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 the polysaccharide profile and content from white musts and cava sparkling base wines have been studied. Fungal beta-D-glucans could not be detected in musts and wines obtained from grapes contaminated by B. cinerea. The direct 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 polysaccharides rhamnogalacturonan II is increased three-fold in the wine obtained from contaminated grapes. Arabinogalactan content increased also although to a lower extent. As expected, yeast mannoproteins were not affected by the previous contamination of grapes. The decrease in filterability of wines 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.