Webster's dictionary defines fining to mean "to become pure or clear". This definition can be broadenedconsiderably. For wine, fining means toadd an adsorptive or reactive substance to reduce or remove the concentration ofone or more undesirable components. Fining agents are used to achieve clarity and to improve color, flavor and physical stability.Fining agents can be grouped according to their chemical nature and mode of action.
1. Earths: bentonite
2. Proteins: gelatin, isinglass, casein, albumen
3. Polysaccharides: agars
5. Synthetic polymers: PVPP
6. Silicon dioxide (kieselsol)
7. Others, including chelators and enzymes