В работе приведены результаты исследования миграции зоны наименьшего прогревания (Slowest Heating Zone, далее SHZ) в упаковке при термической стерилизации мелкодисперсной гетерофазной пищевой системы для питания детей раннего возраста. Локализация SHZ является основным параметром, на основе которого производится разработка режимов термической стерилизации для пищевых систем с конвективным теплообменом. В качестве объекта исследования использовали сок яблочный с мякотью для детского питания отечественного производства, который представляет собой гетерофазную систему с жидкой дисперсионной средой и равномерно распределенной в ней высокодисперсной фазой в виде частиц мякоти с плотностью, близкой к плотности жидкой среды. Продукт был расфасован в стеклянные банки III-52-190. Прогрев проводили в термостате при температурах греющей среды 75, 80, 85, 90 и 95 °C, которые поддерживали и регистрировали автоматически, что обеспечивало равномерность температурного поля воды в термостате. Кривые прогрева снимали с помощью термопары, рабочий спай которой размещался по оси банки на высоте 6, 12, 18, 24, 30, 36, 40, 42 и 48 мм от дна. В результате экспериментальных исследований процесса стерилизации установлено, что в подобной пищевой системе локализация SHZ и кинетика ее миграции аналогичны этим параметрам в гомофазных пищевых системах, но различаются важными особенностями, вызванными как наличием дисперсной фазы, так и различиями в теплофизических параметрах продуктов. Отмечено влияние обязательной для питания детей раннего возраста гомогенизации сока с мякотью на вязкость продукта из-за упорядоченности ориентации частиц мякоти, вызывающей миграцию SHZ при изменении температуры сока при нагреве и охлаждении. The paper presents the results of researches of Slowest Heating Zone (SHZ) migration in packaging during thermal sterilization of fine heterophasic food system for feeding young children. Localization of SHZ is the main parameter on the basis of which the development of thermal sterilization modes for food systems with convective heat exchange is made. As the object of the study, we used apple juice with pulp for baby food of domestic production, which is a heterophase system with a liquid dispersion medium and a highly dispersed phase uniformly distributed in it in the form of pulp particles with a density close to the density of the liquid medium. The product was packaged in glass jars III-52-190. Warming up was carried out in a thermostat at temperatures of the heating medium of 75, 80, 85, 90, and 95 °C, which were maintained and recorded automatically, which ensured the uniformity of the temperature field of water in the thermostat. The heating curves were recorded using a thermocouple, the working junction of which was located along the can axis at heights of 6, 12, 18, 24, 30, 36, 40, 42, and 48 mm from the bottom. As a result of experimental studies of the sterilization process, it was found that in such a food system, the localization of SHZ and the kinetics of its migration are similar to these parameters in homophase food systems, but differ in important features caused by both the presence of a dispersed phase and differences in the thermophysical parameters of products. The effect of homogenization of juice with pulp, obligatory for feeding young children, on the viscosity of the product due to the regularity of the orientation of pulp particles, which causes migration of SHZ when the temperature of the juice changes during heating and cooling, has been noted.

When developing modes of food products thermal sterilization, it is necessary to determine the conditions for microorganisms test cultures and their spores guaranteed death in the least heating zone. The location of this zone is a critical parameter in thermal processes. At present, there are conflicting ideas about the localization and possible migration of the zone of least heating in the process of thermal sterilization of products with convective heat transfer. The kinetics of localization of the zone of least heating in the medium volume with convective heat transfer during heat treatment in conjunction with rheological properties was studied in the work. The clarified apple juice for baby food of domestic production was used as the object of study. The probe was placed so that the thermocouple was located on the vertical axis of the can at a geometric height of 3, 6, 9, 12, 18 and 24 mm. At each height value of the thermocouple, the jar with the sample was thermostated for 20 minutes, and then quickly cooled for 10 minutes. Heating was carried out at a thermostat temperature of 75, 80, 85, 90, and 95°C. The dynamics of rheological properties under isothermal conditions at temperatures of 30, 35, 40, 45, 50, 55, and 60°C and a range of shear rates from 0 to 700 s – 1 were also studied in the samples. As a result of the studies carried out, the presence of the migration of the zone of least heating during the heat treatment of single-phase media with convective heat transfer was determined experimentally, its kinetics was studied, the non-linear and reversible nature of the migration of the zone of least heating was established. The mechanism of the process of migration of the zone of least heating was proposed taking into account the dynamics of the rheology of the heated medium and the convective flows interaction.