Effect of benzoate, sorbate and citric acid on the storage stability of strawberry juice

Effect of benzoate, sorbate and citric acid on the storage stability of strawberry juice Shakoor Wisal 1, Muhammad Sohail 2,Manzoor Ahmad Mashwani 1,Zafar Hayat khan 1, Zahid Hussain 1 and Saqib Noor 3 1 Bacha Khan University, Charsadda, Pakistan 2 Pakistan Council of Scientific and Industrial Research Labs Complex Peshawar, Pakistan 3 The University of Agriculture, Peshawar, Pakistan ABSTRACT Corresponding author: msohail294@gmail.com This research was carried out to investigate the effect of different additives on the physicochemical and sensory attributes of strawberry juice stored at ambient temperature (20-25 o C) for three months. The samples were numbered as, T A12=Strawberry juice (7.5 brix) - no preservatives (control) and 0.1% citric acid, T A13=Strawberry juice (7.5 brix) with 0.1% sodium benzoate and 0.1% citric acid, T A14=Strawberry juice (7.5 brix) with 0.1% potassium sorbate and 0.1% citric acid, T A15=Strawberry juice (7.5 brix) with 0.05% sodium benzoate+0.05% potassium sorbate and 0.1% citric acid, T A20=Strawberry juice (30.5 brix) - no preservatives (control) and 0.1% citric acid, T A21=Strawberry juice (30.5 brix) with 0.1% sodium benzoate and 0.1% citric acid, T A22=Strawberry juice (30.5 brix) with 0.1% potassium sorbate and 0.1% citric acid, T A23=Strawberry juice (30.5 brix) with 0.05% sodium benzoate+0.05% potassium sorbate and 0.1% citric acid. Maximum increase in total soluble solids (TSS) occurred in T A20 (120%) while minimum change occurred in T A12 (66.67%). Maximum decrease in ph was recorded in T A12 (16.23%) followed by T A20 (12.08%) while minimum decrease was observed in T A23 (7.41%). Maximum increase in titratable acidity was observed in T A12 (127.38%) followed by T A20 (120.00%) while minimum increase was observed in T A23 (92.00%) followed by T A21 (96.00%). Maximum decrease in ascorbic acid was observed in T A12 (65.82%) while minimum decrease was observed in T A23 (40.56%) followed by T A21 (43.23%). Maximum increase in reducing sugar occurred in T A22 (27.82%) followed by T A21 (27.73%) while minimum increase occurred in T A15 (13.10%). Maximum decrease in non reducing sugar was observed in T A20 (90.47%) followed by T A12 (70.42%) while minimum decrease occurred in T A13 (11.26%). On the basis of overall sensory acceptability all the samples were rejected after sometime. Among all the treatments T A12 and T A20 were rejected soon after storage due to spoilage while T A123 followed by T A21 was found most effective but were also rejected after sometime. Key words: Strawberry juice, benzoate, sorbate, sucrose, ambient temperature. INTRODUCTION Strawberry (Fragaria sp.) belongs to the family Rosaceae and is grown throughout the world especially in those countries laying in tropical and sub tropical regions. It is the most important fruit among the berries (Sharma et al., 2009). Strawberries are highly perishable and must be consumed soon after picking. Strawberries are the first fresh fruit in the market during the spring. It is consumed mainly as fresh fruit and is also used in the form of treatment such as canned, cooked and sweetened such as jam, jelly and frozen whole berries (Hern andez et al., 2006). The fruit is firm, red and sweet. More than 50% of sugar 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 in it. Nutritionally strawberries 218

contain carbohydrate low-calorie and a potential source of vitamin C, fiber and provide more vitamin C than oranges. In the past decade there has been a significant increase in the demand for strawberries because the juice has excellent flavor with an attractive color. However little fluctuation in temperature results in damage and waste of fruits (Gontared et al., 1996). Potassium Sorbate is important in the preservation of juices during storage. Similarly Sodium Benzoate can also maintain the good quality of fruit juices during preservation (Ayub et al., 2010). It is numbered as E330 and if it is used in combination with other preservatives, then it gives good results (Wisal et al., 2013). Due to lack of other storage facilities to keep the product in the form of raw materials, this study was initiated. It is hoped that this study will help beverage industries to take advantage of this fruit, to prepare juice with the shelf stability and the growing demand for consumers. This will offer high-yield income for farmers and will improve the economy of Pakistan. 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. Before filling in glass bottles the juice was pasteurized. The treatments prepared were according to the given plan. T A12=Strawberry juice (7.5 brix) - no preservatives (control) and 0.1% citric acid, T A13=Strawberry juice (7.5 brix) with 0.1% sodium benzoate and 0.1% citric acid, T A14=Strawberry juice (7.5 brix) with 0.1% potassium sorbate and 0.1% citric acid, T A15=Strawberry juice (7.5 brix) with 0.05% sodium benzoate+0.05% potassium sorbate and 0.1% citric acid, T A20=Strawberry juice (30.5 brix) - no preservatives (control) and 0.1% citric acid, T A21=Strawberry juice (30.5 brix) with 0.1% sodium benzoate and 0.1% citric acid, T A22=Strawberry juice (30.5 brix) with 0.1% potassium sorbate and 0.1% citric acid, T A23=Strawberry juice (30.5 brix) with 0.05% sodium benzoate+0.05% potassium sorbate and 0.1% citric acid. The juice was filled in 250 ml glass bottles, sealed and stored at ambient temperature (20-25 C) for a period of three months. Physicochemical analysis Physicochemical analyses were carried out initially and after 15 days storage interval up to the successful completion of the study. Total soluble solids (TSS) were determined by using Abbe refractometer (AOAC, 2000). 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- dichlorophenol- indophenols dye as decolorizing agent (AOAC, 2000). Reducing and non-reducing sucrose was determined by lane Eynon method (AOAC, 2000). Sensory Evaluation A panel of ten judges selected from staff and students of food science department evaluated the product fortnightly for overall sensory acceptability by the method of Larmond (1977) using a scale from 1 to 9, where 1 represented extremely dislike and 9 represent extremely like. 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 Physicochemical Analysis On the basis of physicochemical analyses, results indicated that storage period and temperature had significant effect on total soluble solids (TSS) during storage (Table 1). Maximum increase occurred in T A20 (120%) followed by T A22 (98.18 %) while minimum increase was recorded in T A15 (9.33%). T A12 showed a decreasing trend and having 66.67% reduction in TSS after 3 months storage period. 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 also obtained by Hussain et al. (2011) who worked on the storage of apple and apricot blended juice at refrigeration temperature for three months. Increase in total 219

soluble solids may be due to break down of polysaccharides into monosaccharide and oligosaccharides while decrease may be due to fermentation of sugars into ethyl alcohol, carbon dioxide and water. Table 1: Effect of chemical preservatives on TSS of strawberry juice adjusted Table 2 shows effect of chemical preservatives on ph of strawberry juice stored at ambient temperature. During this storage maximum decrease in ph was observed in T A12 (16.23%) followed by T A20 (12.08%) while minimum decrease was observed in Initial 20 40 60 80 % Dec/Inc Mean TSS (Total Soluble Solids) T A12 7.5 4.1 4.0 4.0 2.5 66.67 4.420 b T A13 7.5 7.5 7.5 8.0 8.5 13.33 7.800 a T A14 7.5 7.5 7.5 8.0 8.5 13.33 7.800 a T A15 7.5 7.5 7.5 7.8 8.2 9.33 7.700 a T A20 1.10 1.85 2.12 2.30 2.42 120.00 1.95 a T A21 1.10 1.48 1.85 2.02 2.16 96.36 1.72 b T A22 1.10 1.48 1.92 2.11 2.18 98.18 1.75 b T A23 1.10 1.45 1.85 2.00 2.14 94.54 1.70 b Table 2: Effect of chemical preservatives on ph of strawberry juice Initial 20 40 60 80 % Decrease Mean ph value T A12 3.48 3.23 3.12 3.04 2.94 16.23 3.16 b T A13 3.48 3.31 3.23 3.21 3.17 8.90 3.28 a T A14 3.48 3.29 3.27 3.21 3.18 8.62 3.28 a T A15 3.48 3.30 3.27 3.22 3.19 8.33 3.29 a T A20 3.64 3.38 3.32 3.25 3.20 12.08 3.35 b T A21 3.64 3.45 3.43 3.40 3.36 7.69 3.45 a T A22 3.64 3.44 3.41 3.38 3.35 7.96 3.44 a T A23 3.64 3.46 3.43 3.40 3.37 7.41 3.46 a 220

Table 3: Effect of chemical preservatives on acidity (%) of strawberry juice Initial 20 40 60 80 % Increase Mean Acidity (%) content of juice T A12 1.68 2.49 2.95 3.54 3.82 127.38 2.89 a T A13 1.68 2.21 2.68 3.22 3.64 116.66 2.68 b T A14 1.68 2.30 2.88 3.18 3.45 105.35 2.69 b T A15 1.68 2.12 2.62 3.16 3.40 102.38 2.59 b T A20 1.10 1.85 2.12 2.30 2.42 120.00 1.95 a T A21 1.10 1.48 1.85 2.02 2.16 96.00 1.72 b T A22 1.10 1.48 1.92 2.11 2.18 98.18 1.75 b T A23 1.10 1.45 1.85 2.00 2.14 92.00 1.70 b Table 4: Effect of chemical preservatives on ascorbic acid of strawberry juice Initial 20 40 60 80 % Decrease Mean Ascorbic acid content mg/100 kg T A12 39.50 26.00 23.00 16.50 13.50 65.82 23.70b T A13 39.50 32.56 25.30 21.11 16.30 58.73 26.95a T A14 39.50 32.19 24.11 20.95 16.00 59.49 26.55a T A15 39.50 34.50 29.69 22.53 17.30 56.20 28.70a T A20 28.40 22.12 18.40 14.22 11.50 59.50 18.93b T A21 28.40 24.80 21.00 17.60 16.12 43.23 21.58a T A22 28.40 23.22 20.88 17.12 16.00 43.66 21.12a T A23 28.40 25.60 21.12 18.50 16.88 40.56 22.10a 221

Table 5: Effect of chemical preservatives on reducing sugar of strawberry juice Initial 20 40 60 80 % Dec/Inc Mean Reducing sugar T A12 5.80 3.20 3.09 2.98 1.93 66.72 3.40b T A13 5.80 6.12 6.34 6.48 6.60 13.79 6.26a T A14 5.80 6.12 6.36 6.50 6.62 14.13 6.28a T A15 5.80 6.10 6.32 6.46 6.56 13.10 6.24a T A20 23.58 21.40 16.23 15.84 15.07 36.08 18.42b T A21 23.58 26.00 27.98 29.32 30.12 27.73 27.40a T A22 23.58 26.02 28.00 29.34 30.14 27.82 27.42a T A23 23.58 25.92 27.84 29.12 29.88 26.71 27.27a Table 6: Effect of chemical preservatives on non-reducing sugar of strawberry juice Initial 20 40 60 80 % Dec/Inc Mean Reducing sugar T A12 1.42 0.68 0.56 0.48 0.42 70.42 0.71 b T A13 1.42 1.34 1.28 1.24 1.22 14.08 1.30 a T A14 1.42 1.34 1.26 1.22 1.20 15.49 1.28 a T A15 1.42 1.36 1.30 1.28 1.26 11.26 1.32 a T A20 5.04 3.48 2.64 1.26 0.48 90.47 2.58 b T A21 5.04 4.08 3.18 2.40 1.82 63.88 3.30 a T A22 5.04 4.06 3.16 2.38 1.80 64.28 3.28 a T A23 5.04 4.10 3.20 2.42 1.84 63.49 3.32 a 222

Table 7: Effect of chemical preservatives on overall sensory acceptability of strawberry juice Initial 20 40 60 80 % Decrease Mean Overall sensory acceptability score rate T A12 8.00 2.60 2.00 1.67 1.30 83.75 3.11 b T A13 8.00 5.30 3.00 2.30 2.00 81.25 4.02 a T A14 8.00 5.70 3.00 2.30 2.00 81.25 4.10 a T A15 8.00 5.70 3.00 2.67 2.00 81.25 4.14 a T A20 8.00 2.60 2.00 1.67 1.30 83.75 3.11 b T A21 8.00 6.30 3.67 3.00 2.67 75.00 4.59 a T A22 8.00 6.30 3.67 3.00 2.67 75.00 4.59 a T A23 8.00 6.30 4.00 3.00 2.67 75.00 4.66 a T A23 (7.41%) followed T A21 (7.69%). Similar results were recorded by Mehmood et al. (2008) during study of 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. Table 3 depicts that storage and treatments has a significant effect on the titratable acidity of strawberry juice. Maximum increase was observed in T A12 (127.38%) followed by T A20 (120.00%) while minimum increase was observed in T A23 (92.00%) followed by T A21 (96.00%). Similarly same 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. The results of Ayub and Khan (2001) are also 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. This increase may also be due to the breakdown of pectin into pectenic 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 shows that in vitamin C maximum decrease was observed in T A12 (65.82%) followed by T A20 (59.50%) while minimum percent decrease was observed in T A23 (40.56%) followed by T A21 (43.23%). The results are in agreement with the findings of Zeb et al. (2009) who worked on the preservation of grape juice with sodium benzoate and potassium sorbate, stored at room temperature for one month, they observed decrease in ascorbic acid content of grape juice. The results of Ayub and Khan (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 223

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. Our results showed that reducing sugars increased in all samples except in T A12 and T A20 (Table 5). Maximum increase was observed in T A22 (27.82%) followed by T A21 (27.73%) while minimum increase was observed in T A15 (13.10%) followed by T A13 (13.79%) while control samples (T A12 and T A20) showed decreasing trend during storage period. Mehmood et al. (2008) observed an increase in reducing sugar of apple juice preserved with chemical preservatives stored at ambient temperature for three months. Hussain et al. (2011) also reported increase in reducing sugar of apple and apricot blended juice, preserved with sodium benzoate at refrigeration temperature for three months. 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. Table 6 shows results of non reducing sugars of strawberry juice. Maximum decrease was observed in T A20 (90.47%) followed by T A12 (70.42%) while minimum decrease was observed in T A15 (11.26%) followed by T A13 (14.08%). Mehmood et al. (2008) observed decrease in non reducing sugar of apple juice preserved with chemical preservatives stored at ambient temperature for three months. 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 analysis The results of our data showed that storage period and treatments had a significant effect on overall sensory acceptability (Table 7). It was recorded that control samples, (T A12 and T A20), were spoiled soon after storage and resulted in producing off flavor, maximum loss in color, consistency while the treated samples retained comparatively better quality for longer period. 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. The results of Ayub and Khan (2001) are also 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 stored at room temperature for six months. CONCLUSION From the study it is concluded that sugar concentration and combination of preservatives play a positive role in extending the shelf life of strawberry juice. It was concluded from the research work that T A23=Strawberry juice (30.5 brix) with 0.05% sodium benzoate + 0.05% potassium sorbate and 0.1% citric acid followed by T A21=Strawberry juice (30.5 brix) with 0.1% sodium benzoate and 0.1% citric acid maintained better quality stored at ambient temperature for three months while control samples were rejected soon after storage. References 1. A.O.A.C. 2000. Official methods of analysis. Association of Official Analytical Chemist 13th edition. Washington, D.C. 2. Ayub, M., J. Ullah, A. Muhammad and A. Zeb. 2010. Evaluation of strawberry juice preserved with chemical preservatives at refrigeration temperature. Int. J. Nutr. and Metabolism. 2(2): 27-32. 3. Ayub, M and M. B. Khan. 2001. 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. Agr. 17(4): 629-632. 4. Gontared, N.R., C. Thibault and S. Guilbert, 1996. Influence of relative humidity and film composition on oxygen and carbon dioxide permeability of edible films. J. Agri. and Food Chem. 44: 1064-1069. 5. Hern andez, P.M., E. Almenar, M. J. Ocio and R. Gavara, 2006. Effect of calcium dips and chitosan coatings on postharvest life of strawberries (Fragaria x ananassa). Postharvest Bio. and Tech. 39: 247-253. 6. Hussain, I., A. Zeb and M. Ayub. 2011. Evaluation of Apple and Apricot Blend Juice Preserved with Sodium Benzoate at 224

Refrigeration Temperature. World J. of Agric. Sci. 7(2): 136-142. 7. Larmond, E. (1977). Method for sensory evaluation of food. Canada Dept. of Agr. Publ., 1286: 36-37. 8. Mehmood, Z., A. Zeb, M. Ayub, N. Bibi, A. Badshah and Ihsanullah. 2008. Effect of Pasteurization and Chemical preservatives on the quality and shelf stability of Apple Juice. Amer. J. Food Tech. 3(2): 147-153. 9. Nilugin, S.E. and T. Mahendran. 2010. Preparation of ready-to-serve (RTS) beverage from palmyrah (Borassus flabellifer L.) fruit pulp. J. Agri. Sci. 5(2): 234-237. 10. Sharma, S., V. K. Joshi and G. Abrol. 2009. An overview on strawberry [Frageria x ananassa (Weston) Duchesne ex Rozier] wine production technology, composition, maturation and quality evaluation. Natural product Radiance. 8(4): 356-365. 11. Steel, R.G.D. and J.H. Torrie. 1980. Principle and procedures of statistics. Mc Graw Hill Book Co. NY, U.S.A, 2nd ed, pp: 195-238. 12. Wisal, S., J. Ullah., A. Zeb and M. Z. Khan. 2013. Effect of refrigeration temperature, sugar concentrations and different chemical preservatives on the storage stability of strawberry juice. Int. J. of Eng. & Tech. 13(02):160-168. 13. Zeb, A, I. A. Khalil and M. Ayub. 2009 Grape juice preservation with benzoate and sorbate. J. Advances in Food Sci.31 (1):17-21. 225