Understanding Wood Polysaccharide Depolymerization and Denaturation Under Different Toasting Conditions Through Analysis of Sugars Extracted from French Oak Chips

By analyzing the sugars extracted from oak chips toasted at various temperatures (180 to 280 °C) for various durations (10 to 30 min) in a model wine, we examined how wood polysaccharides are affected by toasting. The responses induced by toasting significantly differed among the major sugars constituting the wood. The main components of wood polysaccharides—glucose, arabinose, galactose, and xylose—were analyzed, and the results showed that galactose had the highest extraction amounts at around 220 °C of toasting, xylose at around 240 °C, and glucose at around 280 °C. On the other hand, the extraction amounts decreased with longer toasting durations. These results suggest that wood polysaccharides undergo temperature-dependent depolymerization while simultaneously undergoing denaturation. In addition, these depolymerization reactions tended to shift towards lower temperatures with longer toasting durations. The results of this study elucidate the chemical changes that occur within the wood during the toasting of oak chips and highlight the importance of the relationship between toasting temperature and duration. Additionally, this study demonstrated that by using the sugars extracted from oak chips as indicators, it is possible to partially visualize the reactions that occur within oak chips during toasting.