sorbic acid (2,4-hexadienoic acid), winemaking additive and preservative discovered in 1940 to inhibit the growth of yeast and other fungi. Sorbic acid, or its salt potassium sorbate, is used widely in food and drink production to inhibit the growth of yeast and mould, notably on cheese and meat. It is classified as one of the safest food preservatives. Sorbic acid use has permitted the wide range of everyday commercial wines currently available which contain some residual sugar but whose alcoholic strength alone is not sufficient to inhibit yeast metabolism.