Changes in the urea content of wine under different fermentation and agingconditions by two Saccharomyces cerevisiae races

Urea, ammonium, arginine and ornithine contents after fermentation and biol ogical aging of wine for two Saccharomyces cerevisiae strains with differen t O-2 levels were analysed. Yeast growth and the excretion or uptake of ure a were both dependent on yeast strain and the fermentation conditions. Base d on these results, flor yeasts can metabolize the urea produced during fer mentation in the event of arginine being depleted in the process. However, if any arginine remains after fermentation, then the urea concentration inc reases during the veil formation period.