PVPP (Polyvinylpolypyrrolidone) — Color and Bitterness Fining

PVPP is a synthetic, insoluble cross-linked polymer of N-vinyl-2-pyrrolidone units, manufactured by polymerisation in the presence of catalysts such as sodium hydroxide or N,N-divinylimidazolidone. The resulting material is a light, white to cream-coloured powder that is insoluble in water, alcohol, acid, and organic solvents. Its cross-linked structure creates a large internal surface area that gives it a high capacity for adsorbing haze-forming and browning polyphenols. The polymer is food-grade and has been included in pharmacopoeias worldwide, reflecting its established safety profile as an excipient.

• Insoluble in water, organic solvents, strong mineral acids, and alkalis; remains physically distinct in wine throughout treatment
• Classified as a synthetic polymer or polyamide fining agent, distinct from protein-based finings such as gelatine, casein, and isinglass
• Available as a fine powder for single-use application or in granulated form; some grades can be regenerated and reused
• Approved by the OIV and listed as an authorised oenological compound in EU Regulation No 2019/934

PVPP removes browning compounds and bitter phenolics through selective adsorption rather than precipitation. The binding mechanism relies on hydrogen bonding between the carbonyl group of PVPP and the hydroxyl groups of polyphenolic compounds. PVPP is particularly effective at capturing low-molecular-weight phenolics, specifically monomeric and dimeric flavans such as catechin and epicatechin, flavonols, and certain anthocyanins, while larger polymeric tannins show weaker affinity. Research has shown that PVPP fining significantly modifies the aromatic profile of wine, with some aroma compounds also adsorbed through hydrophobic interactions, so dosing should be carefully managed.

• Adsorption targets monomeric and dimeric phenolics, including catechins, epicatechin, flavonols, and some anthocyanin fractions, especially coumaroylated anthocyanins
• Flavonols and flavanols show the strongest specific affinity for PVPP; anthocyanins as a class are adsorbed to a lesser overall degree
• Binding efficiency is pH-dependent; adsorption is most effective at low pH, consistent with the acidic environment of wine
• Research confirms PVPP also removes resveratrol alongside undesirable phenolics, a consideration for producers focused on wine's antioxidant profile

When correctly applied and removed, PVPP improves wine clarity and reduces bitterness and browning without introducing extraneous flavours. In white wines, it counteracts oxidative yellowing and brown tones by removing the low-molecular-weight polyphenols responsible for enzymatic and oxidative colour change. In rosé wines, it can modulate colour intensity and improve hue stability. Winemakers should be aware that PVPP treatment does modify the aromatic profile: research on Viognier and other whites shows that both pre- and post-fermentation PVPP fining alter volatile compound concentrations compared to untreated controls, so minimum effective doses and bench trials are essential.

• Reduces browning and pinking in white and rosé wines by removing oxidisable low-molecular-weight phenolics
• Reduces bitterness and astringency in both white and red wines through selective removal of monomeric and small polymeric phenols
• Can alter the aromatic profile of wine, particularly thiol aroma compounds, making bench trials critical before full-tank treatment
• Does not bind proteins, so it does not cause protein haze or strip wine body in the way that protein-active finings can

PVPP is used preventatively on juice or must before fermentation to limit oxidative phenolic load, and curatively on finished wine to address existing browning, bitterness, or pinking. It is commonly applied to white and rosé wines, and occasionally to young reds where bitterness reduction is the goal. The agent is frequently combined with casein or other protein-based finings to achieve broader phenolic and colour management. Its use is widely accepted in conventional winemaking across major producing countries, though it is forbidden for certified organic wine in the EU due to its classification as a synthetic microplastic.

• Used preventatively at the juice or must stage to limit browning potential before and during fermentation
• Applied curatively in wine to treat existing oxidative browning, bitterness, or pinking phenomena
• Frequently combined with casein or potassium caseinate for comprehensive oxidation treatment in white and rosé wines
• Prohibited in EU-certified organic winemaking; not suitable for producers seeking organic or biodynamic certification

Dosing ranges from 10–20 g/hL for preventive treatment up to 20–60 g/hL for curative applications, with a maximum legal rate of 80 g/hL under OIV and EU regulations. Bench trials on representative wine samples at multiple dose levels are essential before any full-tank treatment, as the right dose varies with vintage, grape variety, oxygen exposure history, and the degree of existing browning or bitterness. PVPP should be pre-hydrated in cool water at approximately 20 times its weight and allowed to stand for at least one hour before addition. After a contact time of several days to up to two weeks depending on the product and wine, PVPP must be removed by filtration, such as kieselguhr depth filtration, as it is insoluble and will not dissolve into the finished wine.

• Pre-hydrate PVPP in approximately 20 times its weight of cool water and allow to stand for at least one hour before adding to wine or juice
• Bench trials are non-negotiable: dose levels should be evaluated at several rates before committing to a full-tank addition
• Contact time varies by product and formulation, ranging from a few days to two weeks; follow the manufacturer specifications
• PVPP must be removed by filtration, such as kieselguhr depth filtration; in the USA, TTB regulations require filtration for PVPP removal

PVPP's classification as a synthetic microplastic has become a growing concern within the wine industry. Once washed to wastewater treatment plants, used PVPP carries significant quantities of adsorbed polyphenols and adds to microplastic pollution. Global PVPP use in the wine industry was estimated at over 1,000 tonnes in 2014, with Portugal alone using nearly 147 tonnes for white wine fining in 2016. Research has shown that PVPP can be regenerated using an ammoniacal ethanol solution and reused at least four times without loss of fining performance. Several suppliers, including Laffort, now offer PVPP-free alternatives based on plant proteins, inactivated yeasts, and bentonite combinations designed to match PVPP's phenolic removal capability.

• Global PVPP use in wine was estimated at over 1,000 tonnes in 2014; disposal into wastewater is a documented environmental concern
• PVPP can be regenerated using alkaline ethanol solutions and reused at least four times without significant loss of fining performance
• Plant-based alternatives combining vegetable proteins, inactivated yeasts, and bentonite are now commercially available as PVPP substitutes
• Winemakers seeking organic or biodynamic certification must avoid PVPP entirely, as it is excluded from approved inputs under EU organic wine regulations