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Healthy wine grapes, courtesy Flickr user Bensheldon

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!

Cayenne peppers, courtesy Flickr user ArielAmanda

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.

An active 2008 wildfire season affected some northern California wineries. Image courtesy of Flickr user rskoon

Vintners in two of the world’s biggest wine-producing regions, California and South Africa, have been fretting lately, and not just about the global recession. At least the economy affects all grape-growing nations more or less across the board. But the problem these winemakers have is decidedly site-specific: something seems to be happening to their terroir (the geographic characteristics of their growing region) that has them terrified.

Strange flavors are not necessarily a bad thing in wines. For instance, some good Bordeaux are described as having hints of leather. But certain aromas are decidedly rank and have no business being in your beverage. Among these, I would have to say, is burnt rubber.

That’s the bouquet ascribed to many South African wines by a tart-tongued British wine critic, Jane MacQuitty of The Times of London. As Barry Bearak reported in the New York Times, MacQuitty caused a stir in 2007 when she wrote that many of the reds she tasted from the country were tainted by a “peculiar, savage, burnt rubber and dirt odour.” She later called several top-rated South African wines “a cruddy, stomach-heaving and palate-crippling disappointment.”

This scathing string of adjectives stung the region’s winemakers, who felt the burnt rubber comments portrayed all South African wines as being, well, tarred with the same brush. Now scientists in the department of viticulture and oenology at Stellenbosch University are trying to figure out the source of the acrid aroma, and if it even exists. As molecular biologist Florian Bauer, who is heading the team, told Bearak, “We were not even sure what smell we were looking for. This research is a response to an ill-defined description in a newspaper.”

The subjectivity of flavor (and the suggestibility of tasters) is another problem. André van Rensburg, the winemaker at the Vergelegen Wine Estate, said critics at tastings “talk each other into a frenzy… If one of them picks up the taste of apple, the other guy says, ‘Yes, yes, and I taste cinnamon too.’”

Meanwhile, the question vexing winemakers in California’s Sonoma and Mendocino Counties is not what’s affecting their terroir, but how to deal with it. The rampant Northern Californian wildfires of 2008 subjected their grapes to a significant amount of smoke, according to an article by Jon Bonné in the San Francisco Chronicle. Although white wines have been relatively unaffected by the smoke, red wines, which contain more of the compounds from the grape skins, are more likely to be affected by “smoke taint.”

A smoky aroma is not necessarily a bad thing in wine. In fact, sometimes winemakers age their product in toasted barrels specifically to capture the scent. But, Bonné wrote, an ashy taste on a wine’s finish “can be bitter and almost throat-scratching.”

Australia, another significant wine-producing country, dealt with a similar wildfire problem in 2003. Winemakers there used reverse osmosis and other filtration techniques to remove the smoky compounds, a path being pursued in some California wineries.

Others are taking a laissez-faire approach, and allowing the smoky undertones to stay, Bonné says, as a “signature of terroir.” As one winemaker told him, “Each vintage has its character and talks about the place and the year. That’s a big part of honest winemaking.”

As I wrote last week, hot weather often makes people reach for chilly white wines. But there’s no reason to reject reds!

Although most people think red wines taste best at “room temperature,” that’s not as warm as you might think, especially in summer. Between 60-65 degrees Fahrenheit is ideal for most red wines, and some taste good even colder. Put the bottle in the fridge for a few minutes before serving, or for a fun touch, use frozen red grapes as ice cubes that won’t water down your wine.

Here are some types I like (based partly on a recent Smithsonian Resident Associates tasting with wine educator Kelly Magyarics):

Type: Pinot Noir
One to try: Domaine Chandon Pinot Noir, from the Carneros region of California
Average retail price: $30
Tastes like: Plums, blueberries and pepper
Pairs with: Cedar-planked grilled salmon, orange-glazed seared duck breast, BBQ chicken, lentil salad.

Type: Malbec
One to try: Trivento Select Malbec, from the Mendoza region of Argentina
Average retail price: $12
Tastes like: Dark berries, pepper and cocoa
Pairs with: Peppercorn-crusted beef, BBQ ribs, pizza with spicy toppings, Caprese salad.

Type: Cabernet Sauvignon
One to try: Solaire Cabernet Sauvignon Central Coast, made with Cabernet Sauvignon grapes from three of Robert Mondavi’s vineyards in California
Average retail price: $15
Tastes like: Blackberries, plums and vanilla
Pairs with: Grilled ribeye steak, lamb kebabs, hard cheeses.

Type: Beaujolais
One to try: Louis Jadot Beaujolais Villages, made with Gamay grapes from the Beaujolais region of France
Average retail price: $11
Tastes like: Strawberries, licorice and pepper
Pairs with: Hamburgers, grilled fish or chicken with Cajun spice rub, mild to medium cheeses.

Type: Rosé
One to try: Toad Hollow Eye of the Toad Rosé, made with Pinot Noir grapes from California’s Sonoma Valley
Average retail price: $10 (2007 vintage)
Tastes like: Strawberries, watermelon with a slight zing of citrus
Pairs with: Fried chicken, hot dogs, sushi, melon balls…pretty much anything!

A glass of white wine on a sunny day, courtesy of Flickr user iansand

Wondering which wines to pack for picnics or bring to barbecues this summer?

White wines tend to be more popular in hot weather, since they’re served chilled. Look for types described as light and crisp, rather than rich or full-bodied. As a general rule, wines aged in stainless steel tanks rather than oak barrels will keep more of their crisp, fruity taste—oak can add a buttery quality because of malolactic fermentation.

Here are a few suggestions, gleaned in part from a recent Smithsonian Resident Associates event with wine educator Kelly Magyarics.

Type: Sauvignon Blanc
One to try: Emiliana Natura, made with 100 percent organic Sauvignon Blanc grapes from Chile’s Casablanca Valley
Average retail price: $11
Tastes like: Limes, green apples, lemongrass
Pairs well with: Salad of mixed greens and herbed goat cheese, steamed clams with lemon butter, sushi, chips and salsa.

Type: Prosecco
One to try: Cantine Maschio Prosecco Brut, made from 100 percent Prosecco grapes in Italy’s Veneto region
Average retail price: $12
Tastes like: Fizzy, with peach-almond flavor. Like champagne, but less yeasty because it’s fermented in the tank instead of the bottle.
Pairs well with: Oysters, shrimp, fried chicken, avocado salad, prosciutto-wrapped melon balls. Mix with orange juice to make mimosas!

Type: Gavi
One to try: Vigne Regali Principessa Gavia, made from Cortese di Gavi grapes in Italy’s Piedmont region
Average retail price: $13
Tastes like: Apples and grapefruit with a whiff of pineapple
Pairs well with: Pasta salad, grilled lemon pepper shrimp or chicken, pesto dip.

Type: Torrontes
One to try: Crios de Susana Balbo Torrontes, from the high-altitude Cafayete region of Argentina
Average retail price: $15
Tastes like:  A tropical garden full of fruits and flowers; smells sweet but tastes dry
Pairs well with: Peanut satay skewers, grilled mango shrimp, fruit salad, salami, Gouda and most cheeses.

Type: Gruner Veltliner
One to try: Meinhard Forstreiter Grooner, made from Gruner Veltliner grapes in Austria’s Kremstal region
Average retail price: $9
Tastes like: Green apples and lime with a hint of mineral
Pairs well with: Fish tacos, grilled asparagus, pineapple chicken skewers, artichoke dip.

Glass of migraine-inducing (or not!) red wine. Courtesy of Flickr user ralphunden

If a genie granted me three wishes, one of them might be for a wine that wouldn’t give me a migraine. For those of you fortunate enough to have never had a migraine, it feels a little like having a dentist drill pierce your skull from base to forehead. The fact that drinking wine, especially red wine, has about a 50-50 chance of making my head feel that way has put a bit of a damper on my oenophilia. Hence my wish.

The genie in this case is Hennie van Vuuren, a researcher at the University of British Columbia’s Wine Research Center. He has figured out how to genetically alter yeast to remove the headache-inducing properties of red wine and many white wines. As James McWilliams at the Atlantic Food Channel reports, the genetically modified (GM) yeast, called ML01, which became commercially available in 2006, converts malic acid to lactic acid, eliminating compounds called biogenic amines that can cause headaches and allergies.

It sounds great, but there’s always a catch with those wily genies (at least the ones in jokes). In this case, the problem is that many people oppose genetically modified organisms (GMOs). Among the concerns are that GMOs could have unintended consequences for human health, including allergic reactions and the potential for transfer of antibiotic-resistant genes from foods to people. Another worry is that GMOs could cause a decrease in biodiversity. The information service ProQuest has an explanation of some of the issues surrounding GMOs.

In a commentary in the Napa Valley Register around the time the yeast became available, Erica Martenson argued that the FDA’s designation of ML01 as GRAS (Generally Recognized as Safe) was faulty. She asserted that the GM yeast could contaminate the wine yeast of neighboring wineries through the air, waste or water runoff.

GMOs are already in our food supply, and unlike in Europe, United States labeling laws don’t require producers to list the presence of GM ingredients. This is a cause for concern for American vintners, Martenson writes, because GMO-averse consumers in Europe and elsewhere may avoid U.S. wines altogether.

Rather than banning GM yeast, as some countries have done, McWilliams proposes that vintners using ML01 should voluntarily label their wines as genetically modified to reduce the chance of headaches. He contends that many consumers would consider the benefit to outweigh the potential risk.

As much as I share some of the concerns over GMOs, I have to admit, one of those consumers would probably be me.