Effect of heat treatment of sorghum grains on storage stability of flour

Sorghum flour is susceptible to rancidity and develops off-flavor within a short duration when stored. Heat treatment on the development of rancidity after long-term storage of flour was studied. Heat treatment varying in severity was applied to the whole grains of different varieties of sorghum viz., CSH-9, CSH-5, M35-1 and a local variety varying in their morphological features. A trend was seen that when the thermal duration was for a shorter time, the shorter was the storage duration in certain varieties. Exposure of grains to moist heat for 15 min retarded hydrolytic rancidity significantly (p < 0.05) in CSH-5 until 6 months of storage and in the remaining varieties until 8 months of storage. Heat application for 15 min retarded the development of rancidity irrespective of the morphological variations and the oil content. Lipase activity varied among the varieties with CSH-5 recording higher activity when compared to the other varieties. No major differences in the physicochemical properties were observed in flours from 15 min heat-processed grains when compared to flours from unprocessed grains. (C) 2011 Elsevier Ltd. All rights reserved.