Low quality sweet potatoes roots were used as a carbon source to produce
extracellular alpha-amylase by Asperigiffus arrzae in shake flask cultures. Peak
alpha - amylase production was obtained by local strain of Aspergillus oryzae on
sweet potatoes filtrate medium amended with saHs solutions and sodium nitrate, pH
6.0 after incubation at 3Q·C for 5 days. The optimum temperature and pH of the
enzyme activity was 50"C and 5.6, respectively. The optimum time for enzyme
actiVity, using starch buffered 0.5%, was 1h at optimum pH 5.6 and optimum
temperature 50·C. The produced enzyme is stable at temperatures below 50·C, while
the enzyme lost 13.1, 24.5,46.8 and 57.2% of its original activity after exposure at 55,
60,65 and 75·C for 1h., respectively.