Effect of refrigerated storage on the physicochemical characteristics and viability of Lactobacillus plantarum in fermented watermelon juice with or without supplementation with inulin or fructooligosaccharide

Abstract

A non-dairy probiotic drink was produced through the fermentation of watermelon juice using Lactobacillus plantarum ATCC 8014. Watermelon juice was supplemented with or without inulin or fructooligosaccharides (FOS) and fermented for 6 hr at 37°C. The effect of two weeks of refrigerated storage at 4°C on the physicochemical characteristics and viability of L. plantarum were measured. The viability of L. plantarum with or without inulin or FOS supplementation was maintained at about 11 log CFU/mL until week 2 of refrigerated storage. The pH of fermented watermelon juice continued to decrease, whereas lactic acid concentration continued to increase until week 1 of storage. The supplementation of inulin or FOS increased the total soluble solids of the juice. There was notable change of color in all fermented watermelon juices measured using colorimeter. The concentration of glucose, fructose and citric acid measured using HPLC varied over the two weeks of storage. Practical applications Watermelon is widely consumed and accepted by consumers around the world. This paper presents an alternative to process this fruit by producing a non-dairy probiotic drink using watermelon juice as the substrate. Experimental results indicated that watermelon juice was a suitable substrate to produce probiotic drink and refrigeration for two weeks was able to maintain the quality of the juice. This drink may have the potential to be commercialized for consumers who would prefer a fruit-based probiotic drink.