ABSTRACT
A fast, sensitive and reproducible method using LC-MS/MS for simultaneous quantification of glutathione (GSH), glutathione disulfide (GSSG) and glutathione-S-sulfonate (GSSO3H) was developed, optimised and applied in analysis of grape juice and wine samples. The results show that only GSH (10-60 mg·L-1) and GSSG (2-11 mg·L-1) are found in grape juice when SO2 is not added. GSSO3H was detected in must samples treated with SO2 but only at a low concentration (<1 mg L-1). In the wine samples, the dominant form of glutathione was GSSO3H (5-11 mg L-1), followed by GSH (0-5 mg L-1) and GSSG (0-6 mg L-1), underscoring the importance of GSSO3H quantification. GSSO3H formation in wine was correlated with the total SO2 level in the wine. We believe this is the first report on GSSO3H quantification in wine.
Subject(s)
Vitis , Wine , Chromatography, Liquid , Glutathione/analysis , Glutathione Disulfide/analysis , Tandem Mass Spectrometry , Wine/analysisABSTRACT
Often blamed for bringing green aromas and astringency to wines, the use of stems is also empirically known to improve the aromatic complexity and freshness of some wines. Although applied in different wine-growing regions, stems use remains mainly experimental at a cellar level. Few studies have specifically focused on the compounds extracted from stems during fermentation and maceration and their potential impact on the must and wine matrices. We identified current knowledge on stem chemical composition and inventoried the compounds likely to be released during maceration to consider their theoretical impact. In addition, we investigated existing studies that examined the impact of either single stems or whole clusters on the wine quality. Many parameters influence stems' effect on the wine, especially grape variety, stem state, how stems are incorporated, when they are added, and contact duration. Other rarely considered factors may also have an impact, including vintage and ripening conditions, which could affect the lignification of the stem.
