Фізичні властивості колоїдно-пористих харчових систем

Abstract

Проведено комплексне дослідження реологічних властивостей колоїдно-пористих харчових систем з використанням Багатофункціонального вимірювального модульного приладу «МІГ-1.3». Зафіксовано функціональну залежність зміни релаксаційної сили та температурного поля в зразку під час осьової деформації стиснення у форматі реального часу. Отримано рівняння швидкості зміни деформаційної сили та швидкості поширення теплового поля. Отримані результати узгоджені з товарознавчими критеріями якості.The aim of the research is: obtaining a relaxation curve for colloid-porous food structures; recording the appearance of internal energy sources inside a sample during its deformation; researching the thermal field and the nature of its propagation; establishing relation between relaxation and thermophysical properties of colloid-porous food systems. As is known, deformation of food products induces formation of elastic forces that perform work to return an object to its original state. Thanks to the system of sensors of the "Rheology" module, it is possible to fix not only the state of loading and restoration of an object due to deformation, but also temperature change. Data recording takes place in real time and is displayed on the PC screen. As a result of the research, the following conclusions were drawn: the density of researched objects depends on porosity of the structure itself - the more air bubbles in the system, the smaller the density of a sample. Porosity of the system as well affects elastic properties of the samples. Restoration of the structure depends on elasticity of the reserched object, or rather its moisture. Wet marshmallows have good elasticity and weak relaxation properties. They get improved with 15% moisture loss of the original values. But if this index exceeds 20%, the researched object becomes brittle, visually dryness of the surface is detected. The results obtained are important for the development of new methods and tools for expertise of food products. Transportation of food products is related to deformation of objects. During deformation, the thermal field appears in a sample. The velocity and way of its distribution depends on spatial structure of a sample. Since within the study the food systems researched had colloid-porous structure, the air contained in pores plays a significant role and affects not only the circulation of air inside the pores themselves, but also the transfer of moisture and heat throughout the structure. During deformation, the heat-conduction coefficient increases, that is confirmed by histograms given in the article.