Physicomechanical and drying properties of soybean seeds under low-temperature convective drying

The peculiarity of the soybean drying process is that it slowly releases moisture, making it easily damaged by mechanical movements. The soybean shell dries faster, with the surface quickly dehydrating, while the central part remains moist. Soybeans must be dried so that the rate of moisture evaporation from the surface of the grain does not exceed the rate of moisture movement from the centre of the grain to its surface. Soybeans contain more protein and fat compared to grains of other crops. The large amount of protein in soybeans creates favourable conditions for the development of mould fungi. Additionally, soybeans are highly hygroscopic. Therefore, it is relevant to conduct a study of the characteristics of soybean seeds. The primary objective is to optimize the low-temperature convective drying process of soybean seeds by analyzing their physicomechanical and thermophysical properties, as well as evaluating the impact of drying temperature on seed germination and quality. In particular, an analysis of physico-mechanical, thermophysical, heat and mass transfer, kinetic, and biochemical characteristics was carried out. In the article, alongside a review of the literature concerning the properties of soybean seeds by various authors, original research has also been conducted. These properties depend on the action of a complex of factors, including the temperature and humidity of the heat carrier, seed humidity, and other variables. Knowledge of these properties enables the drying process to be carried out effectively and to be intensified. The properties presented, based on both the findings of other authors and the author's research, provide an opportunity for a comprehensive assessment of these characteristics. The original research can be divided into three stages, aimed at determining the following properties of soybean seeds as a drying object: physico-mechanical, thermophysical, and heat and mass transfer properties. The heat and mass transfer characteristics are calculated based on physico-mechanical, thermophysical, and experimental studies of drying soybean seeds. Drying of soybean seeds is conducted under low-temperature conditions to preserve the quality characteristics of the material. Increasing the temperature from 40 to 60°C intensifies the drying process 2.125 times. The resulting soybean seeds exhibit a germination rate of 90–96%, which decreases with increasing temperature.