Cereal Chem. 73 (6):751-755  |  VIEW ARTICLE

Nonwheat Grains and Products

Wet Milling of Grain Sorghum Using a Short Steeping Period.

Ping Yang (2,3) and Paul A. Seib (2,4). (1) Presented at the Annual Meeting of American Association of Cereal Chemists, San Antonio, TX, November 1995. Contribution no. 96-295-J of the Kansas Agricultural Experiment Station. (2) Graduate research assistant and professor, respectively, Department of Grain Science & Industry, Kansas State University, Manhattan, Kansas 66506-2201. (3) Present address: Department of Agricultural Engineering, University of Illinois, Champaign-Urbana, Urbana, IL 61801. (4) Corresponding author. Fax: 913/532-7010. Accepted August 12, 1996. Copyright 1996 by the American Association of Cereal Chemists, Inc. 

Commercial yellow grain sorghum was steeped in a vented container at 50-70ºC for 2-10 hr with 1.5 parts (by weight) of water containing initially 0.1-0.5% sulfur dioxide (SO(2)). During steeping, approximately 75% of the SO(2) was lost through the vent. When grain sorghum and dent corn were steeped at 58ºC with an initial concentration of 0.25% SO(2), steepwater uptake by grain sorghum was faster during the first 4 hr, but leveled off at 4% below that of corn after 10 hr. In addition, the steepwater of grain sorghum became 25% more acidic than that of corn after 2-10 hr. The optimum recovery of starch from grain sorghum steeped 4 hr was 51% at 58ºC with an initial concentration of 0.3% SO(2). Decortication of the grain sorghum produced 70% recovery of pericarp-free, broken kernels, which gave a somewhat reduced recovery of milled starch with only a slight improvement in brightness. The hot paste characteristics of the starches from two samples of yellow grain sorghums matched those of a commercial corn starch.