Nitrogen Supplementation of Grape Juice. I. Effect on Amino Acid Utilization During Fermentation

Abstract

The effect of supplementation of grape juice with diammonium phosphate (DAP) and arginine on consumption of amino acids during grape juice fermentation was examined in two commercial yeast strains, UCD 522 (Montrachet) and Prise de Mousse. Both strains displayed similar patterns of amino acid uptake during fermentation and seemed to be affected similarly by nitrogen supplementation. Nitrogen supplementation increased fermentation rate of both strains, and had a significant effect on biomass production for Prise de Mousse but not for UCD 522. The correlation between juice nitrogen content and fermentation rate was stronger in UCD 522 as compared to Prise de Mousse. Supplementation with low levels of DAP (0.23 g/L, the legal allowable limit for nitrogen supplementation) had very little impact on amino acid utilization in this juice. Very high levels of DAP (2.0 g/L) greatly decreased both the consumption and degradation of arginine provided in the medium. The presence of the polyamines putrescine, spermine, and spermidine decreased utilization and degradation of arginine significantly, but less strongly. The combination of polyamines and DAP at high concentration did not completely prevent degradation of arginine.