Grape Seed Color

According to the wine mythos, the changing color of a grape's seed has played a role in determining when winemakers harvest grapes. Jim Harbertson, WSU professor of enology says that long-held belief might not be so.

HARBERTSON: It's well know in grapes that the seeds sort of change color during the grape ripening process. They start out when the fruit's not very ripe, it's really green and then as the fruit gets riper the seeds tend to get browner and browner. Wine makers have long sort of thought that as the seed got more and more brown that that meant there would be less tannins. Wine makers don't want too much tannin in the red wine, they want some tannin in the red wine so that way they can kind of balance the astringency with the alcohol and flavors and everything.

Experiments done in Australia took a really hard look at the various color of seeds but Harbertson says they decided to test that.

HARBERTSON: We can pick fruit from the same vineyard at different times and we could change some things in the wine that would help to extract more of the seed tannin and see if it really and truly changes how much tannin you get out of the seeds based on when you make a picking decision. In the end we learned that it didn't really matter when you picked, the amount of the tannin you got out of the seeds really didn't change that much that went into the wine. The color change didn't really affect the tannin extraction.

The researchers aren't telling winemakers to make changes to how they've operated for years, but they do hope the study leads to re-evaluation of when winemakers harvest their grape crop.

That's today's Fruit Grower Report. I'm Greg Martin on the Ag Information Network of the West.