The dissertation is devoted to the complex processing of milk into protein-berry concentrates, obtained by thermo acid coagulation of milk proteins with organic acids of berry coagulant. The use of this coagulant will increase the biological value and quality indicators of products.
The criteria for the selection of berry raw materials as a coagulant for thermo acid coagulation of milk proteins have been developed and the compliance of black currant berries with the requirements corresponding to regional availability, yield, industrial processing forms, sufficient levels of organic acids and vitamin C has been proved.
It has been substantiated that for the development of industrial technology which can be introduced into the production process and the provision of appropriate safety indicators of protein-berry concentrates, it is advisable to use as a coagulant specially processed black currant paste. This paste has fixed quality indicators and obtained in an industrial conditions using cavitation treatment.
The change of the yield and the moisture mass fraction of protein-berry concentrates on the amount of berry coagulant has been investigated. The influence of the berry coagulant of a different processing method, namely, the defrosted and specially processed berries, on the microbiological indicators of protein-berry concentrates has been determined. The feasibility of using blackcurrant paste as a coagulant, which has been specially processed and has the appropriate and fixed safety indicators, has been confirmed.
Scientifically-based technological parameters of obtaining protein-berry concentrates at the level are: temperature – (75±1) °С, duration (2±1) min. The amount of berry coagulant has been determined to effective carrying out the process of thermo-acid coagulation of milk proteins, which is (7±0.5) % (taking into account the limitations on the organoleptic indicators of the concentrate – the intensity of colour and taste). The influence of the amount of berry coagulant with different active acidity, and also the duration of thermo acid coagulation of milk proteins on the yield of protein-berry concentrates, their active acidity, moisture mass fraction, and water-retaining capacity have been investigated. Adequate regression equations have been obtained using experimental statistical modeling methods and graphic dependencies of the quality indicators of protein-berry concentrates from technological parameters of thermo acid coagulation have been constructed.
The effect of active acidity and mass fraction of organic acids in berry coagulant on the structural and mechanical characteristics of protein-berry concentrates has been studied, a scale for evaluating the consistency has been developed and recommendations for their use as a basis in the production of cottage cheese products have been summed up. The amount of bound and free moisture in protein-berry and milk-protein concentrates has been investigated by the method of differential thermal analysis. It respectively correspounds to 33.65 %, 68.32 % and 27.08 %, 71.26 %.
An increase in the total content of amino acids in protein-berry concentrates by 25.2 % compared with the control sample has been established. This is characterized by an increase in the degree of casein transition and the maximum amount of whey proteins into the concentrate, as a result of the organic acids action in blackcurrant paste during thermo acid coagulation. The content of 18 free and 16 bound amino acids, including nonessential and essential ones, has been identified, and the biological value of protein-berry concentrates has been determined. It is 6.74 % higher than this indicator for milk-protein concentrate.
The possibility of using coloured whey in technologies of fermented and non-fermented whey drinks has been proven by organoleptic, physicochemical parameters, colour and turbidity. The transition degree of polyphenolic compounds of berry coagulant into coloured whey and protein-berry concentrates, which is about 41.80 % and 52.26 % of their total amount, has been studied.
The technology of complex milk processing into protein-berry concentrates has been substantiated as the basis for cottage cheese products with high biological value.
Quality indicators of non-thermalized cottage cheese products based on protein-berry concentrates have been determined, their storage period is reasonable at a temperature of (4±2) °C – no longer than 72 hours.
The use of the maximum amount of coloured whey in the technology of a fermented drink based on skimmed milk has been substantiated. The level of replacement of the main raw material with coloured whey in mixtures for fermentation, taking into account the organoleptic restrictions, pH, according to the classical regimes at the level from 10 % to 20 % with the addition of (0.4±0.02) % Promilk 702 B has been determined.
