Simultaneous determination of ketoacids and dicarbonyl compounds, key Maillard intermediates on the generation of aged wine aroma

Abstract

The aim of thiswork was the simultaneous determination of both ketoacids and dicarbonyl compounds in wine.Todetect ketoacidcompoundsin wine,amethodbasedonthequinoxaline derivativesby the reaction with diaminobenzene, currently employed to detectα-dicarbonyl compounds, was developed. The quinoxaline derivatives were detected by RP-HPLC with UV detection, which allows the determination of the major dicarbonyl compounds in wine: glyoxal, methylglyoxal, diacetyl and pentane-2,6-dione, and the quinoxaline/quinoxalinol derivatives of α-keto-γ-(methylthio)butyric acid and β-phenylpyruvic acid (intermediate ketoacid compounds of methional and phenylacetaldehyde) were simultaneously detected by a fluorescence detector. The identification was performed by comparison with standards and also by using LC-MSMS. The levels found in 15 wines analyzed (white wines,Madeira wines, and Port wines) diverge according to the type and the age of the wine. The ketoacid compounds ranged from 0.2 to 5.7 mg/L for α-keto-γ-(methylthio)butyric acid and 0.1 to 9.6 mg/L for β-phenylpyruvic acid. The quantities observed for dicarbonyl compounds were similar to those already reported