Peculiarities of Steam Treatment of Food Plant Products and Simulation Thereof

Abstract

Methods of water steam treatment of disperse food raw materials at various pressures have become widely used in the processing industry. Humidity and temperature conditioning, drying and blanching are typical non-stationary processes progressing at a uniform or non-uniform (decreasing) rate. This article describes an analytical solution to the system of differential equations of joint heat and mass transfer outlining distribution of heat and moisture fields at the material heating stage. The following peculiarities of the food raw materials processing have been considered to set the appropriate boundary value problem: some of the processed food quality horticultural products (harvested potatoes to be dried, washed fruits or pretreated sunflower seeds prior to vegetable oil expression) were included with the group of products characterized by a tight-fitting subspherical fruit (seed) coat, which is why we consider them a single, homogenous, and isotropic particle with averaged thermophysical properties. The difference in temperatures of the heated air and the treated material results in condensation and formation of a liquid film on the surface of the objects, which is why heat is spontaneously transferred from the condensate film to the body primarily on account of heat conductivity and moisture distribution from the periphery to the center. The issues of storing agricultural plant products closely related to the discussed ones are no less important. Rational natural resource management globally acknowledged as the dominant economic development trend presumes the fullest possible use of processed human-consumed plant products. For instance, vegetable proteins prevail over meat ones in food patterns in most countries. In Japan, this ratio is 78.3/21.7, in Ukraine - 72.3/27.7, in the USA - 65.3/32.9, in the United Kingdom - 61.?/32.4, in Germany - 65.3/34.7, in France - 60/40, in Canada - 68.4/31.6, in China - 87.3/12.7, in Italy - 74.6/25.4. Adequate storage of the harvested plant products prepared for processing significantly contributes to the solution of this problem. Given the considerable amount of root vegetables, grain and seeds in food plant products, it is clear why foodstuff manufacturers show interest to conditions and modes of storage thereof. Modern warehouses used for these purposes are equipped with various means to ensure required hygrothermal modes and even to control composition of the environment within the units intended to store preserved bulk root vegetables, grain and seeds. That is why the discussed problems of analytical evaluation of storage conditions for various steam-treated bulk agricultural raw materials are of genuine interest.