Fractional composition of grain sorghum (Sorghum bicolor) after wet-peeling in a centrifugal pump

Use of a centrifugal pump to peel and facilitate separation of grain sorghum kernels into three fractions was investigated. Special emphasis was given to separating fractions to achieve a high concentration of wax in one fraction and a high concentration of starch in another. Trials were conducted to determine the effects of both soak time and recirculation time on wet-peeling. After peeling, three fractions, peeled kernel, bran, and suspended solids, were collected. Together, the bran and suspended solids fractions contained 12.7% of the initial total dry solids, 90% of initial wax, and 8.1% of the initial starch. Peeled kernel fraction accounted for 84% of the initial dry material, which contained 94% of the initial starch with 8.5% of the initial wax. Circulation through the pump for 5 min resulted in over 90% of the wax being concentrated in bran and suspended solids fractions, and over 90% of the starch was recovered in peeled kernel fractions. Soaking for 10 min versus no soaking increased the starch available in the peeled kernel fraction to 94%. Circulation time through the centrifugal pump had a more significant effect on separation of constituents than the soak periods studied.