Functional fermented fruit juice production and characterization by using water kefir grains

In this study, production and characterization of probiotic beverages using water kefir grains with apple, orange, dragon and kiwifruit juices were aimed. The total phenolic and antioxidant capacity, phenolic profiles and physicochemical properties of the beverages were investigated to determine the impact of fermentation. The results showed that fermentation period significantly affects the lactic acid bacteria and yeast counts, organic acid content and phenolic profile of the produced beverages. The yeast, mesophilic lactic cocci and Lactobacillus count in beverages were changed within the range 5.59–8.57 log CFU/mL, 4.20–7.49 log CFU/mL and 4.36–7.37 log CFU/mL, respectively. The highest Lactobacillus spp. and mesophilic lactic cocci counts were determined in dragon juice (7.78 log CFU/mL) and kiwifruit juice (7.23 log CFU/mL) (48 h), respectively. Up to 21 phenolic compounds were identified in the juice samples. Chlorogenic acid and rutin were the major phenolic compounds detected in all fruit juices samples. Lactic acid level in all beverages increased during fermentation up to 9.03 g/L in fermented dragon juice. Furthermore, the ethyl alcohol concentration in beverages is within the regulatory limitations for non-alcoholic beverages. According to the finding, dragon, apple, orange and kiwifruit juices can be fermented with water kefir grains to produce non-dairy, functional, and probiotic beverages.