MOISTURE EQUILIBRIUM OF SLICED BEETROOT AS AN AGROENGINEERING ANALYSIS PARAMETER

To make the agroengineering analysis of the drying process of sliced beets, it is necessary to know its moisture equilibrium. Due to the lack of the reference data for elevated temperatures at which drying of this material is carried out, the isotherms of moisture desorption were obtained and analyzed by the experimental static (desiccator) method for sliced beetroot at temperatures of 30, 40 and 50°C. The authors used saturated solutions of various mineral salts to get specific values of the relative air humidity in desiccators. They found the relative air humidity indicators in the space above them according to the well-known diagram of A. Schneider. The obtained moisture desorption isotherms are S-shaped, typical for capillary-porous colloidal materials, and they correspond to the fourth type of sorption isotherms according to the Brunauer classification. For the convenience of engineering analysis, they are described by the Henderson equation, which can be used to determine the values of the equilibrium moisture content of a material at various values of relative humidity and temperature. The authors have found values of the constants for this equation. A statistical assessment of the approximation reliability of the experimental data made by the Henderson equation has shown a satisfactory compliance of this equation with the experimental data. Since beetroot samples with high (natural) humidity were placed in desiccators when removing the equilibrium, the obtained isotherms are of the desorption type. They are exactly the type required to analyze the material drying process. The research results are applicable for analyzing the drying process for slicing beetroot and organizing the storage process.

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