Wine related articles
What’s In That Bottle of Wine You’re
Drinking?
You will soon
see new information on wine labels.
[Dan Berger strikes again in his crusade to educate the wine drinking public. The following is an edited version of his 9/2/04 article in the San Francisco Chronicle.]
Fish bladders, eggs, copper, milk -- are they really in that bottle of Syrah? They might have been at some point. Winemaking may be called an art, but there’s plenty of science involved in the process, and some of the substances thrown in the tank along the way might surprise you.
Almost all of this stuff has been removed by the time the wine reaches the bottle, so what you end up drinking is grapes and little else. But some chemical secrets of winemakers will be unveiled by the new Food Allergen Labeling and Consumer Protection Act signed into law in August 2004, by President Bush.
Milk, eggs, and fish are potential allergens, and each is used in winemaking. All three are part of a class of substances called fining agents, and in theory all are completely removed from the wine before bottling. Fining agents are just one class of chemicals used during the winemaking process to give grape juice a makeover. Some winemakers also use flavor enhancers and correctors, coloring agents, and yeast nutrients.
Perhaps the most famous wine additives are sulfites which concern people enough to already merit their own warning label. Sulfites are crucial for preventing wine from spoiling and have been used in some form for centuries. Recent research appears to acquit sulfites of culpability for “Red Wine Headache Syndrome,” but some asthmatics may react to their presence.
It would be nice if vegans, asthmatics, or anyone sensitive to a particular additive could scan the bottle’s label to see a list of everything that has gone into making the wine. But until labeling laws change drastically, sensitive wine drinkers will have to settle for calling the winery for information about additives. Most people have no reason to think about what might have been in the wine they’re drinking, and never would think about it except when they’re prompted to ask, “Hey, what are those things floating in my glass?”
Fining
Agents
Fining agents remove elements that could affect the appearance or
texture of the wine. For example, winemakers seeking to soften the
texture of a highly tannic red wine might add egg whites or gelatin.
Fining agents are added to a tank or barrel of wine. The substance grabs
onto whatever solid matter it has an affinity for, and over a number of
days carries it to the bottom. The wine is then drained off leaving the
residue and the fining agent behind.
Different fining agents are used for different purposes. Isinglass, an extremely pure gelatin produced from the bladders of sturgeon, is used mostly in white and sparkling wines to improve visual clarity and purify aroma. Bentonite, a volcanic clay, removes proteins for better clarity as well as stability during long-term storage. Egg whites are used almost routinely in red Bordeaux and are also used to remove bitterness from Sherry in Jerez, Spain. Once it was common throughout that district to see Sherry houses separating eggs to use the whipped whites for fining the wine. What became of the yolks? Restaurants all over the district would routinely offer dishes with béarnaise and hollandaise sauces!
One fining agent popular with red-wine makers is a substance similar to ground-up nylon called polyvinyl polypyrrolidone, PVPP for short. A patented product of GAF Corp., PVPP is used to remove the pink color from some white wines. Because it can remove very small molecules, it also helps reduce bitterness. Small tannins are bitter; larger tannins are less so. Removing the smaller ones is helpful to keeping a red wine from being bitter.
A new technology accomplishes the same task in a different way. Vinovation, a Sonoma County technical consulting firm, uses a patented French process called micro-oxygenation that helps small tannin molecules clump together. [Fewer, larger arrays of tannin have much less contact with the mouth than dispersed molecules because they have less surface area. The resulting wine is perceived as less tannic.]
Flavor
Correctors
The most common addition to wine is acid. Almost all wines in California
have their acid “adjusted,” which is winespeak for an addition of acid
to accommodate for a deficiency. Insufficient acidity makes a wine taste
flabby or flat. Acid additions do not change the aroma of a wine, but
can increase tartness. Most acids supplements are natural, such as
tartaric or citric.
Tartaric acid, in fact, is the strongest and most common naturally occurring acid in wine grapes. It’s responsible for glass-like crystals, or tartrates, that form in some chilled bottles, often just under the cork. While completely harmless, the crystals taste as tart as the acid they come from. They’re often removed in the winemaking process, mostly for visual effect, and some wineries collect and sell them to companies that make cream of tartar which is used to help cake rise.
A few winemakers also use trace amounts of ascorbic acid (vitamin C) in some early-drinking white wines. It acts as an oxygen scavenger and keeps the wine fresher. What if a wine is already too tart? Some winemakers add potassium bitartrate which does the trick.
Consumers love the flavors of vanilla and wood that come from oak barrels. But new oak barrels are expensive, so makers of inexpensive wines sometimes take a shortcut, adding oak chips or even powder to a wine being made in a cheaper container. The oak is removed before bottling, but that oaky flavor remains.
Flawed wines can sometimes be “rescued.” Wines that have developed hydrogen sulfide (H2S), and thus are termed “reduced,” can have a rotten egg smell. Copper sulfate is a common solution to deal with H2S. The copper reacts with the H2S to eliminate the stink. Copper has its drawbacks because it is also an oxidation catalyst and can shorten the life of a red wine.
But copper can be the consumer’s friend. When you get a wine that has a slight hint of that rotten egg smell, drop a penny into the glass and after a minute or two the H2S smell should drop or be wiped out. Old pennies have more copper than newer ones and work better.
Coloring
Agents
For years, dark Petite Sirah and Alicante Bouschet were routinely added
to pale-colored red wines. They, however, add flavors of their own, and
even as little as 2 percent can sometimes dominate the taste of a more
delicate varietal.
Over the last decade, a number of companies have developed stable color additives, including one introduced in 2001 by Canandaigua Concentrate, a division of the wine company of the same name. Called MegaNatural, the substance is derived from grape skins and, according to the company, “can be custom-formulated into a wide range of shades of red, including Pink Grapefruit, Strawberry, Cranberry Red, Cherry, Raspberry, and the variations in-between.”
Yeast
Nutrients
Yeast is essential in the winemaking process, for it converts the sugar
in the grapes to alcohol. If the yeast dies off before fermentation is
complete, the remaining sugar will make the wine sweet, like a dessert
wine. Yeast nutrients -- the most common is diamonium phosphate, a
nitrogen source -- contain vitamins and amino acids that keep yeasts
healthy so a wine can completely ferment to dryness.
“The best tactic,” said Clark Smith, winemaker and president of Vinovation, “is to have healthy fruit come in, and that means grapes picked at moderate sugars. Well-balanced grapes normally contain all the nutrition that a healthy fermentation needs. It’s when you get underripe or very ripe fruit that you run into problems.”
Preservatives
Like all food products, wine can be made without preservatives. But
while the idea is appealing, the reality is a problem for a product that
people routinely store for a decade or more before consuming.
Without sulfites -- the most common wine preservative -- many wines would spoil before ever reaching your local wine shop. Sulfites are a naturally occurring part of the fermentation process, and winemakers have used sulfur dioxide as a preservative in one form or another for hundreds of years. Today a compound like potassium metabisulphite is added in tiny amounts at more than one stage during the fermentation process, and it releases sulfur dioxide that inhibits the growth of mold, vinegar-causing bacteria, and other unwanted micro-organisms. It also prevents the wine from oxidizing.
I often hear people implicate sulfites as the cause of a physical ailment they may have. I never heard those complaints until 1987 when the government began mandating that the phrase “Contains Sulfites” be attached to any product that contained more than 10 parts per million of sulfites. Dried fruit contains sulfites in more massive doses than in wine, but no one ever complains about ailments from dried pears.
Red Wine Headache (RWH) is an actual syndrome, but studies have shown that the cause isn’t sulfites. More likely it’s histamines, naturally occurring compounds found in animals and plants. “In wine, the amounts of histamine and tyramine are generally pretty small, and by themselves wouldn’t cause any problems, but you have this alcohol which inhibits the body’s defense system,” says Mark Daeschel of the Department of Food Science and Technology at Oregon State University. “Ethanol acts as an MAO inhibitor.” He said people who take MAO inhibitors (a class of antidepressants) are warned not to ingest foods that have histamines, and that should include red wine.
Some asthmatics have reactions triggered by sulfites, although a researcher in the field says wine doesn’t contain enough to be dangerous to most people. “The research I have seen shows that reactions to sulfites are dose- related, and I have failed to find a find a reaction below 250 parts per million,” said Dr. Keith Marton, chief medical officer of Legacy Health System and clinical professor of medicine at Oregon Health and Sciences University in Portland. The legal limit for U.S. wines is 350 parts per million; UC Davis studies show California wines average 80 ppm.
Marton adds: “There is at least one well-designed study that showed that red wine drinkers had less asthma than non-wine drinkers.” Still, asthmatics and others worried about sulfite can find wines with none added such as Frey Vineyards in Redwood Valley. Winemaker Jonathan Frey admitted that his winery has had “our ups and downs (making organic wine).”
“With modern winemaking equipment, I think it’s possible to make a sulfite-free wine,” Frey says. “If you have healthy fruit and get a clean fermentation, the wine is stable.” “To me, making wine without sulfites is like climbing Mt. Everest without an oxygen mask,” said Vinovation’s Smith. “People will say you’re crazy, but you might be able to do it.“
Frey says, “We aren’t making wines for long-term storage. We recommend that people drink our reds within five years of the harvest.” And if there are any floaties in it, or in any of your wines at home, relax. It’s not a problem.
THE QUICK AND DIRTY ON WHAT IS (OR HAS BEEN) IN YOUR WINE
A: These are tartrates (cream of tartar) and are harmless. Tartrate crystals, a natural by-product of fermentation, can be removed by winemakers who chill the wine (called cold stabilization) or filter out the crystals. Some believe that filtration diminishes the wine’s character, so they leave the wine unfiltered. If you don’t like the wine’s appearance, decant it before service.
Q: What about that sludge in the bottom of my glass?
A: Wine sediment is made up of naturally occurring solids that are harmless but can taste bitter. Like tartrate crystals, sediment sometimes remains in bottled wine because the winemaker has chosen not to fine or filter it. Again, decanting removes sediment.
Q: I’m a vegan; how will I know if animal products like egg whites, fish bladders, or gelatin have been used to make a particular wine?
A: While only trace amounts, if any, of these additions appear in the finished wine, strict vegetarians and those with religious concerns still want to know if animal products were used in production. Wines labeled “unfined” will not have any animal products in them. However, not all unfined wines say so on the label, and fined wines generally don’t state that on the label either. The only way to know is to call the winery and ask.
Q: Are there non-animal fining agents?
A: Yes, including bentonite, which is a type of clay, and polyvinylpolypyrrolidone (PVPP), which is similar to ground-up nylon.
Q: What are sulfites and why are they in wine?
A: Sulfites are sulfur compounds found naturally on fresh grapes and in all wines; winemakers can also add them to wines to inhibit the growth of mold and vinegar-causing bacteria, and to prevent oxidation. Sulfites play an important role in preserving wine’s freshness, yet are also a health concern to those few who are allergic or sensitive to them. Wines without added sulfites can be labeled as “sulfite-free” if the levels are under 10 parts per million.
Dan Berger is a freelance wine writer in Sonoma County. E-mail him at wine@sfchronicle.com.
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