Comparative protein profile analysis of wines made from Botrytis cinerea infected and healthy grapes reveals a novel biomarker for gushing in sparkling wine.

Fungal infection of grapes with the plant pathogenic fungus Botrytis (B.) cinerea was shown to cause a degradation of proteins in the resulting wine. Moreover, it influences the foaming properties of the wine. The aim of this study was to compare the protein composition in B. cinerea infected and healthy grapes and of wines produced from such grapes as well as to analyze whether the resulting changes in the protein profiles can be related the occurrence of gushing in sparkling wine. SDS-PAGE and reversed phase HPLC were applied to analyze the protein composition of healthy and botrytized grapes and of wines made from botrytized and healthy grapes. B. cinerea infection led to a general decrease of protein content in infected grapes and wines suggesting proteolytic activity of this fungus. Especially the concentration of a protein with a protein band at ~17kDa underwent a significant decrease in wine made from infected grapes. This protein was identified as Seripauperin 5 (PAU5) from Saccharomyces cerevisiae. A degradation of PAU5 and other proteins and the occurrence of a laccase from B. cinerea were observed in a gushing sparkling wine. Screening of sparkling wines showed that samples lacking PAU5 had a high probability for the occurrence of gushing. We suggest that the absence of protein PAU5 might be a useful biomarker for the occurrence of gushing in sparkling wine.