The effect of the vacuum drying process on the appearance of cracks in the seeds

Abstract

Annotation Purpose. Theoretically analyze the effect of vacuum drying parameters on the appearance of cracks in seeds. Methods. The theoretical positions of drying capillary-porous bodies and physicochemical foundations of the food industry are used. The analysis of mathematical dependencies was performed based on the methods of analytical algebra and mathematical analysis. Results. Based on the analysis of the movement of moisture during drying of a single seed, it was found that drying without cracks on the surface of the seed is possible when the rates of moisture diffusion inside the seed and evaporation of moisture from the surface layers are equal. The analytical dependence, which implements this condition and obtained using the differential equation of diffusion, made it possible to obtain the dependence of the vacuum in the drying chamber on the temperature of seed heating. This dependence shows that it is possible to realize the condition of drying without cracks only by changing the vacuum in the drying chamber in an inverse exponential manner. Heating seeds reduces the vacuum in the drying chamber, at which drying begins. Conclusions. An analysis of the operational parameters of vacuum drying of seeds revealed that for guaranteed drying of seeds without cracks, it is necessary that the rate of diffusion of moisture inside the seed be equal to the rate of evaporation of moisture from the surface layers. Technically, this is achieved by varying the vacuum in the drying chamber in time by the inverse exponent, using data from the sensor for heating the seeds. An increase in the heating temperature of the seeds requires a proportional decrease in the initial vacuum in the drying chamber. Keywords: seeds, vacuum in the drying chamber, heating temperature, evaporation rate, vacuum drying, diffusion, equivalent ball of seed.