Which of the following are commonly used fining agents?

• A. Bentonite, gelatin, or isinglass.
• B. Acetic acid, sugar
• C. Lemon juice, salt
• D. Oxygen gas

Answer: (A)

Fining agents are substances added to wine to clarify and stabilize it by binding particles that cause haze or instability and helping them settle out. Bentonite, gelatin, and isinglass are classic examples. Bentonite is a mineral clay that binds proteins, which helps prevent protein haze, especially in white wines. Gelatin and isinglass are protein-based fines; they attach to tannins and other colloidal particles, aiding their removal and giving a clearer wine. The other options don’t function as fining agents: acetic acid or sugar are used for different purposes in winemaking, while lemon juice, salt, and oxygen gas don’t act to clarify or stabilize wine.