Vacuum drying of apple, pear and raspberry varieties growing in the southern regions of the Republic of Kazakhstan

The article develops a methodology for conducting experimental studies on vacuum drying of varieties of apples, pears and raspberries growing in the southern regions of the Republic of Kazakhstan. Experimental studies and analysis of the influence of regime parameters on the drying process of selected products have been carried out, depending on the height of the layer of the dried material, the degree of grinding of raw materials, the degree of heating of the dried material and the pressure of the medium in the evacuated chamber.The analysis of the obtained drying curves for apples, pears and raspberries, in the initial state having a liquid paste-like mass, at the pressure in the vacuum chamber of 0.008 MPa, the loading height of 3, 4 and 5 mm, the degree of heating of the dried material - about 40 ° C, previously selected for research, shows that they have a similar character - all drying curves have quite clearly defined segments: the period of establishing regime parameters or the period of the beginning of drying, the period of constant drying rate and the period of decreasing drying rate.The results of experimental studies are generalized and based on them, equations describing the dynamics of moisture evaporation from the surface of products in the form of fourth-degree polynomial equations are obtained.