An invertase fragment responsible for improving the protein stability of dry white wines

Abstract

The thermoprotective effect of yeast parietal mannoproteins improves the protein stability of white wines aged on their lees (sur lie). The substance responsible for this is an N-glycosylated, 31.8 kDa mannoprotein that corresponds to a parietal invertase fragment of Saccharomyces cerevisiae. This mannoprotein is released into the wine during autolysis of the lees by the combined action of β-glucanases from the cell wall and the yeast's vacuolar protease. This mannoprotein may be obtained industrially by extracting yeast mannoproteins using enzymatic digestion of the cell wall with commercially prepared β-glucanases (GlucanexTM -Novo-Nordisk). A wine's susceptibility to protein breakdown may be considerably reduced by adding this mannoprotein extract. As a result, less bentonite is needed to stabilise the wine. © 1999 Society of Chemical Industry