Browning of white wines: correlation with antioxidant characteristics, total polyphenolic composition and flavanol content

Summary Browning is a serious problem in relation to white wine quality, which mostly affects the sensory attributes. It is well known to be associated with polyphenol oxidation, and therefore it may be accompanied by changes in the antioxidant capacity. On the basis of this consideration, thirteen experimental white wines, vinified and stored under identical conditions, were subjected to accelerated browning, and efforts were made to distinguish compositional parameters that might be related to the extent of browning development. Further, the relation of browning with the reducing power and the antiradical activity were assessed. Regression analysis at 95% significance level indicated that the antiradical activity is likely to be exerted principally by the flavanol fraction (r2 = 0.92) and to a lesser extent by total phenols (r2 = 0.85), as opposed to reducing power, which is mainly affected by total phenols (r2 = 0.78), suggesting that synergistic phenomena account for the overall antioxidant status of white wines. In addition, the total phenolic and flavanol concentration correlated significantly with the browning rate constants and provided strong evidence that browning development might be predominately associated with flavanol (r2 = 0.84) and to a lesser extent with total phenolic (r2 = 0.79) oxidation.