Slowest heating zone migration for heterophase model food system when sterilized

The aim of research is to study the dependence of the dynamics of SHZ migration in the process of sterilization of heterophase model FS in a dispersed phase that is not involved in the convection flow on the viscosity of the dispersion medium. The results of the study of the migration of the Slowest Heating Zone (hereinafter SHZ) of a heterophase model food system (hereinafter FS) in packaging during thermal sterilization with a solid dispersed phase and two versions of a dispersion medium of different viscosity are presented. Localization of SHZ in the package with the product is the main parameter on the basis of which the development and validation of thermal sterilization modes for food systems with convective heat exchange is carried out. Model FS was used as the object of research, in which the dispersed phase was represented by plastic balls 8 mm in diameter. A low-viscosity dispersion medium is a filling of green peas (1.5 % aqueous solution of NaCl and sucrose). Standard compote syrup - 11 % aqueous solution of sucrose, having a viscosity 1.6 times higher than that of the filling, was investigated as a medium viscosity dispersion medium. FS was packaged in glass jars (type III-52-190). Warming up was carried out in a water thermostat under isothermal conditions at water temperatures of 75; 80; 85; 90; 95 °C with an error of no more than ± 0.1 °C. Thermograms in the studied zones of the model FS were recorded using an MK thermocouple, the working junction of which was located along the can axis at a height of 3; 6; nine; 12; 15 and 18 mm from the bottom. As a result of experimental studies of the sterilization process, the presence of SHZ migration in the heating phase of the model FS and the dependence of the SHZ localization dynamics on the thermophysical properties of the dispersed phase particles and the rheological parameters of the dispersion medium have been established. The expediency of using the factor of heat treatment duration necessary to achieve reference temperature values to establish the sterilization mode is substantiated when determining the localization of the SHZ zone in heterophase FS with a dispersed phase that is not entrained by convective flows, as well as a decrease in the severity of SHZ migration with an increase in the viscosity of the dispersion medium.