Optimization of production of the fermented milk beverage based on Tibetan kefir grains

In recent years we have seen interest in Tibetan kefir grains (TKG) for production of fermented milk beverages. The article presents the results of the work on expanding the range of fermented milk beverages based on TKG, studying the influence of fermentation conditions on quality characteristics of beverages and their shelf life. The possibility of their optimization is shown. Using the method of Central Composite Design (CCD), response functions were obtained in the form of 2nd-order polynomials, and the numerical values of the coefficient of these dependencies were calculated. The conditions of milk fermentation by Tibetan kefir grains were optimized. The numerical values of the influencing factors are: the dose of inoculate is (60 ±2) g per 100 ml of the milk, fermentation duration -(30±3) h; fermentation temperature - (35±4)°C. We also studied the effect of sea buckthorn, chokeberry and lingonberry juice additives on the quality of fermented milk drinks and their shelf life. Using the same method CCD we determined the functional dependencies of sensory indicators and shelf life of the beverage on the added amount of berry juice and sucrose. According to the results of the conducted studies, the recipe of a fermented milk beverage was modified. The optimal content of the components (per 100 ml of the drink) is: juice – (12±2) ml, sucrose - (10±1) g