PT  - JOURNAL ARTICLE
AU  - Leo P. McCloskey
TI  - Enzymatic Assay for Malic Acid and Malo-Lactic Fermentations
AID  - 10.5344/ajev.1980.31.3.212
DP  - 1980 Jan 01
TA  - American Journal of Enology and Viticulture
PG  - 212--215
VI  - 31
IP  - 3
4099  - http://www.ajevonline.org/content/31/3/212.short
4100  - http://www.ajevonline.org/content/31/3/212.full
SO  - Am J Enol Vitic.1980 Jan 01; 31
AB  - A rapid enzymatic method for the determination of malic acid in grape juice and wine is presented which is designed for monitoring malo-lactic fermentations in the said liquids. The results allow for the calculation of malate levels and therefore of malo-lactic fermentation rates. This particular enzymic assay for malic acid uses malate dehydrogenase and glutamate oxaloacetate transaminase for accelerating the main enzymic assay reaction catalyzed by malate dehydrogenase. The assay reactions utilize the photometric determination of NADH at 340 nm. In five minutes the analyst can detect up to 2000 mg/L malate and in seven minutes up to 4000 mg/L. Essentially 100% of the malic acid is recovered with a standard deviation of better than 35 ppm.