Toni CORDENTE, Australian Wine Research Association (AWRI), Australia
Across the wide range of commercial yeast strains available to winemakers, there is substantial variation in their production of aroma compounds. Some desirable compounds are not typically produced at high enough concentrations to make a difference to wine aroma and flavour. Examples include the yeast-derived compounds 2-phenylethanol (2-PE) and 2-phenylethyl acetate (2-PEA), which are associated with ‘rose’ and ‘floral’ aromas in wine, as well as in other fermented foods and beverages (Cordente 2012). Generally, the concentrations of these ‘rose’ aroma compounds in wines are below their aroma sensory thresholds, particularly in white wines, so their potential contribution to wine aroma is considered to be minimal (de-la-Fuente-Blanco 2016; Vilanova 2013).
By using classical yeast strain development techniques, more than forty non-genetically modified (non-GM) yeasts that produce high concentrations of both ‘rose’ aroma compounds 2-PE and 2-PEA were generated at The Australian Wine Research Institute (AWRI) (Cordente 2018). These ‘rose’ yeasts were isolated from three different parent Saccharomyces cerevisiae strains, with each having different fermentation volatile profiles and competitive fitness characteristics that might suit different winemaking styles.
Three of these ‘rose’ yeasts were extensively trialled at pilot scale over the last four vintages to assess wine styles that may be compatible with enhanced ‘rose’ aroma characteristics, including white, rosé, red and sparkling wines. In addition, by selecting ‘rose’ yeast that produce different amounts of 2-PE and 2-PEA (moderate and high), it was possible to finetune concentrations for specific wine styles.