Вестник МГТУ, 2024, Т. 27, № 3.

Живлянцева Ю. В. и др. Использование белкового гидролизата из вторичного рыбного сырья. Test microorganisms were obtained from specialized collections: Staphylococcus aureus ATCC 25923 ROSENBLACH1884 ; Salmonella enteriditis No. 5765 (ex Kauffmann & Edvards 1952) le minor & Popov 1987. For the prepared culture media: control and test (containing a test sample of fish protein hydrolysate), coefficient of productivity of culture medium was calculated according to GOST ISO 11133-2016 "Microbiology of food products, animal feed and water. Preparation, production, storage and determination of the working characteristics of nutrient media". After cultivation on the studied culture media, biochemical signs during the identification of microorganisms were determined using test systems (Diagnostic kit No. 2, Scientific and Production Association "Microgen", Russia). Results A prototype of fish protein hydrolysate was obtained by enzymatic hydrolysis of cod musculoskeletal waste. As an enzyme preparation, we used protosubtilin G3X - a product of the activity of bacteria of the Bacillus subtilis strain (Sibbiopharm, Russia). The proteolytic activity of the enzyme is 560.77 ^mol TYR/g. One of the quality parameters of fish protein hydrolysate is the degree of hydrolysis determined in various ways. The most common indicator is the ratio of the mass fraction of amine nitrogen to the mass fraction of total nitrogen in the hydrolysate. The degree of hydrolysis of the obtained fish protein hydrolysate is 28.06 % (Куранова и др., 2016). According to the literature data the degree of hydrolysis of the most promising enzymes - bromelain and papain - is 23.74 %. In addition, the choice of the enzyme was due to its lower cost compared to other enzymes, for example, trypsin, pancreatin, pepsin, bromelain and papain, etc., which are used in the production of industrial fish protein hydrolysates. When optimizing the fermentation parameters, the dosage of the enzyme preparation was varied in relation to the mass of the hydrolyzed raw material (Xb %) and the duration of exposure (X2, hour) at the previously specified temperature of 45 °C. The numerical characteristic of the value of the achieved degree of hydrolysis (Y, %) was chosen as an optimized parameter. We used a rotatable composite plan (Живлянцева и др., 2018) for a two-factor experiment (Table 1). Table 1. Results of experimental data processing on optimization of the fermentation stage of hydrolysis of cod waste Таблица 1. Результаты обработки данных экспериментов по оптимизации стадии ферментации гидролиза отходов трески Parameter 1 2 3 4 5 6 7 8 9 Х 1 , % 0.6 0.6 1.5 1.5 1.05 1.69 0.41 1.05 1.05 Х2, hour 2 5 2 5 3.5 3.5 3.5 1.38 5.62 Y, % 23.5 23.9 26.5 27.0 27.5 27.6 22.8 24.3 27.6 As a result of processing experimental data the following equation describing the influence of the studied factors on the optimization option was received (Живлянцева и др., 2018) Y = ax1 + bx12 + cx2 + dx22 + ex23, (1) where Y - the value of the achieved degree of hydrolysis, %; x1- the dosage of enzyme preparation, %; x2- the duration of hydrolysis, hour; a, b, c, d, e - the regression coefficients: a = 17.08; b = -6.42; c = 14.14; d = -3.80; e = 0.32. Fisher's criterion for this equation is 80.84, it means that with the given confidence level (0.99), the regression equation reliably describes the change in the optimization parameter depending on the change in factors X 1 and X 2 . To find the optimal values of the factors X 1 and X 2 determining the optimal parameters of the hydrolysis process, we used the methods of mathematical processing (differentiation). The values of these optimal factors are as follows: Xi (concentration of the enzyme preparation) - 1.33 % by weight of raw materials; X2 (duration of the hydrolysis process) - 3 hours (Живлянцева и др., 2018). Considering the research carried out, an algorithm for obtaining a fish protein hydrolysate has been developed. For further research, we used a hydrolysate prepared according to the developed algorithm, considering the optimized fermentation conditions. The quality indicators of the prototype fish protein hydrolysate are presented in Table 2. Fish protein hydrolysate is an amorphous, light yellowish powder with a weak mushroom aroma. It has the ability to emulsify, foaming, when dissolved in water gives opalescent solutions, which confirms the preservation of the properties of the native protein in the product. Studies of the biological value of the product had found that the hydrolysate contained all protein amino acids, including essential ones, the minimum amount contains tryptophan (4.0 mg/g protein), the maximum amount contains hydroxyproline (150.6 mg/g protein) (Куранова и др., 2016). 296