Glucose Oxidase in Conjunction with Catalase – An Effective System of Wine pH Management in Red Wine

Background and goals

High grape pH directly influences the quality of the subsequent wines. Acidulation of grape juice and grape must by tartaric acid is a common practice but can leave a wine's flavor unbalanced. Treatment with commercially available Catazyme 25 L, which contains the enzymes glucose oxidase (GOx) and catalase, was investigated as a valid way to lower high pH in red grape juice/must while simultaneously increasing acidity and lowering glucose and potential alcohol.

Methods and key findings

Tempranillo must and juice were treated with Catazyme 25 L at two concentrations (0.5 g/L and 1 g/L) over a 24-hr period under continuous aeration. Chemical and sensory analyses were performed on the resulting wines. Results indicated that the pH of Tempranillo juice was decreased by 0.84 when using Catazyme 25 L at a rate of 1.0 g/L. Similarly, addition of Catazyme 25 L at 0.5 g/L decreased pH from 4.6 to 4.0 and 3.8 in the must and juice, respectively. Use of Catazyme 25 L led to production of lower alcohol wines due to conversion of glucose to gluconic acid. Sensory evaluation of the wines indicated a positive impact of the enzyme blend on color, aroma, and in-mouth flavor.

Conclusions and significance

GOx in conjunction with catalase is an effective pH management system, and of particular value for winemaking in hot climates, where it can also help lower alcohol concentration while positively impacting the sensory profiles of the wines.