Deacidification of red and white wines by a mutant ofSchizosaccharomyces malidevoransunder commercial winemaking conditions

A mutant ofSchizosaccharomyces malidevorans, which utilizes malic acid more rapidly than the wild-type strain and does not utilize significant amounts of glucose or fructose, was used in commercial scale deacidification of grape juice during two vintages in a New Zealand winery. Four trials were conducted in Chardonnay, Semillon and Cabernet Sauvignon juices, 1000–4500 l. In the first two trials, the juices were inoculated with the alcoholic fermentation yeast,Saccharomyces cerevisiae, 33–48 h after the mutant inoculation. In the remaining two trials, the juices were inoculated simultaneously with the mutant andS. cerevisiae. Malic acid, ranging from 3.5–10 g l⁻¹in the juices, was completely degraded within 21–73 h. TheSchiz. malidevoransmutant utilized malic acid at sulfur dioxide levels and temperatures used in red and white winemaking. The wines produced in the trials lacked obvious organoleptic defects. They were blended with untreated wines for acid balance and retailed as varietal wines.