title: Influence of the timing of nitrogen additions during synthetic grape must fermentations on fermentation kinetics and nitrogen consumption.
abstract: Nitrogen deficiencies in grape musts are one of the main causes of stuck or sluggish wine fermentations. In the present study, we have supplemented nitrogen-deficient fermentations with a mixture of ammonium and amino acids at various stages throughout the alcoholic fermentation. The timing of the nitrogen additions influenced the biomass yield, the fermentation performance, the patterns of ammonium and amino acid consumption, and the production of secondary metabolites. These nitrogen additions induced a nitrogen-repressed situation in the cells, and this situation determined which nitrogen sources were selected. Glutamine and tryptophan were the main amino acids consumed in all the fermentations. Ammonium is the preferred nitrogen source for biomass production but was hardly consumed when it was added in the final stages of the fermentation. The higher ammonium consumption in some fermentations correlated with a greater synthesis of glycerol, acetate, and acetaldehyde but with a lower synthesis of higher alcohols.
authors.affiliation: Unitat d'Enologia del Centre de Referència de Tecnologia d'Aliments, Department Bioquímica i Biotecnologia, Facultat d'Enologia de Tarragona, Universitat Rovira i Virgili, Ramón y Cajal, 70, 43005 Tarragona, Spain.
authors.forename: Gemma
authors.initials: G
authors.lastname: Beltran
authors.forename: Braulio
authors.initials: B
authors.lastname: Esteve-Zarzoso
authors.forename: Nicolas
authors.initials: N
authors.lastname: Rozès
authors.forename: Albert
authors.initials: A
authors.lastname: Mas
authors.forename: José M
authors.initials: JM
authors.lastname: Guillamón
mesh_terms: D026905:Amino Acid Transport Systems / Q000235:genetics; D027682:Cation Transport Proteins / Q000235:genetics; D005285:Fermentation; D005511:Food Handling / Q000379:methods; D005638:Fruit; D015870:Gene Expression; D007700:Kinetics; D009584:Nitrogen / Q000008:administration & dosage* / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics; D027843:Vitis; D014920:Wine
chemical_list: D026905:Amino Acid Transport Systems; D027682:Cation Transport Proteins; C491145:GAP1 protein, S cerevisiae; C107270:MEP2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D009584:Nitrogen