title: Relationship between nitrogen content in grapes and volatiles, namely heavy sulphur compounds, in wines.
abstract: Ammonium salts were added to white grape musts, before alcoholic fermentation, in order to evaluate their influence on the heavy sulphur compound and aliphatic higher alcohol composition of resulting wines. Six grape musts were used (Trajadura, Pedernã, Loureiro, Azal Branco, Avesso and Alvarinho). Ammonium supplementation of Trajadura and Pedernã grape musts, with the highest nitrogen level, did not influence the content of heavy sulphur compounds and aliphatic higher alcohols in wines; however, the addition of ammonium salts to grape musts with low initial nitrogen content, such as Loureiro, Azal Branco and Avesso, led to a higher production of 1-propanol and a lower production of isoamyl alcohols and sulphur compounds, e.g. S-methyl thioacetate, 2-mercaptoethanol, acetic acid-3-(methylthio)propyl ester, 3-mercapto-1-propanol, 4-(methylthio)-1-butanol, 3-(ethylthio)-1-propanol, 3-methylthiopropionic acid and N-3-(methylthiopropyl)acetamide. For Alvarinho grape must, a decrease in sulphur compound concentrations in wines was only observed for 3-methylthiopropionic acid, acetic acid-3-(methylthio)propyl ester and 2-mercaptoethanol.
authors.affiliation: CBQF/Centro de Biotecnologia e Química Fina, Escola Superior de Biotecnologia, Universidade Católica Portuguesa, Rua Dr. António Bernardino de Almeida, 4200-072 Porto, Portugal; REQUIMTE/Departamento de Toxicologia, Faculdade de Farmácia, Universidade do Porto, R. Aníbal Cunha 164, 4050-047 Porto, Portugal. Electronic address: nemoreira@mail.esb.ucp.pt.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Moreira
authors.affiliation: REQUIMTE/Departamento de Toxicologia, Faculdade de Farmácia, Universidade do Porto, R. Aníbal Cunha 164, 4050-047 Porto, Portugal.
authors.forename: Paula Guedes
authors.initials: PG
authors.lastname: de Pinho
authors.affiliation: CBQF/Centro de Biotecnologia e Química Fina, Escola Superior de Biotecnologia, Universidade Católica Portuguesa, Rua Dr. António Bernardino de Almeida, 4200-072 Porto, Portugal.
authors.forename: Cristina
authors.initials: C
authors.lastname: Santos
authors.affiliation: CBQF/Centro de Biotecnologia e Química Fina, Escola Superior de Biotecnologia, Universidade Católica Portuguesa, Rua Dr. António Bernardino de Almeida, 4200-072 Porto, Portugal.
authors.forename: Isabel
authors.initials: I
authors.lastname: Vasconcelos
keywords: Aliphatic higher alcohols; Ammonium salts; Fermentation; Nitrogen; Sulphur compounds; White wines; Yeast nitrogen consumption