Chitosan in Winemaking: From Clarification to Microbial Control in a Cleaner Glass

A spectrum of wines on barrel, symbolising how chitosan helps keep every style, from pale to deeply coloured, clear, stable, and microbiologically clean in the cellar.

Introduction

Modern winemaking faces mounting pressure: consumers demand wines with lower sulphite additions, production must remain sustainable, and stability cannot be compromised. The industry is acutely aware that traditional preservation methods, whilst effective, increasingly conflict with contemporary preferences for "natural," "vegan," or "minimal intervention" wines. Yet quality and shelf-life remain non-negotiable. This paradox has driven winemakers to seek complementary tools—and chitosan has emerged from niche to mainstream status.

Chitosan, a naturally derived biopolymer derived from chitin deacetylation, offers a multifunctional solution that addresses several of these tensions simultaneously. Since its approval by the International Organisation of Vine and Wine (OIV) in 2009, chitosan has moved from experimental practice to established oenological technique. It is not a replacement for existing methods, but rather a precision tool that enables winemakers to lower sulphite dependency, manage spoilage microorganisms more effectively, improve sensory clarity, and respond to sustainability imperatives—all whilst maintaining the integrity of their wine.

This article provides a comprehensive overview of chitosan in modern winemaking: what it is, how it works, where it is approved for use, what the science demonstrates, and how Entoplast is positioned as a partner in harnessing this biopolymer for the future of oenology.

What Is Chitosan and Where Does It Come From?

Chitin and Chitosan: Fundamentals

Black soldier fly: an emerging circular source of chitin and chitosan, turning organic waste into high‑value biomaterials that could one day support more sustainable oenological applications.

Chitin is a structural polysaccharide found abundantly in nature—primarily in the exoskeletons of crustaceans, the cell walls of fungi, and increasingly in the cuticles of insects. Chitosan is produced by partial deacetylation of chitin, a chemical process that removes acetyl groups and imparts a positive charge to the polymer backbone. This cationic character is the key to much of chitosan's functionality in wine.

For oenological applications, this positive charge enables chitosan to interact with negatively charged molecules (proteins, phenolics, microbes) and to chelate metal cations—properties that drive its multiple uses in the cellar.

Sources of Oenological Chitosan

Fungal Chitosan (Primary Approved Source)

Chitosan derived from Aspergillus niger fungus is the industry standard and is the source approved by OIV (OIV, 2009) and accepted as generally recognised as safe (GRAS) by the US FDA (US FDA, 2011). Fungal chitosan offers consistent purity, a precisely controlled molecular weight and degree of deacetylation, and critically, avoids the crustacean tropomyosin allergen that can contaminate shell-derived sources (Miot-Sertier et al., 2022). A subsidiary option, chitosan from Agaricus bisporus (button mushroom), has also gained GRAS recognition (US FDA, 2022) and is used in some commercial products.

Crustacean Chitosan

Traditionally extracted from shrimp, crab, and prawn processing waste, crustacean-derived chitosan is cost-effective and abundant. However, allergen risk—specifically residual tropomyosin—has driven much of the wine industry toward fungal sources, especially in markets with strict allergen labelling requirements (Amaral et al., cited in Triunfo et al., 2023).

Emerging Sources: Insect-Derived Chitosan

Chitosan from black soldier fly larvae (BSF) represents a frontier in sustainable sourcing, converting organic waste into high-value biopolymers. Recent research (Tafi et al., 2025) demonstrates that insect-derived chitosan can match or exceed the antimicrobial efficacy of fungal and crustacean sources. However, regulatory approval for wine applications remains under development. Entoplast is actively advancing BSF-derived chitosan as a future option for oenology, exemplifying how the supply base can become more circular and resilient.

Key Properties Relevant to Winemaking

• Cationic charge: Interacts with negatively charged colloids and microbes

• Chelating capacity: Binds metal ions (Fe, Cu) that promote oxidation

• Film-forming ability: Creates physical barriers against microbial ingress

• Antioxidant activity: Scavenges radicals and reduces browning

• Biodegradability: Non-synthetic, aligns with naturalness narratives

Clarification, Fining, and Haze Control

Mechanism of Action

Chitosan acts as a fining and clarification agent through electrostatic interactions. The cationic polymer binds to negatively charged colloids—proteins, polysaccharides, and tannins—forming flocs that settle or sediment, leaving clear wine above. This mechanism differs fundamentally from protein-based fining agents (gelatine, egg white) or mineral adsorbents (bentonite, PVPP), offering both distinct advantages and complementary applications.

Use Cases in Practice

A clear glass of red wine alongside fresh grapes, illustrating how chitosan fining helps winemakers turn sound fruit into bright, stable wines with reduced haze and improved clarity.

Chitosan is effective for clarifying both must (pre-fermentation) and wine (post-fermentation), addressing hazes caused by protein precipitation, unstable polysaccharides, and colloidal matter. In white and rosé wines, where colour preservation is critical, chitosan typically provides good clarification with minimal colour loss—an advantage over bentonite, which can strip aromatic compounds and reduce vibrancy (Chinnici et al., 2014).

Miot-Sertier et al. (2022) demonstrated that fungal chitosan at typical dosages (4–20 g/hL) achieves effective fining without adverse effects on wine composition, particularly in post-fermentation applications.

Comparison to Traditional Fining Agents

Unlike gelatine (animal allergen), pea protein (plant-based but variable efficacy), or PVPP (synthetic and less natural-perception friendly), chitosan is natural, vegan, and generally perceived as "clean." For producers seeking to appeal to vegan consumers or allergen-conscious markets, chitosan offers a compelling positioning.

Sensory and Quality Impacts

The scientific consensus is reassuring: chitosan fining is flavour-neutral to slightly positive in sensory outcome. Chinnici et al. (2014) found that chitosan treatment maintained varietal thiol concentrations better than control samples, contributing to fresher aromatic expression in white wines when applied at reduced sulphite levels. Colour retention in reds is typically neutral, although higher chitosan doses or prolonged contact with lees can occasionally reduce intensity slightly (Triunfo et al., 2023).

Microbial Control—Brett, Bacteria, and Beyond

The Challenge: Brettanomyces bruxellensis and Spoilage Flora

Brettanomyces bruxellensis (Brett) is the spoilage yeast that haunts winemakers, particularly those making oak-aged reds. It produces volatile phenols (4-ethylphenol, 4-ethylguaiacol) that impart earthy, leather, or medicinal off-flavours, rendering wines unmarketable. Lactic acid bacteria and wild yeasts pose subsidiary but serious risks, especially in tanks or barrels with poor sanitation. Whilst SO₂ has been the primary defence, growing consumer resistance to sulphites and emerging evidence of SO₂-resistant Brett populations have motivated alternative strategies.

Chitosan's Antimicrobial Mechanisms

Chitosan operates through multiple pathways:

• Charge-based interaction: The cationic polymer disrupts microbial cell membranes and walls, compromising integrity and nutrient transport.

• Physical adsorption and removal: Chitosan particles bind to and precipitate microbial cells, enabling their removal via racking or filtration.

• Metal chelation: By binding iron and copper, chitosan indirectly starves microbes of essential cofactors.

• Molecular weight dependency: Low-molecular-weight chitosan penetrates cells for intracellular effects (RNA, protein synthesis disruption); high-MW variants operate primarily at the cell surface (Tafi et al., 2025).

Efficacy Against Brett and Other Organisms

Petrova et al. (2016) demonstrated that chitosan preparations reduced B. bruxellensis populations from 10⁵ to 10² CFU/mL, a substantial improvement in microbial control. Tafi et al. (2025) confirmed that commercial, fungal, and insect-derived chitosan all showed antimicrobial efficacy, with insect-derived chitosan equalling or surpassing oenological-grade fungal chitosan in some strains.

Critically, Miot-Sertier et al. (2022) showed that chitosan efficacy varies by microbial species and wine conditions. Saccharomyces cerevisiae (the desired fermentation yeast) is unaffected during active fermentation, but post-fermentation spoilage organisms (non-Saccharomyces yeasts, some LAB, Brett) show significant suppression. Acetic acid bacteria show limited response and require integrated management.

Practical Application Strategy

Chitosan is used curatively (to reduce existing microbial populations) or preventively (to lower microbial load in vulnerable stages, such as post-fermentation or post-harvest). Typical doses range from 4 to 20 g/hL, applied as a treatment followed by racking to remove chitosan–microbial complexes. OIV guidelines recommend dosing ≤100 g/hL, though typical use is far lower (OIV, 2024).

Complementarity with Other Practices

Chitosan is not a substitute for hygiene or SO₂, but a powerful complement. A multi-barrier strategy—barrel sanitation, temperature control, restrained oxygen exposure, chitosan treatment, and judicious SO₂ addition—provides robust Brett prevention without escalating any single input.

Reducing SO₂ Reliance and Supporting "Cleaner" Wines

The goal of lower‑SO₂, chitosan‑supported winemaking: protecting pure fruit expression while maintaining microbiological and oxidative stability in bottle.

The Industry Shift Toward Lower Sulphites

EU regulations now permit "low sulphite" or "no added sulphites" labelling, and emerging markets increasingly reward such claims. Yet lower SO₂ increases microbial and oxidative vulnerability. The oenological challenge is to maintain stability whilst reducing chemical dependency.

Chitosan's Role in SO₂ Reduction Strategies

By suppressing microbial populations—particularly Brett—chitosan lowers the minimum free SO₂ needed to maintain a safety margin. A wine stabilised with chitosan-assisted microbial management may require free SO₂ of 20–30 mg/L rather than 40–50 mg/L, a meaningful reduction for marketing and consumer perception (Chinnici et al., 2014; Triunfo et al., 2023).

Additionally, chitosan's antioxidant and metal-chelating properties reduce the oxidative pressure that SO₂ must counteract, further enabling lower total SO₂ protocols.

Honest Positioning: Limitations

Chitosan does not substitute for SO₂'s antioxidant action. Oxygen management (headspace control, inert gas use) and possibly lower pH remain essential. Chitosan is best framed as enabling more precise, lower SO₂ regimes through additive risk reduction, not replacement.

Metal, Contaminant, and Off-Flavour Management

Metal Chelation and Oxidation Prevention

Chitosan's positively charged backbone binds ferrous and cupric ions with high affinity. Chinnici et al. (2014) demonstrated that chitosan chelated approximately 70% of added iron and 30% of copper in model solutions. This is significant: iron-catalysed oxidation is a silent threat to white wine freshness and aromatic stability. By removing "active" iron, chitosan preserves thiol compounds and extends perceived freshness.

Ochratoxin A and Other Contaminants

Ochratoxin A (OTA), a mycotoxin from Aspergillus species, contaminates grapes in some vintage conditions and is hazardous at concentration >2 μg/kg. Chitosan-based adsorbent treatments can reduce OTA in contaminated wines by 40–70%, depending on initial contamination and treatment conditions (Quintela et al., 2012; Triunfo et al., 2023). EU and OIV regulations permit chitosan and chitin–glucan for contaminant removal, recognising this validated application.

Off-Flavour Precursors

Emerging data suggest chitosan may adsorb reductive sulphur compounds (H₂S precursors) and certain off-flavour precursors, though mechanisms are not fully elucidated. Sensory and bench-trial validation remains essential before claiming off-flavour remediation.

Sparkling Wines and Lees Management

Barrels maturing sparkling and still wines, where targeted chitosan use helps manage Brett risk, refine lees behaviour, and protect long‑term stability without relying solely on higher SO₂.

Specialised Use in Traditional-Method Sparkling Wine

Chitosan additions during tirage (before the secondary fermentation) or during ageing on lees modulate yeast settling behaviour, lees compaction, and eventual clarity for riddling and disgorging. Triunfo et al. (2020) found that chitosan did not negatively affect sensory parameters (mousse, bubble character, freshness) and improved clarity post-disgorge, facilitating faster market-readiness.

Lees management is subtle: chitosan can modify yeast flocculation and polysaccharide deposition, potentially enhancing riddling efficiency and reducing sediment re-suspension during handling. However, prolonged contact with lees may modulate autolytic character, so careful monitoring is warranted.

Oxidative Stability in Bottle

The antioxidant and chelating properties mentioned earlier translate to enhanced oxidative stability in sparkling bottles, where residual oxygen and extended shelf-life present challenges. Preliminary data support improved freshness retention, though larger trials are ongoing (Triunfo et al., 2020).

Regulatory, Safety, and Labelling Framework

OIV and International Approval

The OIV, in resolutions OENO 336A-2009, 337A-2009, and 338A-2009, authorised chitosan (fungal origin) as an approved oenological practice for fining, clarification, and antimicrobial treatment of wines. Dosage is capped at ≤100 g/hL, and chitosan must comply with the International Oenological Codex specifications (OIV, 2024). EU Regulation 1169/2011 incorporates OIV guidance; the UK, post-Brexit, has adopted aligned frameworks (UK legislation, 2019).

Allergen and Labelling Considerations

Crustacean-derived chitosan carries tropomyosin (a known shellfish allergen), necessitating declaration. Fungal-origin chitosan is allergen-free and does not require specific declaration in most jurisdictions (though full transparency is always advisable). Given regulatory and market momentum toward fungal sources, the allergen issue is largely resolved.

Safety Profile

Chitosan has been designated GRAS by the US FDA for use in alcoholic beverages (US FDA, 2011, 2022). Residual chitosan levels in finished wine are minimal (typically <1 mg/L post-racking), and the biopolymer is not bio-accumulated. Safety data on acute and chronic exposure support its use at approved dosages.

Sustainability and Circular Bioeconomy

Comparative Sustainability Profile

Traditional fining agents differ widely in sustainability: gelatine requires livestock; bentonite is mined; PVPP is synthetic. Fungal chitosan valorises Aspergillus biomass (otherwise discarded in fermentation or food production), converting waste into high-value product. Crustacean chitosan similarly upcycles shellfish processing waste. Neither requires new extraction pressure on wild resources.

Insect-derived chitosan, the domain Entoplast is advancing, elevates sustainability further. Black soldier fly larvae convert organic waste (agricultural by-products, food residues) into biomass. Chitosan extraction from BSF cuticles closes a loop: waste → bioconversion → biopolymer → wine. This exemplifies circular bioeconomy principles and reduces reliance on crustacean or fungal byproducts (Tafi et al., 2025).

Alignment with "Natural" and "Clean" Wine Narratives

For organic, biodynamic, and "natural" wine producers (where regulations permit chitosan use), the biopolymer aligns well with minimalist philosophy. It is renewable, non-synthetic, and non-invasive compared to mined minerals or petro-derived compounds.

Entoplast's Strategic Position

Entoplast is advancing BSF-derived chitin and chitosan as the next-generation sustainable feedstock. Whilst fungal chitosan dominates current wine practice, Entoplast's work ensures that as regulations and market appetite for insect-derived inputs grow, the wine industry will have access to a resilient, circular, and demonstrably effective supply base. Recent research (Tafi et al., 2025) confirms BSF chitosan's antimicrobial efficacy matches or exceeds conventional sources, opening a pathway for oenological innovation grounded in sustainability.

Conclusion

Chitosan has matured from experimental additive to established oenological tool, approved by OIV, validated by peer-reviewed research, and widely adopted by forward-thinking winemakers. Its multifunctional profile is extraordinary: it clarifies wine, controls Brett and spoilage microbes, reduces the need for SO₂, chelates metals, stabilises against oxidation, and supports sustainable viticulture. Equally important, it remains sensory-neutral to positive, preserving the varietal character winemakers cherish.

The science is clear: chitosan works best as part of an integrated strategy. It is not magic, but precision. Winemakers applying chitosan succeed when they conduct bench trials, optimise dosage, monitor sensory outcomes, and combine treatment with complementary practices (hygiene, temperature control, SO₂ stewardship).

Entoplast stands at the forefront of this evolution. We supply high-quality chitosan derived from Black Soldier Flies. Our commitment is to partner with winemakers and consultants in developing tailored protocols—whether for Brett suppression in Burgundy-style reds, thiol preservation in cool-climate whites, or sparkling-wine lees management.

We invite you to:

• Explore chitosan trials for your specific wine style and production constraints.

• Engage with our technical team on application guidelines and dosage optimisation.

• Join us in advancing sustainable chitosan sourcing as part of a cleaner, more resilient wine future.

  
  

The glass is indeed cleaner with chitosan. Let's make it your standard.