Biological processes for the reduction of alcohol in wines

Abstract

A study was conducted into the effect of varying levels of aeration and temperature on the reduction of sugar and production of alcohol in Muller Thurgau grape juice by selected yeast strains. In addition, an assessment of the suitability of combining aeration with anaerobic fermentation to produce a reduced alcohol wine with acceptable colour and taste was undertaken. Of seven yeast strains which had shown promising results at reducing sugar levels in either apple juice or orange juice, three; Pichia stipitis, Candida tropicalis and Saccharomyces cerevisiae, individually produced significant alcohol reductions when fermented at 30 °C under controlled aeration. By combining short-term controlled aeration, to reduce the sugar content of the grape juice, with anaerobic fermentation using an active dried wine yeast, wines with acceptable taste and 25 to 30% less alcohol were produced. These wines did, however, exhibit the deep golden colour indicative of oxidation.