A method is disclosed for hydrolyzing an alpha-1,5 glucosyl-fructose linkage in a saccharide (disaccharide or oligosaccharide) such as leucrose. This method comprises contacting the saccharide with an alpha-glucosidase enzyme such as transglucosidase or glucoamylase under suitable conditions, during which contacting step the enzyme hydrolyzes at least one alpha-1,5 glucosyl-fructose linkage of the saccharide. This method is useful for reducing the amount of leucrose in a filtrate isolated from a glucan synthesis reaction, for example.