A Single Step High Temperature Hydrolysis of Wheat Starch

Abstract

Hydrolysis of native starch at 90°C by the α-amylase from Bacillus licheniformis and the α-glucosidase of Thermococcus hydrothermalis, an archaeum, has been investigated. The archaeal enzyme is optimally active at 110°C and pH 5.5. At 96°C, the half-life of the enzyme is 27 h in the presence of 10% (w/v) of starch. This α-glucosidase converts maltose into glucose and short oligosaccharides (G3 to G7) into glucose and maltose as the final products. Starch and long chain oligosaccharides are not hydrolysed by the enzyme. When the two enzymes were introduced simultaneously at the beginning of the hydrolysis a sugar syrup containing 74% (w/w) maltose and glucose was obtained after 24 h incubation. With 1 KNU α-amylase/g of starch and 3 U α-glucosidase/g of starch, the maximum rate of glucose production was 80 g × h−1 × 1−1.