EFFECT OF REFRIGERATION STORAGE ON THE GELATION QUALITY OF FERMENTED SOYMILK USING EXOPOLYSACCHARIDE PRODUCING LACTOBACILLUS PLANTARUM JCM 1149 ISOLATED FROM TAMARIND FRUIT
Keywords:
Exopolysaccharide, Fermented soy milk, Lactic acid bacteria, Refrigeration, storage.Abstract
Lactic acid bacteria fermentation is a reliable means of prolonging shelf life. This study was aimed at assessing the effect of refrigeration storage on the gelation quality of fermented soy milk using exopolysaccharide (EPS) producing Lactobacillus plantarum JCM 1149 isolated from Tamarind fruit. Soybean seeds milk was produced by extraction and pasteurized at 76oC for 30 minutes. Soymilk was divided into two portion, both portions were inoculated with 0.5mL (23.7×102 CFU/g) inoculum and incubated for 24 hours. One portion was fermented under optimal conditions (sample T) and the other portion was fermented at 37- 38oC without treatment (sample C). Fermented soy milk was stirred, packaged and refrigerated at 4oC. The viscosity, water holding capacity (WHC), pH, syneresis, microbial and proximate composition were evaluated using standard methods. The viscosity of sample T increases 1468.3 mpa.s on day 3 than the increase in sample C 1351.6 mpa.s on day 15. The WHC in sample T increases and decrease on day3 and day 15. Sample T had high WHC of 79.1% than sample C 32.2%. The bacterial count of sample C was significantly (p≤0.05) high on day 6 (12.70×102 CFU/mL) and decreases (9.30×102 CFU/mL) on day 15. Sample T had a bacterial count (7.60 ×102 CFU/mL) on day 0. Sample C and T had no coliform or fungal count. Sample T had high moisture content of 62.79% - 80.62%. Sample C and T had no significant difference in ash, crude protein and lipid content (3.47±0.09- 3.73±0.01), (3.02±0.00- 4.75±0.00) and (4.46±0.04- 4.51±0.01). The nitrogen free extract in sample T was high 3.47% than sample C 1.69% on day 9. Sample T had high energy content 53.46 kCal than sample C 41.31 kCal. The pH of sample C and T increases on day 6 (7.3 and 7.8) and decreases (5.6 and 6.2). However, sample C had high syneresis of 66.7% than sample T 49.04% on day 15. The EPS content of the fermented soy milk is attributed to the gelation quality of the product and assist in maintaining some yoghurt qualities. Bacteria activity is slowed down during refrigeration thus reducing spoilage and improving the shelf life of fermented soy milk.
