Finings

Lore & Background

Finings have been used by some producers in traditional forms such as egg whites, blood, milk, isinglass, and Irish moss. More modern substances like bentonite, gelatin, casein, carrageenan, alginate, diatomaceous earth, pectinase, pectolyase, PVPP, kieselsol (colloidal silica), copper sulfate, dried albumen, hydrated yeast, and activated carbon are more widely used today. The actions of finings are broadly categorized as electrostatic, adsorbent, ionic, or enzymatic. Electrostatic finings, which comprise the vast majority, work by attracting oppositely charged particles in colloidal dispersions, forming a stable neutral complex that agglomerates into a semi-solid mass that can be separated. Adsorbent types include activated carbon and specialized fining yeasts; activated carbon can remove benzenoid compounds and all classes of polyphenols non-specifically, while yeast fining uses hydrated yeasts with cell walls that have chemical affinity for polyphenolic or metallic compounds. Ionic finings such as copper sulfate bind undesirable sulfides, and PVPP forms hydrogen bonds with phenolic hydrogens of polyphenols. Enzymatic finings like pectinase and pectolyase destroy pectin, which causes haze in fruit wines and juices, and are among the few finings added before fermentation.

Reader's Guide

Finings play a significant role in the production of wine, beer, and nonalcoholic juices by enabling producers to control clarity, flavor, and aroma. The electrostatic types are the most common and are used as a batch technique, selectively removing proteins, tannins, and coloring particles. Activated carbon and fining yeasts serve as adsorbent agents, with activated carbon capable of decolorizing and deodorizing juices and wines, and yeast fining providing a practical means of removing excess copper ions when copper sulfate has been used to bind volatile sulfur compounds. Copper sulfate and PVPP act through ionic mechanisms, with PVPP specifically targeting low molecular weight polyphenols rather than condensed tannins. Enzymatic finings address pectin haze before fermentation. However, the use of finings raises nutritional concerns because beneficial antioxidant flavonoids such as quercetin and catechin can be removed by certain finings like gelatin, casein, and PVPP. Additionally, because some finings are animal products and others are not, it can be difficult for consumers to determine whether a wine or beer is vegan or vegetarian unless the producer labels it as such; the website Barnivore maintains an international database classifying beverages as 'Vegan Friendly' or 'Not Vegan Friendly'.

Did You Know?

• Finings can remove sulfides, proteins, polyphenols, benzenoids, or copper ions from beverages.
• Yeast fining is a practical means of removing excess copper ions greater than 0.5 mg/L.
• Enzymatic finings like pectinase are among the few finings added before juices are fermented.