Grape marc, also known as grape pomace, is an underutilized biowaste composed predominantly of grape skin and seeds that is produced as a byproduct of winemaking on the million-tonne scale annually. The most important high-value current use of grape marc is in the production of oenological tannins, widely used additives in the food and beverage industry. More commonly, grape marc is simply either disposed of or used as feed or fertilizer. With recent evidence showing that extracts enriched in grape tannins contain significant amounts of the thiol precursors Cys-3SH and GSH-3SH and the possibility that these could influence food and beverage aroma, it was decided to investigate grape pomace extraction procedures in order to try to define extraction protocols that could maximize the recovery of these compounds from grape marc. Should such an extraction protocol be shown to be commercially viable, this could lead to further utilization of material that would otherwise be disposed of. Two thiol precursors and...