DEFINITION OF QUALITY INDICATORS OF DAIRY-PROTEIN CONCENTRATES IN THE STORAGE PROCESS

Abstract

The aim of this article is to investigate changes in the structure, color and microbiological parameters of milk-protein concentrates (MPC) made of buttermilk with the use of cranberry or viburnum purees in the process of storage. Necessary results were obtained after analyzing phase transitions, changes in color-parametric and microbiological characteristics of the studied products. Low-temperature phase transitions and their influence on the structure of MPC were investigated using the method of differential scanning calorimetry. This method was used to obtain information on the change in the temperature function, depending on the change in heat absorption typical for melting, crystallization, or glass transition of components of MPC. The obtained dependences indicated an increase of heat absorption leaps of concentrates in relation to control, which indicates an increase in the amount of bound moisture and, accordingly, a decrease in significant changes in the structure of concentrates in the process of storage. In addition, it was found that rational was the rapid freezing of MPC at a temperature of –20...–30 ° C. The CIE XYZ and CIELab methods were used to evaluate the change in the color-parametric characteristics of MPC. According to the data obtained, red or yellow spectral tone dominates for the samples, but with an increase in the storage time, one can see a significant shift in the color of both concentrates towards the yellow color. It is also established that with increasing of storage time there is a gradual darkening of MPC. It was defined, that rational was the shelf life of up to 30 days from the time of studied products making. It was also determined that with the use of deep freezing of the MPC, the storage time has no significant effect on the development of the microflora.