STUDYING PROTEIN PROFILE EFFECT ON CRYSTAL FORMATION IN MODEL DAIRY SYSTEMS WITH INTERMEDIATE MOISTURE CONTENT

The purpose of research is to study the influence of the protein profile of model dairy systems with intermediate moisture content on the process of crystal formation of milk sugar (lactose). Research objectives: selection of formulation components for compiling a protein profile and study of its influence on the process of formation and growth of lactose crystals in model systems during storage. The objects of research were model systems with targeted adjustment of pH values in each of them, imitating skimmed condensed milk with sugar, in which the complete or partial replacement of the protein phase with whey proteins was carried out through the use of dry whey protein concentrate, dry hydrolyzed whey protein (obtained in native or denaturing conditions), dry cheese whey. Studies of microstructural changes in consistency were carried out using the method for determining the size of lactose crystals according to GOST 29245-91. It has been established that a change in the protein profile towards an increase in the content of native and transformed whey proteins in model systems led to a slowdown in the process of lactose crystal formation. At the same time, hydrolyzed whey proteins had a higher degree of crystal growth restriction. The complete replacement of the protein phase with dry whey protein concentrate and dry cheese whey contributed to the intensive growth of crystals at their initial minimum average size (relative to other samples). However, after 14 days of storage, the average crystal size in this model system was comparable to the rest of the samples (including the control), except for the sample using hydrolyzed whey proteins. Regularities of the influence of the active acidity of the medium on the size of the crystals were also revealed. A decrease in pH from 6.2 to 5.6 leads to the formation of lactose crystals of a smaller average size by 1.9–3.3 times.