REFRIGERATION STORAGE STUDIES OF STRAWBERRY JUICE WITH TSS OF 7.5 AND 20.5 O BRIX TREATED WITH SODIUM BENZOATE AND POTASSIUM SORBATE

Transcription

1 Sarhad J. Agric. Vol.29, No.3, 2013 REFRIGERATION STORAGE STUDIES OF STRAWBERRY JUICE WITH TSS OF 7.5 AND 20.5 O BRIX TREATED WITH SODIUM BENZOATE AND POTASSIUM SORBATE SHAKOOR WISAL 1 *, ALAM ZEB 1, MUHAMMAD AYUB 1 and IHSANULLAH 2 1 Department of Food Science and Technology, The University of Agriculture Peshawar - Pakistan 2 Nuclear Institute for Food and Agriculture, Tarnab, Peshawar - Pakistan *Correspondence author: swisal@aup.edu.pk ABSTRACT Research was carried out to investigate the effect of different sucrose concentrations and chemical preservatives (combined doses) at refrigeration temperature (4-10 o C) on physicochemical and sensory attributes of strawberry juice stored for one year. The samples were numbered as, T R24 =Strawberry juice (7.5 brix) - no preservatives (control), T R25 =Strawberry juice (7.5 brix) with 0.1% sodium benzoate, T R26 =Strawberry juice (7.5 brix) with 0.1% potassium sorbate, T R27 =Strawberry juice (7.5 brix) with 0.05% sodium benzoate+0.05% potassium sorbate, T R28 =Strawberry juice (20.5 brix) - no preservatives (control), T R29 =Strawberry juice (20.5 brix) with 0.1% sodium benzoate, T R30 =Strawberry juice (20.5 brix) with 0.1% potassium sorbate, T R31 =Strawberry juice (20.5 brix) with 0.05% sodium benzoate +0.05% potassium sorbate. Maximum increase in total soluble solids (TSS) content occurred in T R25 and T R26 (20%) while T R29, T R30 and T R31 showed similar increase i. e. (9.75%). Maximum decrease in ph content occurred in T R24 (19.65%) while minimum decrease was observed in T R31 (10.27%). Maximum increase in titratable acidity occurred in T R24 (145.92%) followed by T R28 (136.19%) while minimum increase occurred in T R31 (101.90%) followed by T R29 (103.80%). Maximum ascorbic acid decreased in T R24 (88.81%) followed by T R28 (84.26%) while minimum decreased was observed in T R31 (70.27%). Maximum increase in reducing sugar was recorded in T R30 (26.49%) while minimum increase occurred in T R27 (19.65%). Maximum decrease in non reducing sugar was occurred in T R28 (89.84%) while minimum decrease occurred in T R27 (26.76%). Maximum decrease in color was recorded for T R24 (37.50%) followed by T R28 (31.25%). Flavor deterioration occurred in control samples and maximum decrease was observed in T R24 (87.50) followed by T R28 (75%) while concentrated samples less loss in flavor during storage. Comparatively better consistency was recorded by sweetened juice. Among all the treatments T R24 and T R28 were during storage while T R31 was found most effective followed by T R29 which showed better storage stability than other samples. Keywords: Strawberry juice, benzoate, sorbate, sucrose, refrigeration temperature. Citation: Wisal. S., A. Zeb., M. Ayub and Ihsanullah Refrigeration storage studies of strawberry juice with TSS of 7.5 and 20.5 o brix treated with sodium benzoate and potassium sorbate. Sarhad J. Agric. 29(3): INTRODUCTION Strawberry (Fragaria sp.) belongs to the family Rosaceae. It is one of the most important fruit among the berries (Sharma et al. 2009). It is thought that berries are important against several types of cancers (Navindra and P.Seeram. 2008). It is grown in many countries of the world, but is grown widely in the United States, Japan, Mexico, Italy, Lebanon (Childer, 1983) while some are grown widely which are pleasant in taste but smaller in size (Ensminger et al. 2007). It is more than any other large-scale, including fruits, grapes (Childer, 1980). Gradually grown in Pakistan because of its scope in the future is bright for farmers and fruits can be traced maximum economic benefit to farmers. There are certain factors which effect the production of strawberry for example scientifically grown strawberries give higher production than conventional cultivation (Tonture et al. 2009). Strawberries require low chilling requirements, and can be successfully grown crop in the tropics and subtropics. Strawberry fruit mature in a short period of time which is 30 to 40 days, highly perishable and must be consumed soon after picking. The fruit must be handled carefully as there are chances of deterioration during transportation to other markets (Amin, 1996). Strawberries are the first fresh fruit in the market during the spring. Because of the delicious flavor and attractive color and structure of the format, its demand is growing, not only in Pakistan but also in other parts of the world. It is consumed as fresh and some products are also prepared from it. Several products are prepared from it such as purees, jam, juice and wine etc. (Sharma et al. 2009). The fruit is firm, red and sweet. More than 50% of sucrose in strawberry is glucose. Fruit contains citric acid, and often some malic acid. The red color of fruit is due to the presence of anthocyanin pigment. Volatile esters responsible for many of the fruit flavor are found

2 Shakoor Wisal, et al. Refrigeration storage studies of strawberry juice with TTS of in it. Strawberry is low caloric fruit and provides less energy and a potential source of vitamin C, fiber and provides more vitamin C than oranges. The main components of fruit, vitamin C in strawberries is (64.0 mg), water (91.75 g) and protein (0.61 g), fat (0.37 g) and carbohydrate (7.02 g), fiber (2.3 grams), calcium (14.0 mg) and potassium (166.0 mg/160 g), respectively, and vitamin A 27IU. Ranging in ph from helps in achieving stability of color. Acidity ranges from 0.58 to 1.35% that contributes to excellent flavor. TSS is in the range 7.5 up to 11.5%, and is ideal for juice called for in the market. Soluble solids / acid ratio from 8.52 to are a good balance of sweet tart flavor. In the past decade there has been a significant increase in the demand for strawberries because the juice to have excellent flavor with an attractive color but little change in spoilage of the fruit. Due to the lack of other storage facilities to keep the product in the form of raw materials, this study has begun to take advantage of the fruit is very perishable in the form of juice, several products are prepared to extend shelf life with different preservatives refrigeration temperature. Potassium sorbate and sodium benzoate can maintain the good quality of fruit juices during Storage (Ayub et al. 2010). It is hoped that these results will help beverage industries to take advantage of this fruit juice to prepare with the shelf stability and the growing demand for consumer goods. This offer high-yield income for farmers, and will improve national economy. MATERIALS AND METHODS Fresh mature and sound strawberries were purchased from the local fruit market of Peshawar and were brought to Food Processing and Analytical Laboratory of the Department of Food Science and Technology, The University of Agriculture Peshawar, Pakistan where research work was carried out. The strawberries were washed followed by sorting, the juice was extracted using juice extracting machine. The samples were numbered as, T R24 =Strawberry juice (7.5 brix) - no preservatives (control), T R25 =Strawberry juice (7.5 brix) with 0.1% sodium benzoate, T R26 =Strawberry juice (7.5 brix) with 0.1% potassium sorbate, T R27 =Strawberry juice (7.5 brix) with 0.05% sodium benzoate+0.05% potassium sorbate, T R28 =Strawberry juice (20.5 brix) - no preservatives (control), T R29 =Strawberry juice (20.5 brix) with 0.1% sodium benzoate, T R30 =Strawberry juice (20.5 brix) with 0.1% potassium sorbate, T R31 =Strawberry juice (20.5 brix) with 0.05% sodium benzoate % potassium sorbate. The juice was filled in glass bottle, sealed and stored at refrigeration temperature (4-10 C) for a period of one year. Physico-chemical Analysis The total soluble solids (TSS) were determined using Abbe refractometer at ambient temperature (AOAC, 2000). Inolab digital ph meter was used for ph determination. Acidity was determined by dissolving a known weight of sample in distilled water and titration against 0.01 N NaOH using phenolphthalein as indicator (Srivastava and Sanjeev, 2003). Ascorbic acid was determined by the direct colorimetric method using 2, 6- dichlorophenolindophenols as decolorizing agent by ascorbic acid in sample extract and in slandered ascorbic acid solution (AOAC, 2000). Reducing and non-reducing sucrose was determined by lane Eynon method (AOAC, 2000). Sensory Evaluation A panel of ten judges were selected from staff and students of food science department evaluated the product fortnightly for color, flavor, consistency and overall acceptability by the method of Larmond (1977) using a scale from 1 to 9, where 1 represented extremely disliked and 9 represent extremely liked. Statistical Analysis The data obtained was subjected to statistical analysis using RCBD (Randomized Complete Block Design) and the means were compared by using LSD (Least Significant Difference) test (Steel and Torrie, 1980). For all the analyses, the alpha error was set at 0.05%. RESULTS AND DISCUSSION Chemical Analysis Results indicated that storage period and temperature had significant effect on total soluble solids (TSS) os strawberry juice during storage. Maximum increase occurred in T R25 and T R26 (20.00%) followed by T R27 (13.33%) while T R29, T R30 and T R31 showed similar increase i. e. (9.75%) during storage. Decrease occurred in T R24 and T R28 during storage (Table 1). These results are in agreement with the results obtained by Zeb et al. (2009) during preservation of grape juice stored at room temperature for one month preserved with sodium benzoate and potassium sorbate. Similar results were obtained by Hussain et al.(2011) during storage of apple and apricot blended juice storage at refrigeration temperature for three months. Increase in total soluble solids may be due to break down

3 Sarhad J. Agric. Vol.29, No.3, of polysaccharides into monosaccharide and oligosaccharides while decrease may be due to fermentation of sugars into ethyl alcohol, carbon dioxide and water. During storage maximum decrease in ph content was observed in T R24 (19.65%) followed by T R28 (16.94%) while minimum decrease was observed in T R31 (10.27%) followed T R27 (10.82%) (Table 2). Similar results were recorded by Mehmood et al. (2008) who studied the effect of pasteurization and chemical preservatives on the quality and shelf stability of apple juice stored at ambient temperature for three months. During storage of apple and apricot blended juices storage, preserved with sodium benzoate at refrigeration temperature for three months by Hussain et al. (2011), decrease in ph was recorded. Decrease in ph may be due to conversion of pectin into pectenic acid, which increases acidity and decreases ph of the juice. Storage and treatments has a significant effect on the titratable acidity of strawberry juice. Maximum increase was observed in T R24 (145.92%) followed by T R28 (136.19%) while minimum increase was observed in T R31 (101.90%) followed by T R29 (103.80%) (Table 3). Similarly increase in titratable acidity was observed by Zeb et al. (2009) during preservation of grape juice with sodium benzoate and potassium sorbate, stored at room temperature for one month storage period. The results of Ayub and Bilal (2001) are in agreement with our results, who observed an increase in acidity of pomegranate syrup, preserved under different light conditions and different packaging materials at room temperature for storage period of four months. This increase might be due to acidic compounds formed by degradation or oxidation of reducing sugar and high temperature. Increase in titratable acidity may be due to the breakdown of pectin into pectinic acid or due to the formation of acid by the breakdown of polysaccharides or oxidation of reducing sugars. Ascorbic acid is the most difficult vitamin to be preserved during storage. As it is the least stable vitamin, it decreases in the product during storage (Table 4). Maximum decrease was observed in T R24 (88.81%) followed by T R28 (84.26%) while minimum percent decrease was observed in T R31 (70.27%) followed by T R29 and T R30 (72.02%) (Table 4). The results are in agreement with the findings of Zeb et al. (2009) during preservation of grape juice with sodium benzoate and potassium sorbate, stored at room temperature for one month storage period, who observed decrease in ascorbic acid content of grape juice. The results of Ayub and Bilal (2001) are in agreement with our results, who observed decrease in ascorbic acid content of pomegranate syrup, preserved under different light conditions and different packaging materials at room temperature for storage period of four months. The losses may be due to oxygen present in the product and headspace of the package. Sugars are the most important constituent of fruit product and are essential factor for the flavor of the food product and also act as a natural food preservative. Results showed that reducing sugars increased in all samples in which maximum increase was observed in T R30 (26.49%) followed by T R29 (26.24%) while minimum increase was observed in T R27 (19.65 %) followed by T R25 (20.34%) while control samples i. e. T R24 and T R28 showed decrease during storage (Table5). Mehmood et al. (2008) observed an increase in reducing sugar of apple juice preserved with chemical preservatives stored at ambient temperature for three months. Increase in reducing sugar of apple and apricot blended juice, preserved with sodium benzoate at refrigeration temperature for three months, and was observed by Hussain et al. (2011). This increase in reducing sugar might be due to conversion of sucrose to reducing sugars (glucose and fructose) primarily due to acids and higher temperature. Maximum decrease in non reducing sugar was observed in T R28 (89.84%) followed by T R24 (83.09%) while minimum decrease was observed in T R27 (26.76%) followed by T R25 (28.16%) (Table 6). Mehmood et al. (2008) observed decrease in non reducing sugar of apple juice preserved with chemical preservatives stored at ambient temperature for three months. Increase in reducing sugar of apple and apricot blended juice, preserved with sodium benzoate at refrigeration temperature for three months, was observed by Hussain et al. (2011). This decrease in non reducing sugar might be due to conversion of sucrose to glucose and fructose, primarily due to increase in acidity and high storage temperature and storage period length. Sensory Evaluation The analysis of our data showed that storage period and treatments had a significant effect on sensory attributes (color, flavor, consistency and overall acceptability) of the strawberry juice. It was recorded that control samples were spoiled soon after storage and resulted in producing off flavor, maximum loss in color, consistency and overall acceptability while the treated samples retained comparatively better quality for the whole storage period. Better color was retained by the treated samples (Table 7). Off flavor was produced in control samples which may be due to fermentation process in which ethyl alcohol, carbon dioxide and water were produced (Table 8). Better consistency was recorded by treated samples especially by those samples which were concentrated with sugar (Table 9). Data showed that all the samples were acceptable even after one year of storage period (Table 10). The results are in agreement with the findings of Zeb et al. (2009) during preservation of grape juice with sodium benzoate and potassium sorbate, stored at room temperature for one month storage period, who observed decrease in color of

4 Shakoor Wisal, et al. Refrigeration storage studies of strawberry juice with TTS of grape juice. The results of Ayub and Bilal (2001) are in agreement with our results, who observed decrease in flavor of pomegranate syrup, preserved under different light conditions and different packaging materials at room temperature for storage period of four months. These results are in agreement with findings of Nilugen and Mahendran (2010), who observed decrease in consistency of ready to serve beverages prepared from palmyrah fruit pulp and stored at room temperature for six months. CONCLUSION AND RECOMMENDATIONS From our study it was concluded that sugar concentration, combination of preservatives and storage temperature play a positive role in extending the shelf life of strawberry juice. It was concluded that T R24 =Strawberry juice (7.5 brix) - no preservatives (control) and T R28 =Strawberry juice (20.5 brix) - no preservatives (control) were rejected while T R31 =Strawberry juice (20.5 brix) with 0.05% sodium benzoate % potassium sorbate followed by T R29 =Strawberry juice (20.5 brix) with 0.1% sodium benzoate maintained better quality stored at refrigeration temperature for one year period. 1. Other packaging materials (glass bottles, cans, jars) effect should be studied. 2. Other sucrose concentrations should be used for strawberry juice preparation. 3. Effect of other preservatives is to be studied. 4. Same experiments work should be repeated per other fruits juices preservation. Table 1. Effect of storage at refrigeration temperature ( C) on TSS of strawberry juice samples. TSS (Total Soluble Solids) content in juice T R * b T R a T R a T R a T R * b T R a T R a T R a Table 2. Effect of storage at refrigeration temperature ( C) on ph of strawberry juice samples ph Value T R a T R a T R a T R ab T R c T R ab T R a T R ab Table 3. Effect of storage at refrigeration temperature ( C) on acidity % of strawberry juice samples

5 Sarhad J. Agric. Vol.29, No.3, Acidity % content of juice. T R c T R d T R d T R d T R c T R d T R d T R d Table 4. Effect of storage at refrigeration temperature ( C) on Ascorbic Acid of strawberry juice samples Ascorbic acid content T R T R T R T R T R T R T R T R Table 5. Effect of storage at refrigeration temperature ( C) on reducing sugar of strawberry juice samples Reducing Sugar content T R * 4.05 b T R a T R a T R a T R * b T R a T R a T R a Table 6. Effect of storage at refrigeration temperature ( C) on non-reducing sugar of strawberry juice samples Non Reducing Sugar T R c T R ab T R b T R ab T R b T R a T R a T R a Table 7. Effect of storage at ambient refrigeration ( C) on color of strawberry juice samples Color score rate

6 Shakoor Wisal, et al. Refrigeration storage studies of strawberry juice with TTS of T R T R T R T R T R c T R a T R a T R a Table 8. Effect of storage at refrigeration temperature ( C) on flavor of strawberry juice samples Flavor score rate T R T R T R T R T R T R T R T R Table 9. Effect of storage at refrigeration temperature ( C) on consistency of strawberry juice samples Consistency score rate T R T R T R T R T R T R T R T R Table 10. Effect of storage at refrigeration temperature ( C) on overall quality of strawberry juice samples Overall score rate T R T R T R T R T R T R T R T R REFERENCES Amin NU (1996). Evaluation of different strawberry cultivars for offseason production under plastic tunnel. P.I. M.Sc. (Hons) thesis, Department of Horticulture, Agricultural University. Peshawar, Pakistan. A.O.A.C Official methods of analysis Association of Official Analytical Chemist 13th edition. Washington, D.C. Ayub, M., J. Ullah, A. Muhammad and A. Zeb Evaluation of strawberry juice preserved with chemical preservatives at refrigeration temperature. Int J. Nut. Metab. 2(2):

7 Sarhad J. Agric. Vol.29, No.3, Ayub., M. and M. Bilal Khan Effect of different light conditions and colored glass bottles on the retention of quality characteristics of pomegranate syrup during storage at room temperature. Sarhad J. Agric. 17(4): Ensminger, A. H.,M.E. Ensminger, J. E Kondale and JRK Robson Foods and Nutriton Encyclopedia Pegus press Colvis, California. Hussain, I., A. Zeb and M. Ayub Evaluation of Apple and Apricot Blend Juice Preserved with Sodium Benzoate at Refrigeration Temperature. World J. Agric. Sci. 7(2): Larmond, Larmond E (1977). Method for sensory evaluation of food. Canada Dept. of Agriculture, Publ., 1286: Mehmood, Z., A. Zeb, M. Ayub, N. Bibi, A. Badshah and Ihsanullah Effect of Pasteurization and Chemical preservativeson the Quality and shelf stability of Apple Juice. Amer. J. Food Tech. 3(2): Navindra P. Seeram Berry Fruits for Cancer Prevention: Current Status and Future Prospects. J. Agric. Food Chem. 56: Nilugin, S.E. and T. Mahendran Preparation of ready-to-serve (RTS) beverage from palmyrah (Borassus flabellifer L.) fruit pulp. J. Agric. Sci. 5(2): Sharma, S., V. K. Joshi and G. Abrol An overview on strawberry [ Frageria x ananassa (Weston) Duchesne ex Rozier] wine production technology, composition, maturation and quality evaluation. Nat. Prod. Rad. 8(4): Srivastava RP, Sanjeev K, (2003). Fruit and vegetable preservation principles and practices: Important methods for analysis of Fruits?Vegetablesand their products. Third Revised and Enlarge Edition. International Book Distribution Co., Lucknow, India :363. Steel RGD, Torrie JH (1980). Principle and procedures of statistics. Mc Graw Hill Book Co. NY, U.S.A, 2nd ed, pp: Tönutare, T., U. Moor, K. Mölder and P. Pöldma Fruit composition of organically and conventionally cultivated strawberry "Polka". Agron. Res. (Special Issue II) U.S Dept. of Agriculture USDA (1998). Nutrient database for standard reference, (www oregon-strawberries. Org). Zeb, A, I. Ahmad, K. M.Ayub Grape juice preservation with benzoate and sorbate. J. Adv. Food. Sci. 31(1):17-21.