Proteomic characterisation of wine yeast strains for the expression of arginases involved in urea formation during fermentation
Christians, Lucinda Jo-Anne
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Wine is a fermented beverage widely consumed all over the world as a recreational drink, but is known for its health benefits to humans. However, wine contain urea, a by-product of arginine hydrolysis by arginases expressed during fermentation by the wine yeast Saccharomyces cerevisiae, which reacts spontaneously with ethanol to form ethyl carbamate (EC). Ethyl carbamate was implicated in toxicity and carcinogenicity. Subsequently, small scale (18 L) Sauvignon Blanc and Cabernet Sauvignon winemaking trials using commercial wine yeasts were initialised during the 2014 and 2015 vintages to measure urea in final wines. The overall aim of this study was to investigate wine yeast protein expression during alcoholic fermentation and establish a possible correlation between urea formation by wine yeast and up/down regulated yeast proteins. Ion-exchange chromatography in conjunction with spectrophotometry was used to measure urea levels in bottled wines. The yeast strain, Prise de Mousse (PdM) was shown to be the lowest urea producer in both Sauvignon Blanc and Cabernet Sauvignon wines.