Effect of Lactic Acid on Volatile Acid Determination of Wine

Abstract

The influence of lactic acid on the volatile acidity of wines was determined by three methods: a microdiffusion method; a steam-distillation method; and a new method developed from a modification of the steam-distillation technique. The new method employed the use of mercuric oxide to complex the sulfur dioxide in the wine samples. This modified method showed good correlation of results with those obtained by the standard steam-distillation procedure.

All three methods resulted in low recoveries of lactic, acid from wines containing various levels of lactic acid. The diffusion method had less than 0.5% recovery and the two distillation methods about 2%. If was concluded that increases in volatile acidity of wines having undergone a malo-lactic fermentation is probably the result of the formation of acetic acid, the production of lactic acid contributing little increase.