title: Application of the SPI (Saliva Precipitation Index) to the evaluation of red wine astringency.
abstract: The aim of this work was to evaluate the astringency of red wines by means of a SDS-PAGE based-method. The optimization of the in vitro assay, named SPI (Saliva Precipitation Index) that measured the reactivity of salivary proteins towards wine polyphenols, has been performed. Improvements included the choice of saliva:wine ratio, saliva typology (resting or stimulated saliva), and temperature of binding. The LOD (0.05 g/L of condensed tannin) and LOQ (0.1g/L of condensed tannin) for the binding reaction between salivary proteins and tannins added in white wine were also determined. Fifty-seven red wines were analysed by the optimised SPI, the Folin-Ciocalteu Index, the gelatine index, the content of total tannins and the sensory quantitative evaluation of astringency. A significant correlation between the SPI and the astringency of red wines was found (R(2)=0.969), thus indicating that this assay may be useful as estimator of astringency.
authors.affiliation: Dipartimento di Scienze degli Alimenti, Università di Napoli Federico II, Facoltà di Agraria, Via Università 100, 80055 Portici (NA), Italy. alessandra.rinaldi@unina.it
authors.forename: Alessandra
authors.initials: A
authors.lastname: Rinaldi
authors.forename: Angelita
authors.initials: A
authors.lastname: Gambuti
authors.forename: Luigi
authors.initials: L
authors.lastname: Moio
mesh_terms: D001252:Astringents / Q000737:chemistry*; D004591:Electrophoresis, Polyacrylamide Gel / Q000379:methods*; D006801:Humans; D008954:Models, Biological; D059808:Polyphenols / Q000737:chemistry; D011485:Protein Binding; D012463:Saliva / Q000737:chemistry*; D012471:Salivary Proteins and Peptides / Q000737:chemistry; D013649:Taste; D014920:Wine / Q000032:analysis*
chemical_list: D001252:Astringents; D059808:Polyphenols; D012471:Salivary Proteins and Peptides