Sauvignon blanc is the most important grape cultivar within the New Zealand wine industry, and wines from the Marlborough region are renowned for their intense aromas including tropical, passionfruit, and green capsicum. Quality Sauvignon blanc wines are usually made from free run juice, although press fractions can be included. The chemical aroma composition and sensory profiles of two wine sets made from three press fractions (free run, light press and heavy press) were compared. The compounds 3-mercaptohexan-1-ol and 3-mercaptohexyl acetate were found to decrease between free run and heavily pressed wines while hexyl acetate, hexanol, and benzyl alcohol increased. The accompanying sensory analysis showed that free run wines were marked by aromas of Passionfruit/sweaty, Boxwood and Fresh green capsicum, while the heavy pressed wines were described by French vanilla/bourbon, Floral and Banana lolly attributes, consistent with the aroma chemical composition.
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.
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