Increase in the Activity of α-amylase Produced by <i>Aspergillus oryzae</i> in Dried Unripe Apple Pulp Culture on Addition of NaNO₃ and MgSO₄

Abstract

Unripe apples contain large quantities of starch and represent an unused organic resource. Starch hydrolysis in unripe apples may provide an effective method to utilize this resource as a food material. Aspergillus oryzae can be grown using unripe apples. However, the activity level of α-amylase produced by A. oryzae grown in dried unripe apple pulp remains unconfirmed. Therefore, we here examined various culture conditions that might increase this α-amylase activity. Our results suggested that for culturing A. oryzae in dried unripe apple pulp using the shaking culture method, the addition of NaNO 3 and MgSO 4 ·7H 2 O as nitrogen and magnesium and/or sulfur sources, respectively, was essential. Thus, α-amylase production by A. oryzae required high oxygen levels and additional nitrogen and magnesium and/or sulfur sources, both of which occur in low quantities in dried unripe apple pulp.