FACTORS INFLUENCING BETA-AMYLASE ACTIVITY IN SORGHUM MALT

An investigation into factors influencing beta-amylase activity in sor ghum malt confirmed that ungerminated sorghum grain exhibited essentia lly no beta-amylase activity. Malted sorghum had beta-amylase activity less than 25% of the level in barley malt. Neither reducing agents no r papain affected beta-amylase activity in sorghum, indicating that th e enzyme is not in a bound form, unlike in barley. Isoelectric focusin g indicated that sorghum beta-amylase comprises just one major and one minor isozyme of pI approximately 4.4-4.5, unlike the many isozymes a ll of higher pI in barley. However, like barley, sorghum beta-amylase was more temperature-labile than its alpha-amylase. Beta-amylase activ ity in sorghum malt was increased by germination time, high germinatio n moisture and over the germination temperature range investigated (24 -32-degrees-C), 24-degrees-C gave the highest activity. The beta-amyla se activity of sorghum malts was significantly correlated with malt di astatic power, despite the fact that alpha-amylase and not beta-amylas e is the predominant diastatic enzyme in sorghum malt.