Abstract

Wine grapes (Vitis vinifera L.) have been historically harvest according to their soluble solid contents, (>22.5%) and tartaric acidity (6-7 g·L-1). However, the phenolic content has been proposed and used lately as a better index to determine harvest date. This has implied to delay harvest significantly which has favoried the development of molds that can affect must and wine qualities. The mold incidence found in 13 Cabernet sauvignon vineyards at harvest varied from 4.7 to 66.7%, and were identified as olive green molds (Cladosporium herbarum, Alternaria alternata, Ulocladium sp.), gray mold (Botrytis cinerea), dark brown mold (Aspergillus niger), and Phoma sp. These fungi species, with the exception of B. cinerea, were not necessarily associated to rotten berries. C. herbarum and A. alternata were the most frequently species, found in 11 and 7 of 13 sample sites studied, respectively. Weight of moldy grapes was significantly lower than weight of apparently healthy grapes (p < 0.05), with 32.8% overall mean weight loss of the 13 Cabernet sauvignon vineyards. Wines produced with moldy grapes had consistently lower color capacity, a yellowish tint, and had lower contents in antocianins and total phenol. These wines had lower free sulfur dioxide content but combined sulfur dioxide content increased considerably. Additionally, relative to must from apparently healthy grapes, fermentation was delayed at least 12 days when moldy grapes were used. Therefore, the relative high incidence of molds found on wine grapes at harvest reduced yields and had a negative effect on wine qualities, particularly reducing wine color, and affecting smell and flavor. Consequently, the present tendency of Chilean wineries to postpone harvest to obtain a better wine quality does not necessarily fulfill this goal.