Influence of Botrytis cinerea on the polysaccharide composition of xarel.lo musts and cava base wines

Modifications induced by a spontaneous infection of grapes by gray rot on t he polysaccharide profile and content from white musts and cava sparkling b ase wines have been studied. Fungal beta-D-glucans could not be detected in musts and wines obtained from grapes contaminated by B. cinerea. The direc t pressing of grapes used for the production of sparkling base wines may be a limiting factor for the solubilization of fungal glucans into the must. Nevertheless, the concentration of the hydrolase-resistant grape pectic pol ysaccharides rhamnogalacturonan II is increased three-fold in the wine obta ined from contaminated grapes. Arabinogalactan content increased also altho ugh to a lower extent. As expected, yeast mannoproteins were not affected b y the previous contamination of grapes. The decrease in filterability of wi nes produced from contaminated grapes may be related to their high content in grape polysaccharides and not only to the presence of fungal BD-glucans whose extraction is related to the disruption of grape berry skins prior to pressing.