EFFECTS OF AIR REST PERIODS ON MALTING SORGHUM RESPONSE TO FINAL WARM WATER STEEP

The effects of various lengths of air rests on response of malting sorghum main root length, malting loss, diastatic activity, alpha- and beta-amyloytic activity and extract to final warm water steep at 40 degrees C was investigated. Grains were steeped in distilled water for a total of 48 h at 30 degrees C with a 6 h final warm water steep under four different cycles incorporating 1, 2, 3 or 4 h air rest periods. All malt quality properties evaluated were significantly affected by the length of air rest, the cultivar and their pair-wise interactions. Main rootlet length and malting loss reduced progressively as the length of air rest increased. Reducing power, alpha- and beta-amylolytic activity and extract generally increased as the length of air rest was increased for both sorghum cultivars ICSV 400 and KSV 8 examined. The steep cycle incorporating 3 h length of air rest was found by experiment to give the optimum levels of malt quality indices analysed while at the same time causing considerable reduction in average main rootlet length and total malting loss for both grain cultivars.