Rationale for the post-harvest processing of leaf mass of agricultural crops using microwave radiation

Abstract

Post-harvest processing of the leaf mass of various agricultural crops has general patterns. The peculiarity of the structure of the leaves is that the amount of water contained in the leaf blade and in the midrib is approximately the same, but the area of the evaporating surface of the midrib is 10–15 times less than the area of the evaporating surface of the leaf plate. Therefore, the difference in drying modes for these parts of the leaves justifies the need for different physical methods of influencing them. The aim of the research was to substantiate experimentally the general principles of moisture removal from the leaf mass of various agricultural crops using microwave radiation. Processing in the microwave field was carried out for 1,0; 1,5; 2,0; 2,5 minutes. The treated leaf layers were dried naturally. Leaves dried by convection under natural and artificial conditions, only without microwave treatment, served as a control sample. For the post-harvest processing of plantain leaves, a combined drying method is recommended, where in the first phase the leaves are treated with microwave radiation for 2,0–2,5 minutes, depending on the thickness of the leaf layer, and then in the second phase under natural conditions for 8 hours. Microwave – processing followed by convective drying in natural conditions is considered the most compromise method for drying beet tops leaves both in terms of drying time and in terms of the energy intensity of the process. On the basis on the results of the research, the application of the most rational processes of post-harvest processing of leaf mass of agricultural crops was substantiated, which consists in their processing by microwave radiation, followed by convective drying in a natural way.