at par with J13 and J9. The values ranged from 4.3 to 8.2. Colour is one of the most important parameter that determines the acceptability at first sight. Texture acceptability of prepared jam was found highest in J3 which was at par with J8 and lowest in J13 which was at par with J5 andJ12. The texture of jam samples depend upon the blending effect of both fruits which in turn responsible for the gelling and firming of softened finished product. The scores ranged from 5.2 to 7.2. The overall acceptability score was highest in J10 due to the combination of all other sensory parameters like colour, flavour, taste, sweetness etc. followed by J1 and lowest in J13. The values ranged from 8.0 to 5.3. The observations were similar to the findings of Patel and Naik (2013) in pineapple and banana jam, Priya et al. (2010) in mixed fruit jam and Relekar et al. (2010) in sapota jam. Table 4.18. Sensory Score of Colour, Texture and Overall Acceptability of Jam Sample
Colour
Texture
Overall Acceptability
J1
8.2
6.5
7.7
J2
6.2
6.5
6.7
J3
5.5
7.2
6.8
J4
4.3
5.6
5.4
J5
5.2
5.3
5.8
J6
7.0
6.2
7.1
J7
5.0
5.6
5.5
J8
5.8
7.0
7.0
J9
4.7
5.6
5.5
J10
8.2
6.6
8.0
J11
6.4
6.5
6.7
J12
5.6
5.4
5.8
J13
4.4
5.2
5.3
71
72
Fig. 4.11. Sensory values of different proportions of pineapple and banana jam
4.2.2. Diabetic Friendly Low-calorie Jam Flavour, Taste and Sweetness Flavour, Taste and Sweetness acceptability was highest in D 2 and lowest in D1. Flavour scores of diabetic friendly jam were almost similar with the scores of normal jam. Taste scores also in accordance with normal jam scores except in D 3. Much variation was observed in case of sweetness scores except in D 2. The observations were comparatively less with the findings of Youssef and Mousa (2012) in Baladi rose petals jam, Muhammad et al. (2008) in diet apple jam. Table 4.19. Flavour, Taste and Sweetness Score of Sugar Free Jam Sample
Flavour
Taste
Sweetness
D1
6.0
6.0
6.0
D2
6.5
6.7
6.7
D3
6.3
6.0
6.3
Colour, Texture and Overall Acceptability The colour acceptability score was highest in D 2 followed by D3 and D1. The values were almost similar with the values obtained for same proportion of normal jam except in D 3.
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Texture acceptability was highest in D1 and lowest in D3. Texture scores were slightly less compared to scores of normal jam. Overall acceptability score of diabetic friendly jam was comparatively less than same proportion of normal jam. The decrease in acceptability may be caused by the replacement of sucrose with other sweeteners or by the differences in other sensory parameters compared to normal jam. These observations were comparatively less with the findings of Youssef and Mousa (2012) in Baladi rose petals jam, Muhammad et al. (2008) in diet apple jam. Table 4.20. Colour, Texture and Overall Acceptability Score of Sugar Free Jam Sample
Colour
Texture
Overall Acceptability
D1
5.3
6.3
6.0
D2
7.3
6.0
6.7
D3
5.5
5.5
6.3
Fig. 4.12. Average sensory score for sugar free jam prepared using 50:50 (Palayankodan), 75:25 (Njalipoovan) and 75:25 (Karpooravalli)
4.3. Comparison of Normal and Sugar – Free Jam Comparison of physicochemical as well as sensory evaluation of normal jam with sugar free jam showed both similarities and dissimilarities. The physicochemical parameters of sugar free jam were almost similar with same proportion of normal jams prepared. It means
74
replacement of sucrose with any other sweetener does not much affect the most of the physicochemical parameters. Sensory scores of Pineapple: Palayankodan = 50:50 (D1), Pineapple: Njalipoovan = 75:25 (D2) were almost similar with the same proportion of normal jam. But these scores were highly varying in case of Pineapple: Karpooravalli = 75:25 (D3) with same normal jam. Comparison D3 with same proportion of normal jam is given in Fig. 4.13. From comparison it was clear that acceptance of pineapple and Karpooravalli sugar free jam was less compared to normal jam. In case of normal jam this sample was highly preferred by consumers, while acceptance was comparatively less in sugar free jam. This may be due to the taste difference caused by the replacement of sucrose with sweeteners like sucralose and sorbitol.
Fig. 4.13. Comparison of overall acceptability score of 75:25 (Karpooravalli) sugar and sugar-free Jam
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5. SUMMARY AND CONCLUSION
From the observations of the study ‘utilization of overripe discardable fruits of pineapple and banana for jam preparation’ the following results can be summarized. 1. It was possible to prepare value added products like jam successfully from overripe discarded fruits of pineapple and banana. All three banana varieties viz. Palayankodan, Njalipoovan and Karpooravalii used in this study were almost similarly effective and acceptable for jam preparation in combination with Vazhakulam pineapple (Mauritius var.). Physicochemical analysis of fruits showed that banana varieties possessed higher values in most parameters except ascorbic acid, titratable acidity, moisture and reducing sugar. 2. Altogether 13 combinations of jams were prepared using pineapple and banana and their physicochemical and sensory parameters were analyzed. The results showed very slight differences in values for titratable acidity, ash content, reducing and non-reducing sugar. The values of total soluble solids and total sugar content of these samples were very close to each other. Based on all the sensory properties, most preferred samples were pineapple jam and combination of 75:25 (Karpooravalli). 3. Three ideal proportions of pineapple and banana mix selected mainly based on their sensory parameters were 50:50 (Palayankodan), 75:25 (Njalipoovan) and 75:25 (Karpooravalli). 4. The same treatment combinations were further utilized for sugar-free jam preparation by replacing sugar with sucralose and sorbitol. These samples provided almost same intensity of sweetness with low-calorie compared to the same proportion of normal jams. 5. Physicochemical parameters were analysed and compared with normal jam samples. Values of physical as well as chemical properties of diabetic friendly jams were somewhat identical with normal jams. Total soluble solids were comparatively less than that of normal jams. Sensory scores of most of the parameters were relatively less compared to normal jams. Some parameters showed similarity in scores. The overall consumer acceptance was higher for 75:25 (Njalipoovan) in sugar-free jam category. 6. The overall consumer acceptance was higher for 75:25 (Karpooravalli) in normal jam, while most of the people preferred 75:25 (Njalipoovan) in sugar-free jam category based on overall acceptance.
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Conclusively, even though the physicochemical properties of both normal as well as diabetic friendly low-calorie jam samples were almost identical, higher consumer preference was for sugar included jams compared to diabetic friendly jams. Superior preference was for 75:25 (Karpooravalli) in normal jam and 75:25 (Njalipoovan) in sugar-free jam category based on overall consumer acceptability. Finally, over ripe fruits of pineapple and banana can be effectively used for the preparation of value added products like jam that can minimize post harvest losses of these fruits.
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APPENDIX
APPENDIX -1 Factors for 10 ml of Fehling’s solution to be used with Lane-Eynon volumetric method Titre in ml
Invert sugar
Titre in ml
(no sucrose)
Invert sugar (no sucrose)
15
50.5
33
51.7
16
50.6
34
51.7
17
50.7
35
51.8
18
50.8
36
51.8
19
50.8
37
51.9
20
50.9
38
51.9
21
51.0
39
52.0
22
51.0
40
52.0
23
51.1
41
52.1
24
51.2
42
52.1
25
51.2
43
52.2
26
51.3
44
52.2
27
51.4
45
52.3
28
51.4
46
52.3
29
51.5
47
52.4
30
51.5
48
52.4
31
51.6
49
52.5
32
51.6
50
52.5
Association of Official Agricultural Chemists, Official methods of analysis. 8 th Edn., p. 906, Washington, D.C. 1955.
APPENDIX-2 Temperature Corrections for the Standard Model of Sugar Refractometer Calibrated for 20°C Percentage of dry substance Temperature
5
10
15
20
25
30
35
40
45
50
55
60
65
70
Subtract from dry-substance percentages 15°C
.29
.31
.33
.34
.34
.35
.36
.37
.37
.38
.39
.39
.40
.40
16
.24
.25
.26
.27
.28
.28
.29
.30
.30
.30
.31
.31
.32
.32
17
.18
.19
.20
.21
.21
.21
.22
.22
.23
.23
.23
.23
.24
.24
18
.13
.13
.14
.14
.14
.14
.15
.15
.15
.15
.16
.16
.16
.16
19
.06
.06
.07
.07
.07
.07
.08
.08
.08
.08
.08
.08
.08
.08
Add to dry-substance percentages 21
.07
.07
.07
.07
.08
.08
.08
.08
.08
.08
.08
.08
.08
.08
22
.13
.14
.14
.15
.15
.15
.15
.15
.16
.16
.16
.16
.16
.16
23
.20
.21
.22
.22
.23
.23
.23
.23
.24
.24
.24
.24
.24
.24
24
.27
.28
.29
.30
.30
.31
.31
.31
.31
.31
.32
.32
.32
.32
25
.35
.36
.37
.38
.38
.39
.40
.40
.40
.40
.40
.40
.40
.40
26
.42
.43
.44
.45
.46
.47
.48
.48
.48
.48
.48
.48
.48
.48
27
.50
.52
.53
.54
.55
.55
.56
.56
.56
.56
.56
.56
.56
.56
28
.57
.60
.61
.63
.63
.64
.64
.64
.64
.64
.64
.64
.64
.64
29
.66
.68
.69
.71
.72
.73
.73
.73
.73
.73
.73
.73
.73
.73
30
.74
.77
.78
.79
.80
.80
.81
.81
.81
.81
.81
.81
.81
.81
Proceedings of the Ninth Session of the International Commission for Uniform Methods for Sugar Analysis, London. 1936.
