By Fergal Gleeson

If you’ve gunning down a road in wine country around midnight in early autumn, the lights you see are probably not a UFO’s. It’s unlikely to be a rave. Nor are you seeing a weirdo cult ritual. You are observing in their natural habitat the nocturnal movements of the winemaker!

Vintage is the time of year when vineyard managers and Winemakers put the pedal to the floor. Many work through the night during this period. I spoke a two Winemakers and a Viticulturist from Margaret River to understand this curious practice a little better.

So why pick grapes at night?

Janice McDonald, Chief Winemaker at Howard Park Wines, one of Western Australia’s leading wineries explains why.

“We pick at night because it’s the coolest part of day. Usually that is just before sunrise. When we talk about night picking we are talking about machine picking, as it is not possible to hand pick at night. Pickers would lose fingers!”

Janice explains the science behind night picking. “We are trying to minimise the oxidative impact of the enzymes in the grapes. There can be a particularly strong reaction in white grapes with strong aromatics such as Riesling or Sauvignon. We want to slow down the activity of enzyme.’’

Leonard Russell, Viticulturist with Watershed Wines, the highly awarded Margaret River winery adds “It’s about the optimisation of the fruit. When a machine picker shakes the berries off the vines it slightly damages the fruit.”

“Like if you take a bite from an apple and leave the apple out it turns brown. The equivalent with grapes would be a sultana flavour. By picking at night when it’s cool, we are slowing down this effect. Otherwise fermentation could start before the grapes reach the winery.”

So picking grapes at night when it is coolest, allows the winemaker to benefit from a natural chilling effect which protects the freshness of the grapes and the purity of the fruit flavour.

Leonard explains how a Machine Harvester works. “The machine straddles the row of vines and uses what look like shepherds hooks to move the vine left to right. The berries fall off the vine onto a conveyor belt.”

“Only the ripe berries fall off. The fruit passes through a series of fans where the leaves and stems are removed and the fruit goes onto a trailer which is checked for weight before being taken on to the winery.”

Ryan Aggiss, Chief Winemaker at Aravina Estate agrees citing the favourable impact on colour, flavour and the aromas from night picking.

Are red grapes also picked at night?

Leonard says that Watershed sometimes pick Shiraz at night or in the early morning if it’s being used for Rose. Because these grapes are picked earlier in the season when it’s still hot. For Cabernet and Merlot, which are harvested in March or April, night picking is less of an issue because the temperatures are getting cooler.

Janice agrees that there is nowhere near as big an impact with red grapes because reds are not as aromatic.

Interesting at Aravina Estate all machine harvested grapes are picked at night including red grapes. Ryan Aggiss, Chief Winemaker does this partly for pragmatic reasons because a wine workers biological clock is set to night picking during vintage, because the vineyards and winery are quieter and also because of the value of having the fruit nice and cool.

For Aravina’s table wines they start with picking the Chardonnay grapes, then it’s Semillon, Chenin, and Sauvignon Blanc through to Shiraz, Merlot, Cabernet and Tempranillo.

This feature originally appeared in the summer issue of Your Margaret River Region Magazine. All photos courtesy of Watershed Wines and Aravina Estate.