What is fining, how do common fining agents work, and when would you use them?

• A. Fining removes haze-causing or off-flavor compounds by binding them to agents like bentonite, gelatin, or isinglass; used to improve clarity, stability, and flavor balance when needed.
• B. Fining adds flavor compounds to increase intensity.
• C. Fining is a process of removing alcohol.
• D. Fining uses heat to sterilize wine.

Answer: (D)

Fining is a clarification and stabilization step in winemaking. It works by binding haze-causing or off-flavor compounds to specific agents so they can be removed from the wine, improving clarity, stability, and balance.

Common fining agents target different substances. Bentonite, a clay, binds proteins that can cause haziness in white wines, helping to keep the wine clear. Gelatin and isinglass (a type of collagen from fish) are proteins that interact with tannins and certain phenolics, helping to soften tannin bite, adjust mouthfeel, and in some cases stabilize color. PVPP binds polyphenols and related compounds that can contribute bitterness or browning, helping to refine flavor and appearance without removing too much color.

You’d use fining when a wine shows instability or haze, or when you want to improve clarity, stability, and flavor/aroma balance before bottling. It’s a corrective step, and dosage and choice of agent matter because overdoing it can strip desirable flavors or affect color. Heat treatment or alcohol removal aren’t part of the fining process.