Abstract: In order to select a suitable mixed culture of probiotics for cloudy apple juice fermentation, 10 strains of common probiotics were screened based on their acid and bile tolerance and fermentation performance. The antagonism between the selected strains was evaluated and the mixing ratio of these strains was determined. Furthermore, we modelled the kinetics of biomass growth, metabolite production and substrate consumption. The kinetic parameters of the models developed were determined and verified. The results showed that: 1) a mixture of Lactobacillus acidophilus 6005, Lactobacillus plantarum 21805, and Lactobacillus fermentum 21828 was found to be the most suitable for the fermentation of apple juice at a ratio of 1:1:1 as determined based on sensory evaluation and viable cell counts, and the fermented apple juice had the best flavor and mouthfeel as well as the highest viable cell counts; and 2) the errors between the theoretical values from all these kinetic models and the experimental data were less than 10%, suggesting excellent goodness of fit. Hence, the kinetic models could predict the dynamic changes during the mixed culture fermentation of cloudy apple juice.

Key words: cloudy apple juice, probiotics, mixed culture fermentation, kinetics