EFFECTS OF β‐GLUCOSIDASE ACTIVITY ON THE CHARACTERISTICS OF AROMATIC RED RICE WINE

Abstract

The pigment in the bran layer of aromatic red rice (Oryza sativa var. Indica, Tapol) is rather stable, has a characteristic red color just like that of grape wine and has a peak of absorbance at 530 nm at an acidic pH. A commercial saccharifying agent, glucoamylase AN‐2, produced by Aspergillus niger was fractionated to separate glucoamylase and β‐glucosidase activities by column chromatography on CM Sephadex C‐50. The red rice wine made from uncooked, unpolished aromatic red rice using the fractionated, β‐glucosidase‐free preparation of glucoamylase had a characteristic red color. By contrast, red rice wine made with glucoamylase AN‐2, which contained β‐glucosidase activity, was inferior in color. The red pigment of aromatic red rice wine was decolorized and glucose originating from the red pigment was released by enzymatic digestion with the fractionated preparation of β‐glucosidase. The partial decolorization of aromatic red rice wine was ascribed to the enzymatic action of β‐glucosidase that was present in glucoamylase AN‐2. Thus β‐glucosidase activity has an undesirable effect on the brewing of aromatic red rice wine. 1994 The Institute of Brewing & Distilling