Вестник МГТУ. 2020, Т. 23, № 3.

Шокина Ю. В. и др. Изучение реологических свойств гелей на основе бульона из хрящей ската. Objects and methods of the study The objects o f research were experimental samples o f fish broths based on the cartilage o f thomy skate prepared with the addition o f food gelatin o f industrial production according to GOST 11293-89 in concentrations from 0.54 to 5.0 %, as well as gels based on them; control samples are aqueous solutions o f gelatin concentrations from 0.5 to 5.0 % and gels based on them; rheological properties o f CSB are kinematic and dynamic viscosities; rheological properties o f gelatin gels based on CSB are gel strength, gel melting point and the indicators o f ultimate shear deformations o f gels. The objects o f research were experimental samples o f fish broths based on the cartilage o f thorny skate prepared with the addition o f food gelatin o f industrial production according to GOST 11293-89 in concentrations from 0.54 to 5.0 %, as well as gels based on them; control samples are aqueous solutions o f gelatin concentrations from 0.5 to 5.0 % and gels based on them; rheological properties o f CSB are kinematic and dynamic viscosities; rheological properties o f gelatin gels based on CSB are gel strength, gel melting point and the indicators o f ultimate shear deformations o f gels. The used research methods are the following: - organoleptic (evaluation o f prototypes at a scale developed by taking into account the weight coefficients o f indicators) according to GOST 7631-20134; - physical - density determination o f the broth in the ''Laktan 1-4" device by the developed technique, considering the coefficient o f correlation established by the calibration methods; - physical-chemical determination o f the mass fraction o f protein (P) and fat (F) on the "Laktan 1-4" device by the developed technique considering the coefficient o f correlation established by the calibration methods (GOST 7636-855); - determination o f kinematic viscosity using a viscometer according to GOST 10028-816; - determination o f dynamic viscosity o f broths by calculation; - determination o f gel strength via the Valenta device (Antipova et al., 2004); - determination o f the melting temperature o f the gel by determining the limit shear deformations on the rheometer "Physica MCR 302" with a measuring cone-plate cell with a fixed value o f the deformation amplitude and frequency (Panagos et al., 2014); - determination o f emulsifying capacity (EC) by centrifuging a mixture o f broth with sunflower oil in a calibrated test tube at a centrifuge speed o f 500 rpm, followed by determining the volume o f emulsified oil; - determination o f emulsion stability (ES) by heating a mixture o f broth with sunflower oil at a temperature o f 80 °C for 30 minutes, cooling with water for 15 minutes, and then centrifuging the mixture in a calibrated test tube to determine the volume o f the emulsified layer (Antipova et al., 2004). Results and discussions For the production o f semi-finished products o f natural fish culinary products, a technological scheme for preparing aspic from the cartilage o f the thorny skate, shown in Fig. 1, has been developed. The main stages o f processing fish raw materials in the proposed technological scheme correspond to the basic generally accepted technology for preparing fish aspic. An innovative stage is the primary treatment of thorny skate wings, which includes blanching, designed to reduce the mass fraction o f urea in the raw material as a result o f its thermal decomposition at temperatures above 60 °C (Shokina et al., 2014; Shchetinsky et al., 2012). New technological operations that distinguish the developed technology from the basic one are highlighted in Fig. 1 with a colored dotted line. The skate was cut up manually, and the fish's head, fins, wings, and tail fin were removed, as well as their insides. The wings o f the skate were thoroughly washed in running water, after which they were immersed in water with a temperature o f 96 to 98 °C for 1 minute. Then the blanched wings were cooled to a temperature no higher than 45 °C at a room temperature via air. The skin (waste) and meat (food production material) were separated from the cartilage, which was then sent to the preparation o f CSB. To prepare the broth, cartilage was filled with cold water in the ratio o f cartilage and water mass 1 : 1 and cooked at a low boil (at a temperature of 90 to 95 °C) for 1.5 hours with a single top-up o f water to the initial volume. Then the broth was cooled to a temperature no higher than 60 °C, filtered, degreased, added salt and spices according to the recipe, brought to a boil and boiled for 5 minutes. Part o f the broth was cooled to room temperature and used for soaking gelatin. Soaked gelatin in the amount set by the recipe (experimental scheme) was combined with the rest o f the broth, then 80 % acetic acid was added according to the recipe and dissolved when heated to a temperature o f 80 to 4 G O ST 7631-20 1 3 . F ish, n o n -fish objects and products from them . M eth od s o f sensory and p h y sical characteristics identification. M oscow , 2010. 5 G O ST 7636-85. F ish , m arine m am m als, invertebrates and pro d u cts o f th eir pro cessin g . M eth o d s o f analysis. M oscow , 2010. 6 G O ST 10028-81. G lass capillary viscosim eters. S pecifications. M oscow , 2005. 304