Decomposition of Organic Acids in Wines by Yeast and Lactic Acid Dacteria

Abstract

Uronic acids (gluconic, galacturonic and glucuronic acids) in sound wine grape musts (seven varieties), normal (20 samples) and botrytized wines (11 samples) were determined. Average of total amounts of three uronic acids in the sound grape musts was 0.40 g per liter. Botrytized wines contained a large amount of gluconic acid and a considerable amount of galacturonic acid. A significant amount of galacturonic acid was found in normal red wines.
Further, we investigated the decomposition of uronic acids and main organic acids in Koshu grape must by Sacch. cerevisiae IAM 4274 and Leuconostoc mesenteroides var. lactosum 234. Uronic acids was slightly decomposed in the fermented musts by Sacch. cerevisiae; 8-10%. Uronic acids gave weak sour and astoringent taste to wine and enhanced the thickness. Gluconic and glucuronic acids in the incubated musts decreased significantly in accordance to malo-lactic acid fermentation by Leu. mensenteroides var. lactosum. Citric acid in the musts was perfectly utilized by the malo-lactic bacteria. It is suggested that D-lactic and acetic acids are formed by the gluconic acid metabolism by the bacteria.