Optimization of the process of herbal beverage fermentation by lactic bacteria starters

The distinctive properties of soy drinks are low cholesterol, high in protein and fiber, as well as important biologically active compounds. Fermentation increases the production of biologically active substances, and also improves the digestion of soy proteins by more than 40 %. The purpose of our study was to evaluate the adaptation of monospecific and complex starter cultures of lactic acid bacteria in the plant environment and the possibilities for optimizing this process, as well as to establish the effect of the fermentation process on the antioxidant properties of the probiotic drink. For fermentation, the following was used: monospecific concentrate of Lactobacillus acidophilus bacteria and bacterial starter “Acidophilus”, which includes strains: Lactococcus Lactis ssp. lactis, Lactococcus Lactis ssp. cremoris, Lactobacillus acidophilus, Lactobacillus helveticus. Fermentation was carried out at 32; 37 and 42 °C. As a result, a relationship was established between the temperature of the fermentation process and the titratable acidity of the drink: in a sample with a mono-species concentrate of the Lactobacillus acidophilus starter culture, the acidity for the first 14 hours of fermentation at a temperature of 32 °C reached a value of 13.9 degrees, which, in comparison with the complex starter culture at the same temperature mode lower by 9.9 degrees. The accumulation of lactic acid in samples with complex starter is more active; at a temperature of 37 °C, after 14 hours of fermentation, the content of lactic acid was 6.7 mg/100 ml. The optimum fermentation process in terms of temperature and duration for mono-species and complex starter cultures was 35.9 °C for 19.4 hours and 36.4 °C for 19.3 hours, respectively. The increase in AOA during fermentation ranged from 11.7 to 83.6 %. A more active adaptation of the complex starter is determined by the composition of microorganism strains with different temperature optimums, which makes such a starter more viable and resistant to thermal stress compared to mono-species.