Changes in the Activities of Alpha and Gluco-amylases during Malting of Some Improved Nigerian Sorghum Varieties

Abstract

In this study changes in the alpha and glucoamylase activities of four different improved sorghum varieties were monitored over a 96-hour malting time to determine how the expression of the enzymes were affected by malting. Preliminary tests showed that SK5912 had the highest weight of 40 g/1000 grains and lowest malting loss of about 13%, while KSV 8 followed a weight of 36 g/1000 grains and the most malting loss of 22.6%. Enzyme results showed that the different sorghum varieties differed in their expression of the two of them across different malting regimes. However, all the varieties showed much higher expressions of glucoamylase than α-amylase at all the malting regime. Glucoamylase consistently showed its highest activities of over 71 U/ml across the four sorghum varieties after the first day of germination with variety SRNA giving the highest value slightly above 72 U/ml. The least glucoamylase activities were also given consistently across the four varieties by the unmalted raw grain. The highest α-amylase activities were generally shown across the four varieties after the third day of germination, with variety KSV 8 showing the highest value of about 14 U/ml. The control also gave the least α-amylase activities across all varieties with KSV8 giving the least. Considering the many important and multi-faceted roles that amylases are nowadays known to perform, the study of their expression dynamics in different plants and processes, one of which we report here, could help further the understanding of their characteristics and thus facilitate their maximal utilization.