SFist has been seen wandering the wine aisles at our Trader Joe's many a day and night. We mainly shop for wine by price - not for what may be added to the wines we drink. Not for long! The newly passed Food Allergen Labeling Consumer Protection Act (FALCPA) will mandate clear and consistent labeling of foods containing known allergens, starting in 2006. Since we are on our way to Napa this weekend, we found a recent article in The Chronicle very interesting. They asked, what exactly is in our wines these days?

Well, milk, eggs, fish, and copper may have been used along the way...even if we are left with just grapes in the end. They are classified as "fining agents", and be completely removed from the wine before bottling. Fining agents are added to a tank or barrel of wine to improve clarity, aroma, and to help during long-term storage. Different fining agents are used for different wines. One popular agent used in red wine is called polyvinyl polypyrrolidone, or PVPP. PPVP is used to remove very small molecules, so it helps in reducing bitterness. Small tannins (substances used in dyeing, tanning, and as an astrigent) are bitter; fining agents help in removing these tannins.

Another common addition to wine is acid. The Chron mentioned, "wines that don't have enough acidity can taste flat". Acid additions, such as ascorbic acid, don't change a wine's smell, but can make it taste more tart. If a wine already tastes more tart, winemakers may add potassium bitartrate to balance it out.