Sleuthing Out What's In Wine (Part one of four)
|Sleuthing out what's in wine: Sturgeon bladder in your bubbly? You'd be surprised at the stuff that's paid a visit to what you're drinking.|
|Chronicle illustration by Bill Russell|
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 last month 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 chemical used during the winemaking process to give grape juice a makeover. 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 floaties in my glass?"
Let's find out.
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 egg whites or gelatin.
Fining agents are added to a tank or barrel of wine. The substance grabs onto whatever solid matter it's targeted 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.
The different fining agents are used for different purposes. Isinglass, an extremely pure gel 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 in removing 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 bearnaise 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. Also, because it can remove very small molecules, it helps reduce bitterness. Small tannins are bitter; larger tannins are less so. Removing the smaller ones is thus 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 make small tannins large.
Part 1 • (2 • 3 • 4 – to be published)
|Dan Berger is a freelance wine writer in Sonoma County.
Originally Published on ©2004