Decomposition of L-tartaric and L-malic acids in grape must by Botrytis cinerea.

Abstract

L-Tartaric and L-malic acids in grape must were remarkably decomposed on incubation of Botrytis cinerea IFO 5964 under the conditions of 15 to 25% sugar content and pH 2.5 to 3.5 at 15 to 27°C. MoreL-tartaric acid was degraded by the fungus than L-malic acid in the absence of glucose. Accumulation of ten organic acids was found in the mediumcontaining L-tartaric acid on incubation of B. cinerea. The main metabolites from L-tartaric acid with intact mycelia in 1/15 m phosphate buffer (pH 3.5 and 7.0) were L-lactic, acetic, D-glyceric, succinic, citric, L-malic, pyruvic and oxaloacetic acids. The improvement of tartrate stability and sensory evaluation was achieved in the wine made from Riesling grape must which was blended with the botrytized must.