Solid-state fermentation (SSF) was carried out to produce α-amylase from Aspergillus oryzae using spent brewing grains (SBG) as substrate. The extracted enzyme was subjected to partial purification by ammonium sulphate fractionation. Maximum specific activity was obtained at 70% fraction. It was optimally active at pH 5 and 50°C by using 1% starch as substrate concentration. The partially purified α-amylase loses activity rapidly above 50°C but was retained in the presence of Ca2+ at an optimum temperature of 60°C.Improved Nigerian sorghum cultivars were malted and their brewing qualities evaluated. Their percentage protein and moisture content decreased with increase in days of germination. Statistical analysis showed a significant difference at (P-value <0.05) in theiramyloytic activity of the cultivars from first to the fifth day of germination. Mashing results obtained from the second temperature programmed mashing regime used with partially purified enzyme from Aspergillus oryzeaand calcium ion addition produced more reducing sugars, improved wort color, reduced viscosity and dextrin compared to that of first temperature programmed mashing and the single decoction regime with enzyme in the absences of calcium ion. Showing that the brewing spent grains can served as a good sources of hydrolysing enzyme, of which the presence of Ca2+ultimately stabilize and enhance its activity during mashing to produce improved results during brewing operations.
