Can Pepper Save Wine Grapes?

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Occasionally, winemakers find a silver lining in rotting grapes, but most of the time, rot is just plain rotten. It ruins the grapes' natural taste and thus the flavor of the wine.

In the United States, one of the most common culprits is bitter rot (greeneria uvicola), a sneaky fungus that hides its presence until the grapes are ripe. As the unsuspecting grower prepares for what might look like a great harvest, the latent spores stage a coup, turning the grapes soft, brown and pimply in a matter of days.

If as little as 10 percent of infected grapes make it into a pressing, it can make the whole batch of wine undrinkable (the taste, as the name implies, is horribly bitter). Obviously, this is a problem!

But a Louisiana microbiologist named Tony De Lucca has come up with an unusual solution: Cayenne pepper. Well, technically just one component of it, a saponin called CAY-1 that he named and patented in 2001, along with several colleagues at the USDA's Agricultural Research Service. They've been studying its anti-fungal properties ever since, and have discovered dozens of promising applications for both agriculture and medicine.

Recently the group reported another victory for CAY-1: This potent little pepper compound can be a lethal foe for bitter rot.

This discovery was prompted when a local vineyard called to report some diseased grapes. The scientists collected samples, isolated the fungi and put each type in a test tube with varying concentrations of CAY-1. It proved highly effective against greeneria uvicola, as well as several secondary pathogens.

"It begins to kill within ten minutes (in the test tube)," says De Lucca.

He's been fascinated by medicinal plant compounds for a long time, he adds.

"If you look in other cultures, particularly in hot areas around the equator, they use a lot of spices, and I think they use it in part to protect against bacteria. Things like thyme, oregano and garlic have some really potent anti-microbials."

Much more testing and a commercial backer are needed to develop CAY-1 into a marketable product, but it could potentially become an organic alternative to common synthetic fungicides. (And no, the wine wouldn't taste like pepper!)

"I think nature is just chock full of stuff like this," De Lucca says. "It's just a matter of looking."

For another angle on the connection between spice and fungus, check out this recent Smithsonian feature about the chili-hunting ecologist Joshua Tewksbury.

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