Sorghum β-Amylase Production: Relationship With Grain Cultivar, Steep Regime, Steep Liquor Composition and Kilning Temperature

Steep regime, nature of alkaline liquor, and kilning conditions were studied for their effects on sorghum malt β-amylase development in four Nigerian sorghum cultivars. Malt β-amylase activity was markedly (p < .001) influenced by all the four factors as well as their various interactions. Overall, malts from KSV 8 variety were the most β-amylolytic followed in sequence by those from Local Red (LR), SK 5912, and Local white (LW) respectively. The presence or absence of air rests in steep regimes was a significant (p < .001) determinant of sorghum β-amylase response to final warm steeping, steep liquor and kilning condition. The nature of the alkaline steep liquor was also a major determinant of the pattern of malt β-amylase response to the kilning condition. Steeping in Ca(OH)2 enhanced malt β-amylase activity at the higher temperature of kilning, while KOH produced the opposite effect. Ca(OH)2 enhancement of β-amylase development, at a kilning temperature of 50°C, was variety-dependent suggesting that different sorghum cultivars may employ different biosynthesis models for β-amylase synthesis. The regime-dependence of β-amylase response to kiln temperature suggests that this was an important modulator of sorghum germination physiology.