Characteristics of the heterophase food system thermal sterilization process on the example of apple juice with pulp

The paper presents the results of a study of the influence of thermostating regimes of a heterophase food system on cumulative lethality and rheological properties. Heterophase system FS - apple juice with pulp (RSV content - 11 %). The choice of FS is due to the maximum approximation of its properties to the properties of real FS from heterophase raw materials. To test the sterilization modes, FS was packed in glass jars with a capacity of 190 ml. The thermocouple was placed along the central axis of the jar at a geometric height of 18 mm. FS heating was carried out in a water thermostat of the WCH-16 type under isothermal conditions with a temperature stabilization error of no more than ±0.1 °C and subsequent cooling in water. Thermostat temperature range is 75, 80, 85, 90 and 95 °C. The processed experimental data of studies of heterophase FS are distinguished by a large variability in the nature of heating at the initial stage, which lasts about 10 minutes. The resulting character of the accumulation of lethality F(τ) for the entire temperature range tst 75-95 °C on the graphs is similar and differs in the obtained values. The average lethality of the F cycle was 10.3-223.72 minutes. High variability of heating dynamics FS from t0 to t ≈ tst largely depends on pomological varieties and the region where apples are grown, the ratio of puree and juice with pulp and processing equipment (crushers, mashers, homogenizers). The results of studies of the rheological properties of heterophase FS showed that within the heating range from 30 to 60 °C, it has the properties of a non-Newtonian fluid - a medium with a pronounced nonlinear change in dynamic viscosity with increasing shear rate.