title: Nitrogen requirements of commercial wine yeast strains during fermentation of a synthetic grape must.
abstract: Nitrogen deficiencies in grape musts are one of the main causes of stuck or sluggish wine fermentations. Currently, the most common method for dealing with nitrogen-deficient fermentations is adding supplementary nitrogen (usually ammonium phosphate). However, it is important to know the specific nitrogen requirement of each strain, to avoid excessive addition that can lead to microbial instability and ethyl carbamate accumulation. In this study, we aimed to determine the effect of increasing nitrogen concentrations of three different nitrogen sources on growth and fermentation performance in four industrial wine yeast strains. This task was carried out using statistical modeling techniques. The strains PDM and RVA showed higher growth-rate and maximum population size and consumed nitrogen much more quickly than strains ARM and TTA. Likewise, the strains PDM and RVA were also the greatest nitrogen demanders. Thus, we can conclude that these differences in nitrogen demand positively correlated with higher growth rate and higher nitrogen uptake rate. The most direct effect of employing an adequate nitrogen concentration is the increase in biomass, which involves a higher fermentation rate. However, the impact of nitrogen on fermentation rate is not exclusively due to the increase in biomass because the strain TTA, which showed the worst growth behavior, had the best fermentation activity. Some strains may adapt a strategy whereby fewer cells with higher metabolic activity are produced. Regarding the nitrogen source used, all the strains showed the better and worse fermentation performance with arginine and ammonium, respectively.
authors.affiliation: Departamento de Biotecnología de los alimentos, Instituto de Agroquímica y Tecnología de los Alimentos-CSIC, Avda. Agustín Escardino 7, E-46980-Paterna, Valencia, Spain.
authors.forename: Alicia
authors.initials: A
authors.lastname: Gutiérrez
authors.forename: Rosana
authors.initials: R
authors.lastname: Chiva
authors.forename: Marta
authors.initials: M
authors.lastname: Sancho
authors.forename: Gemma
authors.initials: G
authors.lastname: Beltran
authors.forename: Francisco Noé
authors.initials: FN
authors.lastname: Arroyo-López
authors.forename: José Manuel
authors.initials: JM
authors.lastname: Guillamon
mesh_terms: D018533:Biomass; D005285:Fermentation; D005511:Food Handling / Q000379:methods*; D008954:Models, Biological; D009584:Nitrogen / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000254:growth & development / Q000378:metabolism*; D027843:Vitis / Q000737:chemistry / Q000382:microbiology*; D014920:Wine / Q000032:analysis*
chemical_list: D010710:Phosphates; C024788:ammonium phosphate; D009584:Nitrogen