Definition - What does Fining Agent mean?
A Fining Agent is a substance used during the Fining or clarification stage of winemaking. It is added to the wines in order to bond with the soluble substances that cause cloudiness, haze or could cause wine faults in a wine.
The theory behind fining agents is that the soluble substances have a specific electric charge (positive or negative); therefore, each fining agent has an opposite charge in order to allow them to bond with the unwanted particles. Positively charged fining agents include gelatin, egg albumen, isinglass and sparkalloid; negatively charged fining agents include bentonite and kieselsol.
WineFrog explains Fining Agent
There are two main types of Fining Agents: organic compounds and solid/mineral materials. These two categories are then divided into sub-categories.
Casein - derived from milk; used in white wines to remove undesirable odors, bleach color and clarify
Isinglass - derived from fish bladders; gentle alternative to gelatin usually used on white wines to clarify
Egg albumen - derived from egg whites; most commonly used to reduce harsh tannins in red wines
Clarifies overly astringent wines; used in conjunction with Kieselsol.
Bentontine Clay - effective in absorbing proteins and some bacteria
Sparkolloid - used to clarify wines after fining is complete
Carbons (from charcoal)
Activated carbons - removes some phenols that contribute to browning as well as some particles that produce "off-odors" in the wine.
Silica & Synthetic Compounds
Kieselsol - used in conjunction with gelatin in white wines for clarification and tannin reduction
Polyvinyl polypyrrolidone (PVPP) - used to remove bitter and browning compounds in red and white wines
Other possible fining agents include Kaolin, Carrageenan, copper sulfate, hydrated yeast, Alginate, Chitin, Gum Arabic and Pectin destroying enzymes.