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The Grapes Ripen (Finally!)

Though the grapes have been maturing slowly, the fruit hanging on the vines has almost completely turned red during the process called véraison. In other posts I’ve used the term véraison quite a bit and briefly explained its meaning but didn’t go into much detail. It is a borrowed French word meaning “the onset of ripening” and in English it is defined as the “change in the color of the grape berries”. Up until this point in the life cycle of the vine they have been expending their energy dividing and expanding the cells which form the grapes. The reddening of the grapes mark the moment that growth stops and ripening begins. The green turns to the familiar red hue of the grapes as chlorophyll breaks down and new pigment molecules such as anthocyanins are formed.

The acidity in the grapes begins to decrease as sugar accumulates. You may be familiar with the measurement Brix which is the percentage of sugar in the juice. Each week, the grapes will gain about 1.5ºBrix until they are fully ripened, usually at around 25ºBrix. Depending on the varietal, the winemaker may choose to harvest the fruit well before they become this sweet. Brix may rise further due to dehydration of the berry with no further sugar being produced.

This year I’ve really enjoyed watching the vines transform from little more than twigs into great leafy hedges. I’ve been eating the grapes throughout the growing season even when they were so sour they made my face pucker. It wasn’t until véraison occurred that they started to actually taste like grapes. The vines have a finite amount of energy available to produce the fruit. The trick is to channel that energy into producing high-quality, fully-ripened berries.


You hear the phrase “dropping fruit” a lot this time of year. It means removing clusters of grapes so that each vine has fewer bunches with the aim of producing more flavorful grapes. This is definitely something that distinguishes the wine industry from other agricultural industries: Growers get paid by yield, like every other farmer, but many are dedicated to quality and are willing to reduce yield to increase quality. At this point some of the clusters are lagging behind – while most of the bunches have reached 100% véraison, a few stragglers still have half of their green berries left. These bunches will never fully ripen and in the meantime just sap the energy out of the vine that could be used to ripen the other grapes. These green bunches will be cut off and sacrificed to help ripen the rest.

The crew is busy cleaning the winery in preparation for the incoming fruit but the harvest is so late this year that it’s likely they will finish well before the first grapes arrive. We’ll be using this downtime to send the crew into the vineyard to drop under ripe bunches and remove any grapes that raisined due to sun burn during the heat wave last week. Usually the grapes laid bare to the sun have a chance to tan, thus protecting them from sunburn. This year they never tanned. It was too cold. When the heat wave hit and temperatures got up to 105º these exposed berries got burned. Most of these bunches will be culled along with the green bunches.

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Reader Comments (1)

Thanks so much for explaining this today at Crush and for the in depth explanation in your article. This is great. Wonderful!

September 19, 2010 | Unregistered CommenterAlyssa

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