Methodical aspects of producing biologically complete yogurt

One of the key trends in the food industry's development in Russia and globally is the expansion of the range of functional food products. This study aimed to investigate technological methods for producing functional yogurt with increased milk protein content. The research objectives included examining the effect of the chemical composition of the standardized mixture on yogurt consistency, substantiating the fat/protein ratio and the type of bacterial starter. Direct-inoculation dry starters were used: pure cultures of bifidobacteria, mesophilic, and thermophilic lactic acid bacteria. Standard and generally accepted chemical, physicochemical, and analytical methods were employed. The study examined the influence of two biologically complete components—milk fat and protein—on the moisture-retaining capacity of fermented milk curds. It was found that a decrease in the fat/protein ratio reduces the amount of whey released from the curd, and, accordingly, increases its moisture-retaining capacity. Methods for improving yogurt consistency, the roles of protein and fat in the formulation, and their impact on curd viscosity and density were explored. The addition of skim milk powder in quantities of 10.0% and 12.0% is sufficient in the yogurt composition. Higher protein values of 5.1–5.2% are not recommended due to the occurrence of a consistency defect – flouriness. Based on the study of the density of the curd, the chemical composition of the yogurt mixture is recommended: the mass fraction of fat is 2.5–6.0%, the mass fraction of dry matter is 10.0–12.0%. Combinations of DVS cultures are recommended for yogurt production: St-Body 3 + YF-L811 and St-Body 3 + ABT-5, and optimal fermentation temperatures are set at 41–42°C.