Partial purification of a polygalacturonase from a new Aspergillus sojae mutant and its application in grape mash maceration

Abstract

The use of polygalacturonase (PG) preparations in winemaking promotes the release of phenolic compounds. A PG from a new source, Aspergillus sojae mutant, was semi-purified and tested for grape mash maceration. Crude extract (CE), a commercial pectinase, and two high PG activity semi-purified preparations, F-I and F-II,F- were applied for maceration at PG activity of 3.5Ug(-1) of grape for 46h. Enzyme-assisted maceration significantly (P < 0.05) increased the total phenolic content from 255.8 to 916.3 +/- 5.2, 5732.9 +/- 9.9, 563.4 +/- 6.7 and 620.6 +/- 18.4mgL(-1) for CE, commercial pectinase, F-I and F-II, respectively. The content of individual phenolics such as gallic, protocatechuic, chlorogenic and p-coumaric acids was improved. Principal component and hierarchical clustering analyses suggested that CE has a better performance upon the release of phenols. Semi-purified preparations acted similar to commercial pectinase. These findings open an opportunity for the potential use of PG from the mutant strain as an alternative macerating enzyme.