Wine Dilution Affects the Reliability of Tannin Analysis by Protein Precipitation.
Special Symposium - Innovations in Food Technology (LMC Congress)
Innovations in Food Technology - Poster Session (Food - P2)
Keywords: wine, quality, analysis
Tannins play an important role in the mouthfeel properties and color stability of red wines and are therefore related with wine quality. Reliable quantitative analysis of wine tannins is challenged by the chemical diversity of tannins and the analytical methods available. The purpose of this study is to investigate the influence of dilution degree on the reliability of tannin analysis by protein precipitation. The method relies on that tannin can be separated by precipitation with bovine serum albumin and measured by a color reaction with ferric chloride. Dilutions of five commercial red wines were analyzed by protein precipitation and the linear relationship between the inverse dilution factor and the measured tannin content was evaluated. Although linear relationships were generally observed, all wines caused negative intercepts, which can be explained by the theory of a precipitation threshold. In addition, several dilutions with high tannin content deviated from the linear relationship, probably due to insufficient protein for the precipitation step. Considering the substantial impact of the intercept for highly diluted wines and the need for sufficient protein for the precipitation step, we have defined a valid range of the tannin measurements, where the tannin precipitation suffers minimally from the described problems.
Presented Thursday 20, 13:30 to 14:40, in session Innovations in Food Technology - Poster Session (Food - P2).
