Вестник МГТУ. 2020, Т. 23, № 3.

Вестник МГТУ. 2020. Т. 23, № 3. С. 224-236. DOI: 10.21443/1560-9278-2020-23-3-224-236 Introduction Modem meat processing production consists o f a variety o f technological processes and specialized equipment used for their implementation (Barbut, 2016; Bekhit, 2017; Cummins et al., 2016; Toldra, 2017), which is selected based on various technical and technological criteria, the main o f which is energy efficiency (Hamawand et al., 2017; Pathare et al., 2019). Without the involvement o f innovative technologies and appropriate means o f production, it is impossible to achieve progress in the food industry, in particular, such its sector as the meat and meat processing industry (Diachenko, 2017; Kovalenko et al., 2017; 2020). Along with mincing raw materials, filling casings and heat treatment, mixing o f ground meat is one o f the main technological operations o f sausage production, which largely determines the proper quality o f the finished product. Meat mixers, which mix minced muscle tissue with other pre-formulated ingredients, are among the most common types o f specialized meat processing equipment. Although the mixing o f raw materials is carried out simultaneously with its comminuting directly in cutters with a rotating bowl in the manufacture o f minced meat o f structureless sausages, the use o f flow cutters for comminuting, which are increasingly widespread, is also not complete without the use o f a ground meat mixer (Verbytskyi, 2016; Rogov et al., 2000). The quality o f ground meat - a food dispersed medium, including a solid, liquid and, partially, a gas phase - is determined by the dispersity and uniformity o f its structure, as well as the uniformity o f distribution o f components, that is, by the efficiency o f the mixing process using specialized equipment (Murashev et al., 2015). The physical essence o f the process o f mixing ground meat, in general, is down to the fact that when the working bodies o f the meat mixer rotate, there is a forced mutual convective diffusion - the mutual distribution of components in a multicomponent system. The mixing process is most efficiently fulfilled when the velocity gradients between the layers o f the mixed masses are the highest, and the velocity gradients over the working volume o f the mixer are the smallest. The larger the working volume o f the mixer, the more difficult it is to ensure the quality and speed of mixing. The temptation to intensify the process by increasing the speed of the working parts o f the mixer is fraught with the formation o f discontinuities in the density o f the processed mass under conditions of shear deformation, as well as an unjustified increase in power consumption (Vas’ukova et al., 2002). During the mechanical mixing o f raw meat by the working bodies o f the technological equipment, changes in muscle and adipose tissues are certain to take place. This contributes to an acceptable, in a technological sense, water-holding capacity of the resulting minced meat, the ability o f mutual adhesion o f fragments o f muscle and adipose tissue, this minced meat components (Sielaff et al., 2005). Ground meat being a dispersed medium includes solid, liquid and, partially, gas phase (Murashev et al., 2015). Ground meat used for manufacturing sausages, before its heat treatment, is a typical representative o f a body with a coagulation structure formed by the cohesion o f particles through interlayers o f a dispersion medium associated with them. Being a heterogeneous, dispersed phase o f the ground meat is represented by protein particles and aggregates, particles of fat, the smallest scraps o f muscle and adipose tissue, the continuous phase is an aqueous solution o f some muscle proteins, other organic compounds, as well as sodium chloride and other electrolytes. The proteins dissolved in the continuous phase impart stickiness and plasticity to the ground meat. As the liquid phase is being removed, it is accompanied by the appearance o f stronger bonds between particles, coagulation structures are formed from condensation structures, for example, ground meat for Mortadella type and raw smoked sausages (Verbytskyi et al., 2019). Shear deformation at a high mixing rate and density discontinuities in the mixed system does not contribute to the desired uniformity o f the mutual distribution o f phases, and at a high-speed mode, the power consumption increases sharply (Vas’ukova et al., 2002). It is extremely important to accurately select the shape o f the working blades o f the mixers and the elements o f their working bowls, since the above-mentioned features o f the process o f mixing viscous food media, in particular ground meat, lead to the fact that high-speed and energy-intensive mixing is by no means always high-quality mixing. However, in the total balance o f electricity consumption at a meat processing plant, 55 % are energy consumption o f refrigeration equipment, 25 % - various grinders, 11 % - ventilation equipment, 6 % - fillers, and only 3 % falls on all other technological equipment, including mixing devices1 (Verbytskyi et al., 2019; Kang et al., 2016). The uniformity o f mixing o f the entire volume o f the loaded product is one o f the main requirements that the design o f meat mixers must meet according to the national standard o f Ukraine DSTU 7511:2014 developed by the employees o f our scientific institution2, which regulates the manufacture o f these machines. In addition to the general norms for all food equipment, the standard establishes the following requirements directly related to the design o f meat mixers: - availability o f devices that protect service personnel from accidental contact with the working mixing body; 1 Becker, M. 2016. Energieeffizienz in der Kalte- und Klimatechnik durch adaquaten Einsatz von Automatesierungstechnik. Sindelfingen: Vortrag DKV-Bezirksverein Stuttgart, S. 1-57. 2 Installations and equipment for meat industry. Machines for mixing ground meats. Basic parameters, technical requirements and methods of testing: DSTU 7511:2014. ^ i v , State Enterprise "Ukrainian Research and Training Center of Standardization, Certification and Quality", 2014. 15 p. 225