Application of the Mixture Design to Design the Formulation of Pure Cultures in Tibetan kefir

To obtain the optimization formulation of pure cultures in Tibetan kefir, the influence of the different mixtures of five strains in the pure cultures in Tibetan kefir on the flavor components in fermented milk was studied using the mixture design. The regression model on microorganism composition and main metabolites was established. The results suggested that the predictable production of lactate reached the maximum of 8.16 g L−1, while the most predictable production of diacetyl, ethanol, and CO2 were 77.23 mg L−1, 4259 mg L−1, and 2.12 g L−1, respectively. Based on these, the response values that satisfied all expectations were optimized, and the most excellent combination was Lactococcus lactis 27%, Leuconostoc mesenteroides 37%, Lactobacillus kefiri 11%, Lactobacillus casei 10%, and Kluyveromyces marxianus 15%. With the aid of analysis software (Design-expert 6.0.5), the formulation of pure cultures in Tibetan kefir can be optimized for several responses and the best formulation can be obtained.