Clarifying agents and 3-sulfanylhexanol precursors in grape juice

To evaluate if certain common clarifying agents impact on S-3-(hexan-1-ol)-L-cysteine (Cys-3SH) and S-3-(hexan-1-ol)-L-glutathione (GSH-3SH) concentration in juice, 19 well settled and clear grape juices enriched indirectly with the cited thiol precursors were treated with Na-bentonite, PVPP or charcoal (1 g/L), cold settled again, and compared with the corresponding untreated control juices. The thiol precursors were measured by UHPLC-MS/MS, while accuracy was guaranteed with deuterated internal standards. Only charcoal caused a statistically significant depletion of Cys-3SH and GSH-3SH, but quantitatively limited even with the high dose adopted. The clarifiers used affect the thiol precursors of juice in technologically marginal manner.