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

The thermoprotective effect of yeast parietal mannoproteins improves the pr otein stability of white wines aged on their lees (sur lie). The substance responsible for this is an N-glycosylated, 31.8 kDa mannoprotein that corre sponds to a parietal invertase fragment of Saccharomyces cerevisiae. This m annoprotein is released into the wine during autolysis of the lees by the c ombined action of beta-glucanases from the cell wall and the yeast's vacuol ar protease, This mannoprotein may be obtained industrially by extracting y east mannoproteins using enzymatic digestion of the cell wall with commerci ally prepared beta-glucanases (Glucanex(TM)-Novo-Nordisk). A wine's suscept ibility to protein breakdown may be considerably reduced by adding this man noprotein extract. As a result, less bentonite is needed to stabilise the w ine. (C) 1999 Society of Chemical Industry.