Yeast assimilable nitrogen in South Moravian grape musts and its effect on acetic acid production during fermentation

Abstract

We observed the content of yeast assimilable nitrogen in grape musts, its consumption by yeasts during fermentation, and acetic acid production. The experiments were performed in the years 2007 and 2008. The experimental variants involved 48 musts and wines originating fromSouthern Moravia. The data enabled to monitor the contents of yeast assimilable nitrogen in musts and to draw the general conclusion that these musts contain high concentrations of both ammonium ions and yeast assimilable nitrogen (124.4 mg/l and 257.8 mg/l, respectively), thus posing no danger of problems with the nutrition of yeasts in the course of fermentation. Also, the average production of acetic acid was low (215.8 mg/l); this indicated that in the majority of must samples without added nutrients, the course of fermentation was smooth and trouble-free. The results obtained confirm that the method of formaldehyde titration is universal and simple, thus it can be recommended for winemakers as a useful and efficient analytical tool.