Production of Low-Alcohol Fruit Beverages through Fermentation of Pomegranate and Orange Juices with Kefir Grains

Fermentation of pomegranate juice as single or mixed substrate with orange juice, without addition of extra nutrients, using kefir grains is proposed. Sugar consumption and ethanol production were monitored during fermentation, while the formation of lactic acid and the survival of lactic acid bacteria were determined during storage at 4 degrees C for 4 weeks. The results showed that addition of orange juice improved the ability of kefir grains to ferment pomegranate juice, and increased the survival rates of lactic acid bacteria (LAB) contained in kefir grains during storage. Specifically, 75% cells survived (6.48 log cfu/ml) after 4 weeks of storage in the fermented mixed substrate (24% in plain pomegranate juice). Lactic acid formation was observed in all products, especially in the mixed substrate (1.3-1.9 g/l), indicating metabolic activity during storage. In all cases a low decrease of pH was observed. The results show the possibility to produce low-alcoholic nutritious fruit beverages with potential antioxidant (due to pomegranate constituents) and probiotic properties (due to the probiotic species present in kefir grains). In addition sensorial tests that were conducted showed the consumers acceptance for all the fermented juices.