Fermentation conditions of walnut milk beverage inoculated with kefir grains

The aim of the present study was to evaluate the use of kefir grains as inoculum for the preparation of walnut milk beverage. The results showed that the single factor effect of fermentation time, fermentation temperature and sucrose concentration on walnut milk beverage fermentation was very significant (P = 0.01), and the single factor effect of inoculum size was significant (P = 0.05). The suggested optimum fermentation conditions are the following: fermentation temperature of 30 °C, fermentation time of 12 h, inoculum size of 3 g of kefir grains (wet weight) and sucrose concentration of 8 g/100 mL. Under the optimum fermentation conditions, the sensory evaluation score of the beverage reached its maximum value of 88, and the pH and titratable acidity of the beverage were respectively 4.16 and 72 °T. The viable cell counts of lactococci, lactobacilli and yeast surviving in the beverage were 8.2 × 107, 1.1 × 108 and 1.0 × 106 CFU/mL respectively.