Effect of Different Steeping Conditions on the Peroxidase Activities of Some Improved Sorghum Varieties

Abstract

In order to evaluate the impact of duration and the incorporation or  otherwise of air rest during steeping on the peroxidase activities of  sorghum grains, five improved varieties were studied. Steeping durations used ranged from 0 (raw grains) to 72 hours, in two formats: with air rest and without air rest. Results obtained showed that among the raw grains which were the control experiment, variety SK5912 gave the highest  peroxidase activity, followed by variety KSV 8 while variety CSRO2 had the least peroxidase activity. During steeping, we observed that in almost all cases, higher peroxidase activities were obtained with air rested sorghum grains than those without air rest. In terms of how the different varieties compared during steeping, we found that variety KSV 8 gave the highest peroxidase activity at both with and without air rest regimes in all the steeping periods used. Also, we observed that in all cases, the highest increase in peroxidase expression was obtained during the first 6 hours of steeping, shown by a steep rise of over 50% increase in activity. The other steeping times following the first 6 hours however showed just gradual  increases in peroxidase over the period of sorghum. The major significance of this result is that although increasing duration showed increased  peroxidase activities, such increases were less jumpy than those obtained during the first 6 hours. Therefore, long steeping times may not  necessarily be very beneficial, with the added benefit that costs associated with long steeping durations may be avoided.

Key words: Sorghum, cereals, peroxidases, enzymes, steeping, germination, air rest.