Clarifying Agents And 3-Sulfanylhexanol Precursors In Grape Juice

We evaluated the impact of a number of clarifying agents on the concentration of S-3-(hexan-1-ol)-L-cysteine (Cys-3SH) and S-3-(hexan-1-ol)-L-glutathione (GSH-3SH). 19 clear grape juices were spiked with a grape skin tannin rich in Cys-3SH and GSH-3SH. Juices were then treated with Na-bentonite, PVPP or charcoal (1 g/L) and cold settled. The concentration of precursors was measured and compared to the corresponding untreated control juices in the devatted samples. Cys-3SH and GSH-3SH were analysed using UHPLC-MS/MS and accuracy was guaranteed with deuterated internal standards. Only charcoal caused a statistically significant depletion of both precursors, quantitatively limited even at the highest dose adopted. Technologically, the clarifiers used in juice affected the thiol precursors in a marginal manner.