Yeast protein extracts: an alternative fining agent for red wines

Wine producers have to label the use of certain animal proteins for fining of must and wine since 2012 [regulation (EC) No. 579/2012] under specific conditions, which has encouraged the search for alternative fining agents produced out of plants or yeasts. Yeast proteins are naturally present in wine and first studies of yeast protein extracts (YPE) for the fining of wine have been published, which were mainly focused on the technical properties of the YPE as fining agents. The present study used YPE of different production techniques for fining of red wine and evaluated their technical properties. Furthermore, the sensory effect of the new fining agents, their protein composition and the presence of glycans and glycoproteins were examined. The YPE showed differences in their protein profile and in protein glycosylation, but all YPE that were investigated were successfully applied for fining of red wine. Mannoproteins were detected in all YPE, and they did not prevent the mutual precipitation of proteins and tannins that is necessary for successful fining as reported earlier in case of glycans and glycoproteins. The chemical parameters of the red wine were modified by fining with YPE in a way comparable to fining with gelatine, a traditional fining agent used as reference, and the initial quality of wine flavour was maintained during the treatments.