Technologies and strategies for the production of lower alcohol wine
There is interest from some consumers in wines with lower alcohol concentration that maintain robust aroma and flavour profiles. Producers may also face financial penalties for higher alcohol wines in markets where taxes are levied on the basis of alcohol concentration.
The microbial biodiversity of spontaneous fermentations contains great potential for shaping wine style, including the production of wine with reduced alcohol concentration. Harnessing this diversity in controlled, inoculated ferments may provide winemakers with simple, cost-effective and low risk strategies for tailoring wines to market demands. Non-conventional yeast (yeast other than Saccharomyces cerevisiae) have the potential to remove some fermentable sugar from must prior to inoculation with S. cerevisiae.
Sensory profile of wines produced by ‘lower-ethanol’ non-conventional yeasts
Semillon and Merlot musts were fermented with two non-conventional yeasts Saccharomyces uvarum and Metschnikowia pulcherrima. Both yeast strains were marginally effective in reducing alcohol concentration in fresh grape must due to competition with indigenous yeast populations. Dimethyl dicarbonate was therefore used to treat musts to reduce the indigenous microflora. Several treatments produced wines with lower ethanol concentration than control S. cerevisiae wines. Formal sensory analysis revealed that while wines fermented with S. uvarum, alone or in combination with M. pulcherrima, were lower in alcohol concentration, they were associated with negative sensory attributes. Wines fermented with M. pulcherrima were associated with positive sensory attributes and were lower in alcohol concentration than S. cerevisiae wines. Overall the results suggest that further work is required to render low-alcohol non-Saccharomyces yeasts more robust, and to ameliorate their potential negative sensory impacts.