Practical Approaches to the Control of Milk Fermentation with Kefir Grains

In the chapter, milk fermentation for kefir production is studied. The traditional kefir production process based on inoculating kefir grains into milk is considered. The quality and quantity of the produced kefir also depend on the dynamics of the fermentation process. The chapter presents the design and synthesis of the closed-loop control system in which changing the bioreactor’s temperature is used to control the time course of the concentration of dissolved CO2. In the chapter: (1) a nonlinear dynamic mathematical model of the fermentation process, which allows evaluating the influence of the bioreactor’s temperature on the dynamics of the fermentation process, is presented; (2) the design and synthesis of a conventional linear control system with constant parameters are carried out; (3) an adaptive control system that enables the tracking of the courses of the quantities of the fermentation process to the desired reference trajectories without the time-consuming preliminary identification of the parameters of the fermentation process model is developed. The numerical, experimental, and analytic outcomes of the study are presented.