Today at work, while our system was down for the upteenth time this week, I was listening to a Wine Biz Radio podcast. Kaz and Randy were discussing the “stupid robbers” who in the middle of the night stole a couple tons of Cabernet Sauvignon grapes. The stupidity was that the grapes were still “green,” and not ripe enough to make decent wine.
While, I’m thinking “Why on earth would thieves steal Cabernet grapes that are still green?” Kaz says, “well they had already gone through veraison.”
Ah, I thought; someone who didn’t know better might assume they were ripe. What Kaz and Randy meant by “green” was that wine made from grapes picked too soon may impart some less-than-pleasant vegetal or heavy green pepper flavors. As we have posted in the past, we do not expect to find green pepper in a higher-priced Cabernet Sauvignon. Even though some bulk wine producers tell us one should expect green pepper in any sort of Cab.
AWB #17: So What is Véraison?
Véraison started out as a French word meaning “beginning to change color.” It’s been used in English to mean the intermediate stage of development where grapes go from hard little green bullets, to softened purple and black beauties of promise. It’s a step in the maturation of the grapes when they go from green to black. But just because they have changed color, does not mean they are ready to harvest. Veraison simply indicates the onset of ripening.
At the beginning of veraison, the berries are hard and green, and about half their final size. During veraison, the berries change skin colour and soften, sugars and volume increases, and acidity decreases. The colour of the grape before veraison is due to green chlorophyll, and at veraison berry skin changes colour to red-black or yellow-green depending on variety.
~ Jancis Robinson in The Oxford Companion to Wine
For any one grape berry, the inception of veraison is very rapid and dramatic. The grapes soften and in about a week begin to grow. Not all of the grapes in the bunch do this simultaneously, as you can see in the photo. The first grape berries to ripen are those most exposed to the sun, or in warmer micro-climates those closest to a stake, post or wall. Because these grapes benefit from the night time heat that has been retained or re-radiated. The last grapes to go through veraison are those in the canopy shade or on short shoots.
Veraison also depends on the amount of water going to the grapes. If there is water stress (when the grape grower withholds water or irrigation to the vines) veraison may be faster. Veraison is slower in vines with large crops, with many actively growing shoot tips and lots of shaded fruit.
And why, if the grapes look ripe, are they not ready to pick?
As grapes stress and hang on the vine a bit longer, it allows them to grow in size. It also allows more sugars to develop. After veraison, the acidity decreases, while the sugars increase. While an entire chapter of wine science could be devoted to explaining the process, suffice-it-to-say that the fruit flavor and alcohol increases, as the green pepper and vegetal flavors decrease.
So robbers who go in and harvest grapes before they are ready are either stupid, or a competitor trying to make sure his grapes are the only game in town.
So the take away here is this: Just because the grapes look ripe, they might not be ready to harvest to make fabulous wine.
And that’s Another Wine Byte; information you can use to impress your friends (but not in an obnoxious way, of course!)