Grape harvest time and processing method can be used to manipulate ‘Sauvignon Blanc’ wine style
New Zealand 'Sauvignon Blanc' wine is characterised by a distinctive combination of tropical-passionfruit and green-herbaceous aromatic aromas. The volatile thiol compounds 3-mercaptohexan-1-ol (3MH) and 3-mercaptohexyl acetate (3MHA) are significant contributors to tropical aromas, whereas methoxypyrazines, isobutylmethoxypyrazine (IBMP), isopropylmethoxpyrazine (IPMP) and green leaf volatiles (GLVs) such as trans-2-hexenal and cis-3-hexanol, contribute to the green characters in the wine. Grape harvesting and processing methods can alter thiol:methoxyprazine ratio (tropical:herbaceous characters). We varied time of day of harvest and skin contact duration to manipulate 'Sauvignon Blanc' wine composition and style. Grapes were hand harvested at 0600, 1200 and 1800 h on the same day from the lower Wairau Valley, Marlborough, in 2013. Grapes, chilled to 8°C, were processed using three skin contact durations (0, 3 and 6 h) and were then pressed and fermented in 700-mL lots. There was a significant increase in thiol and methoxypyrazine concentrations in wine made from grapes receiving zero skin contact duration compared with 3 or 6 h skin contact. At a constant fruit processing temperature, grapes picked at 0600 h and given zero skin contact produced juices with significantly lower browning/oxidation (juice optical density at 420 nm) and wines with higher thiol concentrations. Results suggest that early morning harvests, minimal time from berry crushing to pressing and minimal juice oxidation will help to maximise wine thiol production providing a means to manipulate wine style in response to market demands or climate extremes.
Grose, C.H., Martin, D.J., Stuart, L., Albright, A. and McLachlan, A.R.G. (2016). Grape harvest time and processing method can be used to manipulate ‘Sauvignon Blanc’ wine style. Acta Hortic. 1115, 139-146
harvest method, volatile thiols, methoxypyrazines, skin contact duration, wine aroma