Fining Agents

Fining is the winemaking process, applied either before or after fermentation, in which adsorbent or reactive materials are added to juice or wine to reduce or remove less desirable components. As fining agents bind to suspended particles, for example by electrical interaction between opposite charges, they form larger particles that settle in the wine, after which the wine is racked or filtered off the deposit. The OIV lists three objectives: to complete spontaneous clarification when it is unsatisfactory, to soften red wines by removing some of their tannins and polyphenols, and to clarify wines with haze problems, stirred up lees or insoluble coloured matter. According to the AWRI, the fining agent reacts with wine components either chemically or physically to form a new complex that can separate from the wine. Fining is distinct from filtration: fining relies on the agent reacting with wine components chemically or physically, while filtration is a separate step that can follow it, and the OIV's Code of good fining practices calls for filtration to remove insoluble protein fining agents.

• Protein-based agents: gelatine, isinglass, egg white (albumen), casein, potassium caseinate and skim milk
• Bentonite (a very fine clay) and kaolin
• Synthetic polymer: PVPP (polyvinylpolypyrrolidone)
• Carbon: used to remove off-flavours, odours and colour
• Other agents admitted by the OIV: alginates, colloidal silicon dioxide solution, chitosan, chitin-glucan, yeast protein extracts and proteins of plant origin

The OIV's Code of good fining practices describes three ways fining agents bind with substances: electrical interaction, where the agent and the substances to be removed are of opposite charge and come together forming larger particles which settle in the wine; bond formation, where a chemical bond forms between them; and absorption and adsorption, where the substances are caught within the structure of the agent or bind onto its surface. Bentonite is a negatively charged clay colloid that reacts with positively charged proteins, precipitating them from the wine; because the positive charge on proteins is stronger at lower pH values, the AWRI notes that bentonite is more effective in wines with lower pH. Gelatine interacts mainly with larger polyphenolic compounds, while monomers and smaller polyphenolic compounds react easily with isinglass. Egg white protein binds with the larger polymeric material in red wine. PVPP absorbs the low molecular weight phenolics, especially anthocyanins and catechins, and carbon works by physical adsorption of compounds onto the large surface area of its particles.

• Bentonite: negatively charged clay colloid that precipitates positively charged proteins
• Gelatine: interacts mainly with larger polyphenolic compounds
• Isinglass: reacts easily with monomers and smaller polyphenolic compounds
• PVPP: absorbs low molecular weight phenolics, especially anthocyanins and catechins
• Carbon: physically adsorbs compounds onto the large surface area of its particles

Bentonite is principally used to remove proteins from white wine and juice, and the AWRI advises that its use in red wines should be limited because it can reduce colour by adsorption of anthocyanins. Sodium bentonite, calcium bentonite or combinations are common; calcium bentonites often require higher addition rates but are easy to hydrate and prepare and give compact lees, and so less wine loss. Gelatine is the most aggressive of the proteinaceous fining agents and can easily result in over fining and colour removal. Isinglass is principally used in white wine fining to bring out or unmask fruit character without large changes in phenolic levels, and its lees tend to be light and fluffy, so care is needed not to disturb them on racking or filtering. Egg white removes phenolic compounds associated with harsh astringency in red wines, leading to a softening and improved suppleness, and the AWRI notes it is often used when the wine is in barrel or prior to bottling. Casein, most commonly used as potassium caseinate, reduces phenolics linked to bitterness and browning in whites and Sherries but has limited clarifying action. PVPP is used to reduce phenolic compounds associated with browning and astringency in white wine and can also remove pink colour and pinking precursors; the AWRI describes it as a gentle fining agent which preserves wine aroma, unlike some other fining agents. The typical doses below are from the AWRI's fining agents guide, fetched in 2026.

• Bentonite: 200 to 1000 mg/L in white wine, 200 to 500 mg/L in red wine
• Gelatine: 15 to 120 mg/L in white wine, 30 to 240 mg/L in red wine
• Isinglass: 10 to 100 mg/L in white wine
• Casein: 50 to 250 mg/L
• PVPP: 100 to 800 mg/L in white wine, 100 to 450 mg/L in red wine; the OIV maximum is 80 g/hl
• Egg white: as a guide, 2 to 8 egg whites per 225 L of wine

The AWRI says the choice of fining agent depends on many factors, the most important being the destination market of the wine and the wine style sought by the winemaker. Gelatine is often added to white juice, and particularly pressings, to aid clarification and reduce phenolic compounds associated with bitterness, astringency and browning; in red wine it reduces phenolics associated with excessive bitterness and astringency and might also remove some colour. Bentonite fining is best performed on the final wine blend, after fermentation and after all proteinaceous fining, though some producers trial it towards the end of fermentation to aid yeast settling. Carbon can remove off-flavours and odours, decrease browning or pinking in white wines and remove colour from red wines, but the AWRI regards it as a severe and relatively non-specific fining agent. PVPP is not commonly used in red wines, though it can reduce bitterness and brighten the colour. According to WSET, natural wines have often undergone minimal clarification and filtration, and some producers avoid the fining process altogether and may use the term 'unfined' on the label.

• White wines and juice: bentonite for protein stability; gelatine and isinglass for clarity; casein and PVPP for bitterness and browning
• Red wines: gelatine and egg white for tannic wines; limited bentonite because it adsorbs anthocyanins
• Sherries: casein to reduce phenolic compounds associated with bitterness and browning
• Natural and unfined wines: minimal clarification and filtration; 'unfined' may appear on the label

WSET notes that many producers have historically used animal products for fining: egg whites, casein (derived from milk), isinglass (fish bladders) and gelatin (made by boiling pig skin), and that wines fined with the latter two would also not be considered vegetarian. These substances are completely removed before the wine is bottled, according to WSET, but their use means certain wines cannot be considered vegan. Bentonite, a type of clay, is one of the most popular alternatives, and PVPP is another, although as a synthetic product it is not seen as a viable option by winemakers who want their processing agents to come from natural origins. The OIV admits proteins of plant origin for fining to improve clarity, stability and gustatory properties, at a maximum usage dose of less than 50 g/hl, and its Codex monograph describes plant proteins extracted from wheat and peas. In the EU, Regulation (EU) No 1169/2011 lists eggs, fish and milk among substances causing allergies or intolerances but exempts fish gelatine or isinglass used as a fining agent in beer and wine. Regulation (EU) 2021/2117 added a nutrition declaration and a list of ingredients to the compulsory label particulars for wine, allowing the full nutrition declaration and ingredient list to be made available by electronic means without affecting the requirement that the label list substances causing allergies or intolerances; wine produced and labelled before 8 December 2023 under the earlier rules may continue to be sold until stocks are exhausted. The OIV's Code of good fining practices for casein and egg white calls for analysis to confirm that no detectable allergen residue remains, or for the product labels to reflect the presence of allergens. In Australia, the AWRI notes that casein, potassium caseinate, egg white, milk and evaporated milk must be declared on the label, while isinglass has been exempt from labelling in wine and beer since 28 May 2009.

• Animal-derived agents: egg white, casein, isinglass and gelatin
• Alternatives named by WSET: bentonite and PVPP
• EU: isinglass used as a fining agent in wine is exempt from the fish allergen listing; eggs and milk are listed allergens
• Consumer resources named by WSET: the Barnivore directory and vegan certifications such as BeVeg

The choice and dosage of fining agent both affect the outcome, since, according to the OIV, the effectiveness of a fining agent depends on the agent and the levels of addition, together with the characteristics of the wine. The AWRI advises that fining be carried out only when necessary and at lower rather than higher addition rates, as it is possible to remove positive flavour characteristics, while adding sufficient fining agent when the prime purpose is stability or removing undesirable sensory characters. Gelatine preferentially binds larger molecules, so it has a more dramatic effect on colour and tannin reduction in older wines, and excessive use of gelatine or isinglass can leave residual protein that might increase the risk of a protein haze. Excess isinglass can impart a fishy odour, excessive casein fining could impart the aroma of dairy products according to the OIV, and at high rates PVPP can result in colour and flavour stripping. Because protein-based fining agents might affect the protein stability of white wines, the AWRI advises a heat stability test after fining.

• Gelatine: the most aggressive proteinaceous agent; can easily over fine and remove colour
• Excess isinglass or casein: fishy or dairy aromas
• PVPP at high rates: colour and flavour stripping
• Best practice: conduct laboratory-scale fining trials before treating the wine in the winery, and use the smallest amount of fining agent needed to achieve the desired result

Primary sources (the Australian Wine Research Institute, the OIV, WSET and EUR-Lex): https://www.awri.com.au/industry_support/winemaking_resources/frequently_asked_questions/fining_agents/, https://www.oiv.int/standards/international-code-of-oenological-practices/part-ii-oenological-treatments-and-practices/wines/fining, https://www.oiv.int/standards/international-code-of-oenological-practices/part-ii-oenological-treatments-and-practices/wines/treatment-with-bentonites, https://www.oiv.int/standards/international-code-of-oenological-practices/part-ii-oenological-treatments-and-practices/wines/treatment-with-polyvinylpolypyrrolidone-pvpp, https://www.oiv.int/node/3642, https://www.oiv.int/node/3662, https://www.oiv.int/node/3247, https://www.wsetglobal.com/knowledge-centre/blog/2024/january/11/what-is-vegan-wine-and-how-to-find-it, https://www.wsetglobal.com/knowledge-centre/blog/2023/january/13/what-is-natural-wine, https://eur-lex.europa.eu/legal-content/EN/TXT/HTML/?uri=CELEX:32021R2117, https://eur-lex.europa.eu/legal-content/EN/TXT/HTML/?uri=CELEX:02011R1169-20180101. Last verified 2026-09-28