Impact of glucose oxidase treatment in high sugar and pH musts on volatile composition of white wines

Abstract

Climate change is modifying the composition of the grapes, increasing sugar and pH levels, which produces unbalanced wines with high alcohol degree, low acidity and poor aromatic notes. In this study, glucose oxidase (GOX) and catalase (CAT) were applied in white must with high sugar content and pH (>3.8) to simultaneously decrease glucose concentration and pH. The effect of enzyme treatment on volatile composition of wine was investigated. A concentration of 0.17 mkat/L for both GOX and CAT was sufficient to produce a remarkable reduction of glucose concentration in the must (61.5 g/L), achieving similar results within the pH range of 3–4. The musts subjected to enzymatic treatment yielded more balanced wines, lowering their alcohol content by 10–27 mL/L and pH by 0.3–0.5, while leaving their chromatic characteristics unchanged compared to the control wines. As positive effects, enzyme treatment reduced the concentrations of C6-alcohols with green-herbaceous notes and high-chain ethyl esters with soapy notes in wines, and did not modify the concentrations of short-chain ethyl esters, acids and higher alcohols. However, the concentrations of heptyl acetate and 2-phenylethanol with floral notes, and some ketones with floral and fruit notes, were lower in wines from treated musts.