beta-Glucosidase activity in juice-processing enzymes based on anthocyanin analysis

A screening procedure utilizing boysenberry juice as a substate, which combined HPLC and spectrophotometric analyzes, was used to measure beta-glucosidase activity of enzyme preparations used for juice processing. Enzyme preparations (n = 26) were evaluated at two dosage rates. At the mean recommended dosage, one preparation produced a decrease in total monomeric anthocyanin and cyanidin-3-glucoside, relative to a control, indicating beta-glucosidase activity. At 0.1% dosage, 4 enzymes produced a significant decrease in cyanidin-3-sophoroside and 2 enzymes caused an increase in cyanidin-3-rutinoside, indicating beta-1,2-glucosidase activity. Such activity in juice processing enzymes was much lower and less prevalent than found previously for beta-galactosidase. Botrytis cinerea also degraded anthocyanins in boysenberry juice.