Approaches to prevent the light-struck taste in white wine

Abstract

Background and Aims The light-struck taste is a fault occurring in light-exposed white wine containing methionine and a high concentration of riboflavin (RF) and bottled in clear bottles. These conditions induce the formation of methanethiol and dimethyl disulfide, responsible for a cabbage-like aroma. In order to decrease the risk of wine spoilage, a low concentration of RF should be obtained in wine either by preventing RF release from yeast during winemaking or by removing RF from wine. Methods and Results Fifteen commercial Saccharomyces strains intended for the wine industry were tested for RF production, which was also evaluated when two yeast-based nutrients were added into the must for one of these strains. The RF released during vinification was strain-dependent and a concentration from 30 to 170 μg/L was found in wine. A high concentration of RF was released in the presence of the yeast-based nutrients because of either the yeast metabolism or the RF contained in the nutrient itself. The ability of different inorganic (bentonite, charcoal, zeolite, kaolin) and organic adjuvants (egg-white proteins, polyvinylpolypyrrolidone) to deplete RF in wine was evaluated. A relatively low level of charcoal (50 mg/L) removed up to 60% of RF in wine, although its effectiveness was related to the charcoal source. A high concentration of bentonite (1 g/L) was needed to effectively decrease the risk of wine spoilage. Conclusions A critical RF concentration in white wine can be prevented by applying one or more approaches in winemaking: using low RF-producing yeast strains in fermentation, selecting suitable yeast nutrients or adsorbing RF by insoluble charcoal or bentonite. Significance of the Study The research highlights suitable tools to prevent light-struck taste in white winemaking.