Development of a preserved product from underutilized passion fruit and evaluation of consumer acceptance

JOURNAL OF FOOD RESEARCH AND TECHNOLOGY Journal homepage: www.jakraya.com/journal/jfrt ORIGINAL ARTICLE Development of a preserved product from underutilized passion fruit and evaluation of consumer acceptance Sujata Jena Assistant Professor, College of Agricultural Engineering and Post Harvest Technology, Central Agricultural University, Ranipool -737135, Gangtok, Sikkim, India *Corresponding Author: Assistant Professor, College of Agricultural Engineering and Post Harvest Technology, Central Agricultural University, Ranipool-737135, Gangtok, Sikkim, India. Email:sujata_jena@hotmail.com Received: 21/07/2013 Revised: 11/09/2013 Accepted: 26/09/2013 Abstract In the present study, passion fruit jam; a new value added product was developed from underexploited passion fruit. The product was developed using different ratios of passion fruit skin pulp and passion fruit juice, sugar, and sodium bicarbonate. The developed jam was stored in glass and polypropylene (PP) jars for six months. The stored product was analyzed at various storage intervals for ph, TSS and sensory properties for determination of shelf life. From the sensory analysis, both glass products were found acceptable with high sensory scores to the trained panelists after six months where as mold growth was observed in PP packed samples after 5 months. Passion fruit jam developed with ratio of passion fruit juice to skin pulp of 1:1 was found more acceptable based on higher sensory scores of overall acceptability. Keywords: Passion fruit; jam; packaging material; skin pulp; sensory evaluation Introduction Passion fruit (Passiflora edulis) is an edible fruit which is widely grown in many tropical or sub-tropical areas including India. There are two important commercial varieties, purple passion fruit (Passiflora edulis), and yellow passion fruit (Passiflora edulis flavicarpa). The latter has larger fruits, more acidic juice and a less preferred flavour. The fruits are most suitable for processing at maturity when the outer skin has a smooth or slightly crinkled surface. The fruit is known for its unique musky, guava-like flavor and aroma which makes its pulp an important flavoring agent in drinks, desserts, sauces and many other foods. The fresh whole fruit has a very low shelf life of 1 week (Wu et. al., 2005). Because of this perishable nature passion fruits produced during a particular season results in a glut in the market and become scarce during other seasons. Moreover, its use is limited to fresh consumption, pulp (Wu et. al., 2005), juices and blended beverages (Deuel and Plotto, 2005) which can be stored for only 2-3 months. This opens up avenues for development of other value added preserves viz jams, jellies etc that can be stored for longer period. Jam and jellies are manufactured as one of the important fruit product in industries. Jam is a semisolid food made from not less than 45% (by weight) fruit and 55 % (by weight) sugar. This substrate is concentrated to about 65 % or above soluble solids. In addition to the pleasing taste of such preserved fruits, they possess substantial nutritive value also. Realizing the importance of fruit, as a cheap, highly nutritious foodstuff and because of its perishable nature and seasonally availability, it was deemed necessary to make a preserved product from passion fruit for human consumption, which would have a shelf life of 5-6 months. Passion fruit juice is a good source of ascorbic acid and carotenoids but poor in pectin content. A ph of

3.1 and adequate pectin in fruit juice is recommended for perfect jam setting (Verma, 2000; Vidhya and Narain, 2010). The low ph and low pectin content of passion fruit juice are the major hindrance in the preparation of pure passion fruit jam. These can be overcome by addition of suitable additives viz., sodium bicarbonate (Verma, 2000) and passion fruit skin pulp which is a very good source of pectin. The preserved product thus produced need proper packaging and quality analysis for determination of shelf life. Various packaging materials such as high density polyethylene (HDPE), polypropylene (PP) and glass are commonly used for packaging of jam. Since different packaging materials influence the quality of the stored products differently, study of the effect of packaging material on the quality parameters during storage is very much necessary. Consumer acceptance is the ultimate criterion for deciding the quality of a product. Sensory evaluation is required for knowing the consumers preferences and market acceptability of any food. It is useful for product development and further improvement since the important factors for a particular market can be identified and improved (Zhang and Litchfield, 1991). In light of the above, the present study was taken up to develop a preserved product viz., jam from passion fruit using passion fruit skin pulp as a pectin source. It was also aimed to study the effects of skin pulp content and packaging materials on the sensory and physico-chemical properties of the developed product. The consumer acceptance of the developed product was assessed through sensory evaluation. Materials and methods Preparation of raw materials: Fresh mature passion fruits and sugar were procured from local market. The fruits were washed thoroughly with water. Fruits were cut into half with stainless steel knife and the pulp was scooped out with a stainless steel spoon. Passion fruit juice was extracted by churning the pulp at low speed for about 1-2 minutes to avoid chipping of seeds in a food processor. The mixed contents were then filtered using a muslin cloth to extract the passion fruit juice. For preparation of passion fruit skin pulp, passion fruit skins (same quantity as that of skin pulp required) is boiled for approximately 30 minutes in water until the flesh is soft. Then the skins were removed from the water and the flesh was scooped out from the outer cuticle. The softened flesh is then mixed with water in the ratio of 2:1 until it forms a smooth paste. The water used for boiling the skins is used to make the paste as it contains the pectin washed out during boiling. The raw passion fruit juice was mixed with sodium bicarbonate at 0.015% to adjust the ph of the juice. The TSS and ph of passion fruit juice and skin pulp were tested using digital refractometer (ATAGO, India) and ph meter (Satorius, India) respectively. The moisture content of the products was measured as per standard chemical methods (Ranganna, 1987). Two types of packaging jars viz glass and polypropylene (PP) were used for packaging of the developed passion fruit jam. The glass and PP jars and lids were sterilized in hot water at 100 o C for 15 minutes. The jars were removed and turned upside down to drain the water inside. Development of passion fruit jam: Passion fruit jam was prepared by open pan evaporation method. The passion fruit juice, skin pulp, sugar and water were weighed separately before the starting of the concentration process. Prepared passion fruit juice and skin pulp were mixed and heated in a stainless steel pan on gas stove. Required quantity of water and sugar were added to the preheated mixture and heating was continued. The contents of the pan were stirred continuously to prevent sticking to the bottom of the pan. The heating was continued till the end point of jam was reached. The end point was established based on the final TSS of the jam i.e. 65-68 o Bx as measured using digital refractometer. The concentration process was about 12-15 minutes. Two types of jam were developed by varying the ratio of passion fruit juice to skin pulp. The prepared products were filled hot (80 o C) into pre-sterilized warm polypropylene (PP) and glass jars. The clean lids were placed on the jars and tightened. The jars were then inverted 12

to form a seal. The filled jam jars are then cooled naturally and stored under ambient conditions (average storage temperature: 25±1.5 o C and rela- tive humidity: 74±2%) for six months. Fig. 1 depicts the process flow chart of passion fruit jam. Passion fruit Sorting and washing/cleaning Halving Fruit juice extraction Juice Skin Boiling of skin with equal amount of water Addition of sodium bicarbonate @ 0.015% Removal of soft white portion of the skin and mashing with water Mixing Skin pulp Sugar Boiling up to a concentration of 65-68 o Bx Water Jam Filling in glass and PP bottles (pre-sterilized) Labelling and Storage Fig 1: Process flow chart for Passion fruit jam 13

Two independents treatments viz ratio of passion fruit juice to passion fruit skin pulp and type of packaging material were selected at various levels. Table 1 lists the levels of treatments given. A Full factorial experimental design with three replications was followed. The developed products were analyzed for ph, TSS and sensory evaluation at different storage intervals. Table 1 presents the storage intervals selected for analysis. Sensory evaluation: The two developed jam products were compared with the pure market jam viz., Pineapple jam (Brand: Sikkim supreme) based on sensory evaluation. Pineapple jam was selected as market product since no passion fruit jam is available in market. A fifteen member panelists (in the age group of 20-50 years consisting of both male and female) were selected for sensory evaluation. The criteria for the selection of the judges were that they had no food allergies, and were available and willing to participate on the test day. They were familiarized with the definitions of the quality attributes, the score sheet and method of scoring. They were also asked to take two short sniffs of the samples before tasting the sample and give the score for the aroma first in the scorecard. The samples were placed in white plastic/paper glasses, labeled and placed on benches in a way such that there was no interference between the panelists. Water was provided for the panelists to rinse their mouth after each taste. Puffed rice was also provided to the judges to have a bland taste in the mouth after each taste. Evaluation was based on colour, flavor, aroma, texture/mouthfeel, overall acceptability and buying intention. Scoring was based on nine point hedonic scale of 1-9 (1 = dislike extremely and 9 = like extremely). Results and discussion Two products viz passion fruit jam with two different ratios of passion fruit juice and skin pulps were developed. The samples were coded S1 for ratio of 2:1 and S2 for ratio of 1:1. The composition of the developed jam products are given in Table 2. In PP jar packed samples mold growth was observed after 5 months. Hence, the PP jar packed jam samples were discarded and could not be analyzed after 5 months. Effect of storage time, packaging material and composition on ph of passion fruit jam: Average ph values varied from 2.93±0.04 to 2.29±0.01 for S1 (2:1) where as the range was between 3.23±0.04 to 2.69±0.01 for different products during the storage period. Fig. 2 shows the variation in ph for samples S1 and S2 for PP and glass packed products. From Fig 2, a decrease in ph with storage time was observed for both S1 and S2. An increase in ph with increase in ratio of passion fruit juice to skin pulp was also noticed. A two factor ANOVA was carried out to find the effect of storage time and composition on the ph of the developed products. A significant decrease in ph (P<0.01) with increasing storage period was observed for all samples. Similar decrease in ph was reported in apple and pear mixed jam for a storage period of 3 months by Shakir et al. (2007) and in grape fruit apple marmalade by Ehsan et al. (2003). From the results of ANOVA, a significant effect (P<0.01) of composition (ratio of passion fruit juice to skin pulp) on ph was observed. The decrease in ph may be attributed to formation of free acids and pectin hydrolysis (Muhammad et. al., 2008; Hussain and Shakir, 2012). A single factor ANOVA was carried out to find the effect of packaging material on the ph variation with storage time. A p value between 0.76 and 0.88 (P>0.05) was observed for all samples. From, this it can be concluded that the effect of packaging material on the ph of jam is not significant. Effect of storage time, packaging material and composition on TSS of passion fruit jam: Average TSS values of three replications of developed passion fruit jam ranged from 66.6±0.28 to 62.25±0.21 for S1 (2:1) where as the range was between 67.8 ±0.28 and 63.2±0.4 for S2 (1:1) during the storage period. Fig. 3 depicts the variation in TSS of developed jam samples packed in glass and PP bottles. From this figure, a decrease in TSS with storage time was observed for both S1 and S2. 14

Table 1: Experimental design for passion fruit jam Independent variables No. of levels Levels Ratio of passion fruit juice to passion fruit skin pulp 2 1:1, and 2:1 Packaging materials 2 Glass, and PP Storage time, days 6 30, 60, 90, 120, 150 and 180 days Table 2: Composition of developed passion fruit jam Ingredients S1 S2 ph TSS, Bx Passion fruit juice, % 20 26.7 2.32±0.12 13.9±0.2 Passion fruit skin pulp, % 20 13.3 3.96±0.15 0.8±0.1 Sugar, % 50 50 Water, % 10 10 Sodium bicarbonate, % 0.015 0.015 A two factor ANOVA was carried out to find the effect of storage time and composition on the TSS of the developed products. A highly significant decrease in TSS (P<0.001) with increasing storage period was observed for all samples. Vidhya and Narain (2010) reported no changes in TSS of wood apple jam during a storage period of 3 months. Hossen et. al. (2009) also reported no effect of storage time on TSS of guava jelly during 210 days of storage in glass bottles. Shakir et al. (2007) reported increase in TSS in apple and pear mixed jam with storage time in a period of 3 months. Hence, no particular trend in TSS during storage of jam could be inferred from literature to compare with the present results. A decrease in TSS with increase in ratio of passion fruit juice to skin pulp was noticed from Fig. 3. From the results of ANOVA, a significant effect (P<0.001) of composition (ratio of passion fruit juice to skin pulp) on TSS was observed. A single factor ANOVA was carried out to find the effect of packaging material on the TSS variation with storage time. No significant effect of packaging material on the TSS of jam found which was established based on the p value between 0.26 and 0.61 (P>0.05) for all samples. Evaluation of sensory properties of passion fruit jam: The sensory scores of colour varied between 7.2±1.3 and 8.3±0.1 for S1 (ratio of passion fruit juice to skin pulp: 2:1) and between 7.8±0.7 and 8.5±0.5 for S2 (ratio of passion fruit juice to skin pulp: 1:1) during the entire storage duration. Colour values of sensory evaluation for market pineapple jam (S3) were in the range of 6.6±1.3 to 7.6±1.2 in the storage period of 6 months. S2 scored highest and S3 (market jam) scored lowest among the tested samples in colour scores during the entire storage period. The sensory scores for aroma varied between 7.2±1.3 and 8.5±0.8 for S1 (ratio of passion fruit juice to skin pulp: 2:1) and between 7.3±0.9 and 8.7±0.5 for S2 (ratio of passion fruit juice to skin pulp: 1:1) during the entire storage duration. Aroma values of sensory evaluation for market pineapple jam (S3) were in the range of 6.3±1.2 to 7.5±1.2 in the storage period of 6 months. S2 scored highest and S3 (market jam) scored lowest among the tested samples in aroma scores during the entire storage period The taste sensory scores varied between 6.7±2.7 and 8.5±0.6 for S1 (ratio of passion fruit juice to skin pulp: 2:1) and between 7.9±0.6 and 8.6±0.7 for S2 (ratio of passion fruit juice to skin pulp: 1:1) during the storage duration. 15

Fig 2: ph variation in stored jam products Fig 3: TSS variation in stored jam products 16

For market pineapple jam (S3), taste scores were in the range of 6.1±1.0 to 7.8±1.0 in the storage period. S2 scored highest and S3 (market jam) scored lowest in taste among the tested samples. The texture sensory scores varied between 7±1.6 and 8.6±0.7 for S1 (ratio of passion fruit juice to skin pulp: 2:1) and between 7.9±0.6 and 8.6±0.7 for S2 (ratio of passion fruit juice to skin pulp: 1:1) during the storage duration. For market pineapple jam (S3), texture scores were in the range of 6 ± 0.8 to 7.4±1.9 in the storage period. S2 scored highest and S3 (market jam) scored lowest in texture among the tested samples. Effect of storage time, composition and packaging material on sensory properties of passion fruit jam: A two factor ANOVA (Table 3) was carried out to find the effect of storage time and composition on the colour, aroma, taste and texture of the developed products. From Table 3, no significant effect of storage time (P = 0.3 to 0.6 >0.05) on colour, aroma, taste and texture of the developed passion fruit jam products was observed. Similar type of observation has been reported by Vidhya and Narain (2010) for wood apple jam during storage. Effect of jam composition (P = 0.2-0.5 >0.05) on colour, aroma, taste and texture of different jam products was also found non-significant. A single factor ANOVA was done to test the effect of packaging material on sensory scores of colour, aroma, taste and texture of jam products. From the results of ANOVA, P values >0.05 were observed for S1 and S2. This shows that there was no significant effect of packaging material on the colour of the jam products. Evaluation of consumer acceptance of the developed passion fruit jam: Table 4 records the variation in average sensory scores of overall acceptability for various developed passion fruit jam and market product stored under ambient conditions. The overall acceptability (OA) sensory scores varied between 7.3±0.9 and 8.6±0.6 for S1 (ratio of passion fruit juice to skin pulp: 2:1) and between 7.9±0.5 and 8.6±0.7 for S2 (ratio of passion fruit juice to skin pulp: 1:1) during the storage duration. For market pineapple jam (S3), OA scores were in the range of 5.8 ± 0.7 to 7.9 ±0.2 in the storage period. A single factor ANOVA (Table 5) was conducted to test the effect of composition on the overall sensory scores all three samples. From Table 5, a significant effect of composition with P value (0.001 to 0.003 <0.05) was observed for both glass and PP packed samples. Out of all the three samples tested, Sample S2 scored consistently higher values than S1 and S3 (market jam) scored lowest in OA among the tested samples. From these observations, sample S2 i.e. jam prepared with 1:1 ratio of passion fruit juice to skin pulp may be considered as the most acceptable jam by consumers. Sample S2 packed in glass jars were of acceptable quality after 6 months where as mold growth was observed in PP jar filled jam after 5 months. The TSS and ph of glass packed jam sample S2 after 6 months was 64.70±0.14 Bx and 2.69±0.01 respectively. These values were within the acceptable limits of TSS (65 Bx) and ph for jam. For PP jar filled jam sample S2, TSS and ph after 5 months were 63.2±0.4 Bx and 2.84±0.01 respectively. This TSS value is slightly lower than the desired value of 65 Bx. Hence, sample S2 packed in glass jars can be regarded as the most liked product by the consumers even after 6 months of storage. Conclusion Passion fruit jam was developed in the present study using passion fruit skin pulp in different ratios to passion fruit juice. The developed passion fruit jam were packed in PP and glass jars and stored at a temperature of 25±1.5 C and relative humidity: 74±2%. From the study, the decreasing effect of storage time on ph and TSS of stored products was found highly significant. A significant increase in ph was observed with increase in passion fruit juice content in the jam. A significant decrease in TSS with increased passion fruit juice content was observed. No significant effect of packaging material was found on ph and TSS of the developed products. Based on the high overall acceptability scores and acceptable TSS and ph values, passion fruit jam developed with the ratio of passion fruit juice to skin pulp of 1:1 and packed in glass jars was highly acceptable up to 6 months by consumers. 17

Table 3: Two factor ANOVA showing effect of storage times and jam composition on sensory properties through F-test at 95% confidence level ANOVA TABLE FOR COLOUR Packaging material: PP Storage time 0.480 5.000 0.096 0.828 0.580 a 5.050 Composition 0.338 1.000 0.338 2.914 0.068 a 6.608 Error 0.580 5.000 0.116 Total 1.398 11.000 Packaging material: Glass Storage time 0.547 6.000 0.091 1.576 0.297 a 4.284 Composition 0.385 1.000 0.385 6.650 0.063 a 5.987 Error 0.347 6.000 0.058 Total 1.279 13.000 ANOVA TABLE FOR AROMA Packaging material: PP Storage time 0.708 5.000 0.142 0.469 0.787 a 5.050 Composition 0.907 1.000 0.907 3.010 0.143 a 6.608 Error 1.508 5.000 0.302 Total 3.123 11.000 Packaging material: Glass Storage time 0.554 6.000 0.092 1.220 0.408 a 4.284 Composition 0.393 1.000 0.393 5.187 0.060 a 5.987 Error 0.454 6.000 0.076 Total 1.401 13.000 ANOVA TABLE FOR TEXTURE Packaging material: PP Storage time 0.274 5.000 0.055 0.631 0.687 a 5.050 Composition 0.521 1.000 0.521 5.998 0.058 a 6.608 Error 0.434 5.000 0.087 Total 1.229 11.000 Packaging material: Glass Storage time 0.957 6.000 0.160 0.920 0.539 a 4.284 Composition 0.875 1.000 0.875 5.048 0.066 a 5.987 Error 1.040 6.000 0.173 Total 2.872 13.000 Superscript a denotes not significant 18

Table 4: Overall acceptability scores for stored jam products Overall acceptability Storage time, days S1 (2:1) S2 (1:1) Market Glass PP Glass PP 0 7.9±1.0 7.9±1.0 8.6±0.7 8.6±0.7 7.8±1.2 30 7.6±1.0 7.8±0.8 8.4±0.5 8.4±0.7 7.3±1.6 60 8±0.9 7.7±1.0 8.5±0.7 8.5±0.7 6.8±1.0 90 8±0.5 8±0.7 8.3±0.8 7.9±0.5 7.1±1.2 120 7.5±0.9 7.3±0.9 8.4±1.1 8.2±0.9 5.9±0.7 150 8.6±0.6 8.3±0.6 8.3±0.9 8.1±0.5 5.8±0.7 180 8.5±0.9 8.5±0.4 7.9±0.2 Table 5: Single factor ANOVA showing effect of jam composition on overall acceptability through F-test at 95% confidence level ANOVA TABLE FOR OVERALL ACCEPTIBILITY Packaging material: PP Between groups 4.03 2 2.015 8.408 0.004 3.682 Within groups 3.595 15 0.240 Total 7.625 17 Packaging material: Glass Between groups 5.041 2 2.521 10.756 0.001 3.682 Within groups 3.515 15 0.234 Total 8.556 17 References Deuel CL and Plotto A (2005). Strawberries and Raspberries. In: Processing Fruits: Science and Technology, Eds. Diane M. Barrett, Laszlo P. Somogyi and Dr. Hosahalli Ramaswamy. CRC Press. Ehsan EB, Naeem ZP, Javed A and Nazir A (2003). Development, standardization and storage studies on grape fruit apple marmalade. Pakistan Journal of Food Science, 13 (3-4): 11-15. Hossen S, Kabir MS, Uddin MB, Rahman AKML and Mamun MRA (2009). Effect of different extractions of juice on quality and acceptability of guava jelly. Journal of Innovation and Development Strategy, 3(4): 27-35 Hussain I and Shakir I. 2012. Chemical and organoleptic characteristics of jam prepared from indigenous varieties of apricot and apple. World Journal of Dairy and Food Sciences, 5(1): 73-78. Muhammad A, Durrani Y, Zeb A, Ayub M and Ullah J (2008). Development of diet jam from apple grown in swat (nwfp). Sarhad Journal of Agriculture, 24 (3): 461-467 Ranganna S (1987). Handbook of analysis and quality control for fruit and vegetable products. Tata McGraw-Hill publications, New Delhi. Shakir I, Durrani Y, Hussainm I, Qazi IM and Zeb A (2007). Physicochemical analysis of apple and pear mixed fruit jam prepared from varieties grown in azad Jammu and Kashmir. International Journal of Food Safety, 9: 22-24 Verma LR (2000). Postharvest technology of fruits and vegetables: handling, processing, fermentation, and waste management, Volume 1, Indus Publishing, India. 19

Vidhya R and Narain A (2010). Development of preserved products (Jam and Fruit Bar) from under exploited wood apple Limonia acidissima fruits. African Journal of Food Science and Technology, 1(2): 51-57. Wu JS, Wu M, and Wei Y (2005). Tropical Fruits. In: Processing Fruits: Science and Technology, Eds. Diane M. Barrett, Laszlo P. Somogyi and Dr. Hosahalli Ramaswamy. CRC Press. Zhang Q and Litchfield JB (1991). Applying fuzzy mathematics to product development and comparison. Food Technology, 45 (7): 108-115. 20