The role of Aspergillus flavus and Aspergillus niger in the hydrolysis of hazelnut fat

Abstract

Abstract Hydrolysis of hazelnut fat by moulds such as Aspergillus flavus and Aspergillus niger has been investigated. The activity of mould lipases was determined by measuring triacylglycerol (TAG), free fatty acid (FFA) and partial glyceride contents of hazelnut at different times in varying relative humidity (RH) levels and at 30 °C. TAG decomposition and FFA formation caused by A. flavus lipases started earlier than that caused by A. niger lipases and the results were not affected by r.h. FFA formation was higher using A. flavus lipases than A. niger lipases at 80 and 85% r.h. but not at 90% r.h. FFA levels increased with increasing r.h. and reached 62% after 28 days of storage at 90% r.h. using A. flavus lipases. An increase in the r.h. from 80 to 85% did not affect the TAG decomposition by A. niger lipases. FFA was 91% using A. niger lipases at 90% r.h. Water addition to the hazelnuts increased the rate and amount of hydrolysis of TAG by both A. flavus and A. niger. During storage some partial glycerides were also formed.