A new functional kefir fermented beverage obtained from fruit and vegetable juice: Development and characterization

A juice containing a mixture of fruits and vegetables (70% apple, 9% strawberry, 12% carrot and beet 9%) was evaluated as a potential substrate for the production of a novel probiotic beverage made with kefir grains. The effects of the kefir grains amount (1–4%, w/v) and fermentation time (12, 24 and 48 h) on the beverage composition, sensory qualities and colour were investigated. The results indicated that the amount of kefir grains have a significant effect on the content of the organic acids (lactic, acetic, citric, succinic, and malic acid), CO2 production, acidity, and viscosity and colour parameters (lightness (L*), hue (hab) and Chroma (C*ab)). Fermentation time also significantly affected all the parameters analyzed in the samples. The most suitable conditions to achieve the highest overall acceptability for the fermented beverage based on a mix of fruits and vegetable juice was: 2% (w/v) kefir inoculum during 24 h of fermentation time.