Moiseeva L. Technology development of a low-lactose fermented milk product

The dissertation substantiated experimentally technological solutions to reduce the lactose content in milk raw materials to a level acceptable for consumption by the category of people intolerant of lactose. The rational parameters of the enzymatic hydrolysis of lactose by the preparation of neutral lactase in milk raw materials with an increased content of dry substances have been established. As part of the milk base for the production of fermented milk low-lactose products, the use of condensed demineralized whey or skimmed milk powder is justified. The effect of the species composition of the starter preparations and the initial composition of milk mixtures upon the carbohydrate composition of fermented milk curds with the hydrolyzed lactose was determined. It was shown that after fermentation with thermophilic cultures of Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus, the lactose content was less than 0.1 g / 100 g, the glucose and galactose content was 2.5... 3.5% each. An increase in the milk-clotting activity of starter preparations in a medium with hydrolyzed lactose was noted. At a temperature of 42 oC, the duration of fermentation of normalized mixtures with hydrolyzed lactose is 6,0 ± 0,5 h. It was found that in the presence of glucose and galactose, as the only source of carbohydrates, the production of exopolysaccharides decreases in comparison with the amount of exopolysaccharides synthesized on the corresponding media with non-hydrolyzed lactose. It has been confirmed that the use of demineralized whey in the composition of the milk base increases the content of essential amino acids and the water-holding capacity of fermented milk curds. The dependence of the parameters of the effective viscosity of fermented milk curds on their protein composition has been established. The effective viscosity of mixtures based on demineralized whey was lower compared to the viscosity of mixtures based on skimmed milk powder. The possibility of using rice flour as a consistency stabilizer has been substantiated, this causing no deterioration of the digestibility of the product and or its biological value. Microbiological studies of the products during storage confirmed a high content of viable cells of lactic acid bacteria for 15 days, which amounted to more than 10 8 CFU / g. The viability of microorganisms was better in fermented milk products with the demineralized whey. It has been established that due to an increase in the relative content of monosaccharides in milk mixtures, their sensorial organoleptic properties are improved after hydrolysis, which makes it possible to avoid the use of sugar in formulations, to increase the nutritional and dietary value of low-lactose fermented milk products. The products can be recommended for children aging from 2 years. The novelty of technological solutions is confirmed by the patent of Ukraine for an invention. The tested formulations, established technological parameters of technological processes and quality indicators of basic raw materials and target products have become a ground to develop the technology and regulatory documentation for the production of a low-lactose fermented milk product.