Effect of holding temperature on the thiol potential of machine‐harvested Sauvignon Blanc grapes

Background and Aims Grape temperature changes attuned to day and night machine harvesting were investigated with respect to varietal thiol potential. Methods and Results Machine‐harvested Sauvignon Blanc grapes were held at 6, 15 or 24°C, for 2 h before pressing and fermentation, representing typical Marlborough Sauvignon Blanc transport times. Thiol precursors S‐3‐(hexan‐1‐ol)‐L‐cysteine and S‐3‐(hexan‐1‐ol)‐L‐glutathione were quantitated before and after temperature treatments. No significant difference was found for the concentration of S‐3‐(hexan‐1‐ol)‐L‐cysteine and S‐3‐(hexan‐1‐ol)‐L‐glutathione before the holding period, but after 2 h the juice held at 15°C had a significantly higher concentration of precursors than at 6°C. Following small‐scale fermentations, the concentration of 3‐sulfanylhexan‐1‐ol and 3‐sulfanylhexyl acetate in finished wines was not significantly different. Conclusions The holding temperature of machine‐harvested grapes can influence thiol precursor concentration but the typical transport time of 2 h does not alter thiol concentration. Significance of the Study Temperature changes during the grape holding period do not negatively impact thiols.