DETERMINATION OF OPTIMAL MODES OF HYDROTHERMAL TREATMENT OF SORGHUM GRAIN

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Abstract

Two methods of sorghum hydrothermal treatment (HTT) with intensive grain moistening were studied. Intensification of grain moistening was carried out: in the first method - by steaming, in the second method - by moistening under vacuum with subsequent resting. The final stage in both methods of HTT was drying of grain in a fluidised bed. Search for optimal modes of HTT was carried out with the help of mathematical methods of planning experiments. The plan of the full factor experiment FFE 2³ was taken as a basis. When processing primary data and optimising the HTT process, as well as when building mathematical models, the programs ‘Stat Soft Statistica 13.3.7.704.19’ and ‘Microsoft Excel’ were used. In the method of HTT with stea­ming of sorghum grain as variable factors in the search for optimal conditions of the process were chosen: pressure of saturated water vapour; temperature of the drying agent; moisture of grain after drying. Duration of steaming was stabilised at the level of 4 min. In the method of HTT with moistening of grain under vacuum the following factors were changed at two levels: the degree of air rarefaction in the working chamber of the unit; temperature of the drying agent; moisture of grain after drying. Sorghum grain was moistened up to moisture (21,0±0,5) %, after moistening it was rested for 6 hours. The sorghum grain HTT process outputs were as follows: polished kernel yield; peeling coefficient; kernel integrity coefficient, kernel milling degree index. Programs of sorghum grain HTT process optimisation were calculated according to the Box-Wilson method with conside­ration of inter-factor interactions. Following the implementation of optimisation programmes and analysis of the obtained data, the optimal regimes of sorghum HTT with steaming and sorghum HTT with grain moistening under vacuum were determined