Comparison of nitrogen and oxygen demands of enological yeasts: Technological consequences

Nitrogen and oxygen requirements of commercial yeasts were compared. Nitrog en demands were measured by calculating the amounts of ammoniacal nitrogen necessary to keep the fermentation rate constant during the stationary phas e. Oxygen demands were studied by (i) running anaerobic fermentations and ( ii) measuring the effect of adding 1 mg/L oxygen at the beginning of the st ationary phase. Substantial differences were found and their technological impact was discussed. Because of the importance of nitrogen and oxygen in e nology, using such tests may be of great interest, especially when there ar e risks of (i) slow fermentations, due to nitrogen deficiencies or (ii) slu ggish fermentations, mainly due to oxygen limitations.