Comparative study of browning and flavan-3-ols during the storage of white sherry wines treated with different fining agents

White sherry wines were treated with three fining agents (activated charcoal, PVPP and Riduxhigh), in addition to an initial treatment with casein and bentonite, in four different combinations. The wines were stored at 20 or 30°C for 1 year with a view to examining changes in their flavan-3-ol fraction and differences in their degree of sensitivity to browning. Flavan-3-ol monomers and dimers, as well as browning measured as absorbance at 420nm, increased during storage in all the wines. After this period the wines treated with fining agents containing activated charcoal, PVPP and Riduxhigh exhibited less marked browning, with no significant differences among them at both 20 and 30°C. However, taking into account the higher initial colour of bottled wines treated with Riduxhigh in relation to those treated with activated charcoal or PVPP, this fining agent showed higher capacity to control browning.