Engineering properties of horse gram (Macrotyloma uniflorum) varieties as a function of moisture content and structure of grain.

Abstract

The study was conducted to determine the engineering properties of horse gram varieties namely GPM-6, PAYIUR-2, and BHK as a function of moisture content in range of 10-30%. The average length, width, thickness, geometric mean diameter, arithmetic mean diameter, thousand kernel weight, sphericity, porosity and angle of repose ranged from 5.43 to 6.53mm, 3.96 to 4.48mm, 2.21 to 2.99mm, 3.62 to 4.41mm, 3.86 to 4.64mm, 30.32 to 49.11g, 63.56 to 72.66%, 35.20 to 38.76% and 22.72° to 29.86° respectively as the moisture content of the grain increased from 10.08 to 29.98%. The bulk density and true density of the grain decreased from initial range of 810-901 to 734-801kgm-3 and 1250-1426 to 1168-1308kgm-3. The volume, porosity and terminal velocity of the grain increased linearly with increase in moisture content. The coefficient of friction also showed positive correlation for all surface materials, the highest increase was found for plywood in all varieties of horse gram seeds. Dehulling properties of the grain found to be significantly affected by the change in moisture content. The overall dehulling ranged from 53.44 to 61.21% for GPM-6 and 55.58 to 61.06% for PAYIUR-2 variety of horse gram. Textural properties of the grains were also found to be significantly affected by the change in moisture content from 10 to 30%. The data generated in this study will be highly useful in optimization of post-harvest processing operations as well as to design and develop related processing equipment for horse gram.