Beverage-grade CO₂ is the gas used to carbonate drinks and power dispense systems in bars, breweries, and soft-drink production. It is refined to meet strict industry standards, and most operators assume this makes it perfectly pure. But here’s the truth: even beverage-grade CO₂ can contain impurities that affect taste, aroma, and carbonation.
These impurities are tiny. Often measured in parts per million. But their impact is big. They can create sulphur smells, chemical aftertastes, weak fizz, and poor foam stability. Many teams spend time adjusting pressure, cleaning lines, or changing kegs, never realising the CO₂ itself is the real cause of the problem.
Beverage-grade CO₂ matters because it goes directly into the drink. It controls how well a beer holds its head, how a soft drink sparkles, and how consistent every pour feels. When the gas is clean, drinks taste bright and fresh. When the gas carries contaminants, quality drops fast.
Understanding what beverage-grade CO₂ truly means – and where its limits are – is essential for protecting the flavour, appearance, and reliability of every drink you serve.
What Does ‘Beverage-Grade CO₂’ Actually Mean?
Beverage-grade CO₂ is carbon dioxide that meets specific purity standards for use in drinks. It is intended to be clean, neutral, and safe for direct contact with beverages. But while it follows industry guidelines, it is not flawless — and understanding what those guidelines cover helps explain why issues still appear in real-world dispense systems.
Definition and Industry Use
Beverage-grade CO₂ is purified carbon dioxide that meets agreed limits for chemical and physical impurities. It is used anywhere carbonation or dispense pressure is needed, including:
- Breweries and taprooms
- Bars, pubs, and restaurants
- Fast-food beverage dispensers
- Soft drink production plants
- Cider and sparkling wine production
In all of these environments, CO₂ plays a direct role in taste, aroma, carbonation, and foam. This makes purity far more important than it is for industrial applications such as welding or refrigeration.
How Beverage-Grade CO₂ Is Produced
The journey from raw CO₂ to beverage-grade gas includes several stages. Each is designed to remove contaminants, but none can guarantee complete purity:
- CO₂ capture: CO₂ is taken from fermentation, combustion, or industrial processes. This stage alone can introduce sulphur compounds, hydrocarbons, and oxygen.
- Refining and purification: The gas is scrubbed to reduce unwanted chemicals, but trace amounts often remain.
- Compression: CO₂ is compressed into tanks and cylinders. Lubricants, oil droplets, and moisture can enter the gas stream at this point.
- Cylinder filling and transport: Contamination may occur during storage, transfer, or refilling, depending on equipment age, cleaning routines, and handling conditions.
Each step improves purity. Yet each step also carries a risk of contamination. This is why beverage-grade gas delivered by suppliers can still cause sensory faults in drinks.
Why Purity Levels Matter for Flavour, Foam, and Carbonation
Carbon dioxide isn’t just a propellant; it becomes part of the drink. It affects:
- Flavour: Impurities like hydrogen sulphide create sulphur notes, while hydrocarbons introduce plastic or chemical tastes.
- Aroma: COS (carbonyl sulphide) can give drinks a burnt or harsh smell.
- Carbonation: Contaminants weaken gas absorption, leading to flat or inconsistent fizz.
- Foam performance: In beer, impurities destabilise head formation and reduce retention.
Beverage CO₂ must meet higher standards than industrial gas because the consequences of impurities are sensory, not just operational. Customers taste the difference immediately.
This is why many bars, breweries, and producers now go beyond “beverage-grade” and polish their CO₂ at the point of use – ensuring the gas entering their drinks is truly clean.
Beverage-Grade CO₂ Standards Explained (ISBT & EIGA)
Beverage-grade CO₂ is regulated by strict industry standards, but these standards are often misunderstood. They set limits, not absolutes. Gas suppliers only need to keep contaminants below certain thresholds. Not eliminate them completely. This means compliant CO₂ can still carry compounds that affect taste, aroma, and carbonation once it reaches your drinks.
ISBT CO₂ Purity Guidelines
The International Society of Beverage Technologists (ISBT) sets global purity limits for beverage CO₂. These limits define the maximum amounts of common contaminants allowed in beverage applications:
- Carbonyl sulphide (COS): small trace amounts permitted
- Hydrogen sulphide (H₂S): detectable at very low concentrations
- Hydrocarbons: allowed in small quantities, depending on type
- Moisture levels: capped to prevent corrosion and microbial risk
These limits are designed for safety and general quality – not the ultra-clean gas needed for consistent flavour and carbonation stability.
EIGA Quality Framework
The European Industrial Gases Association (EIGA) provides a European-focused standard for CO₂ used in food and beverages. It aligns with ISBT but focuses more on production consistency, equipment cleanliness, and batch testing.
EIGA compliance ensures the gas is safe, but it does not guarantee it will be flavour neutral or sensory neutral when used in beer, cider, or soft drinks.
The Key Issue – These Standards Still Allow Contaminants
Both ISBT and EIGA standards permit trace levels of COS, H₂S, hydrocarbons, and moisture. These levels are low enough to pass compliance testing — but still high enough to create noticeable faults in real-world beverage systems.
This is why drinks can smell sulphurous, taste slightly chemical, or lose carbonation quickly even when the CO₂ is technically “beverage grade.”
Compliance doesn’t mean complete purity. It means “within limits.”
The Contaminants Found in Beverage-Grade CO₂
Even after purification, CO₂ can contain microscopic contaminants. These compounds often slip through the supply chain unnoticed – from production to transport to cylinder filling. They hide in the gas until the moment they enter your drink, where their sensory impact becomes obvious.
Hydrogen Sulphide (H₂S)
Hydrogen sulphide has a sharp sulphur smell, often compared to rotten eggs. Even tiny amounts overpower delicate aromas, especially in beer and sparkling beverages. Drinks pick up an unpleasant, sulphurous character that customers detect immediately.
Carbonyl Sulphide (COS)
COS is one of the most problematic contaminants because it is hard to remove and extremely potent. It creates burnt, chemical, or “matchstick-like” flavours that sit on top of the drink’s natural profile. Many bars and breweries unknowingly serve COS-contaminated beverages until filtration reveals the cause.
Aromatic Hydrocarbons
These compounds produce plastic, oily, or solvent-like aftertastes. They often enter CO₂ during compression or storage. Even at low levels, hydrocarbons distort flavour and make drinks taste “off” or artificial.
Moisture, Oxygen & Particulates
Moisture and oxygen are common contaminants with several effects:
- They reduce carbonation stability
- They weaken foam in beer
- They accelerate staling and oxidation
- They disrupt pressure control during dispense
Why These Contaminants Pass Through Supply Chains Unnoticed
CO₂ moves through a long, complex chain before it reaches your system. At every stage — capture, refining, transport, filling — contaminants can re-enter the gas. Most are too small to detect visually and too subtle to trigger supplier alarms. They only become obvious when drinks start:
- Tasting strange
- Losing fizz early
- Smelling chemical or sulphurous
- Pouring inconsistently
This is why beverage-grade CO₂ should always be polished at the point of use before it enters your drinks.
Why Beverage-Grade CO₂ Isn’t Always Enough
Beverage-grade CO₂ sounds like the highest standard – but in practice, it is only a minimum baseline. It guarantees safety, not sensory perfection. That means your drinks can still taste flat, harsh, or inconsistent even when your gas meets industry specifications.
Compliant CO₂ Can Still Cause Sensory Problems
Because ISBT and EIGA standards allow small amounts of COS, H₂S, hydrocarbons, and moisture, compliant CO₂ can easily create noticeable faults. These include:
- Flat beer: impurities interfere with CO₂ absorption, reducing fizz.
- Harsh aroma: sulphur compounds or hydrocarbons mask natural aromas.
- Poor foam retention: contaminants break down the proteins that stabilise beer foam.
- Chemical or plastic aftertaste: often caused by hydrocarbons or COS.
Many operators only realise the issue is CO₂ after weeks of troubleshooting pressure, lines, and cellars.
Gas Purity Degrades During Transport and Storage
Even if CO₂ leaves the production facility clean, it can pick up contaminants along the way. Purity can degrade during:
- Tanker transport: moisture, oil, or rust may enter through connections.
- Pipeline transfers: older or poorly maintained pipes can shed particulates.
- Cylinder filling: lubricants, residues, and environmental contaminants can enter cylinders.
The longer the supply chain, the higher the risk of contamination.
Why Bars and Breweries Experience CO₂-Related Issues – Even with Certified Gas
Breweries, bars, and soft-drink venues often assume their CO₂ is perfect because it arrives with a certificate. But certificates only show what was tested at the supplier, not what actually reaches your drink.
Real-world systems introduce real-world variables:
- Heat changes cylinder pressure.
- Moisture builds inside fittings.
- Regulators degrade over time.
- Storage conditions vary.
By the time CO₂ reaches your tap or tank, it may no longer meet the standard written on the certificate.
How to Ensure Clean CO₂ at the Point of Use
The best way to guarantee CO₂ purity is to clean the gas right before it enters your beverage system. This removes the contaminants that slip through capture, refining, transport, and cylinder filling.
Install a CO₂ Polishing Filter (Carboguard Mini / Carboguard Craft)
CO₂ polishing filters are the most effective way to remove trace impurities. Sure Purity’s Carboguard systems target the contaminants that cause real sensory and carbonation problems.
Carboguard removes:
- COS (carbonyl sulphide)
- H₂S (hydrogen sulphide)
- Hydrocarbons
- Moisture and trace oils
Key benefits include:
- More stable carbonation
- Cleaner flavour and aroma
- Better beer foam retention
- Consistent pours across every keg or BIB
Carboguard Mini is ideal for dispense systems (bars, pubs, fast-food chains). Carboguard Craft is engineered for breweries and production environments.
Test CO₂ Quality Regularly
Routine testing helps identify contamination early.
Options include:
- Portable CO₂ purity analysers for quick on-site checks
- Laboratory gas chromatography for detailed impurity analysis
Test after:
- Supplier changes
- Cylinder deliveries
- System maintenance
- Unexpected flavour or carbonation issues
Maintain a Clean Gas System
Even polished CO₂ needs a clean delivery pathway. Focus on:
- Moisture-free fittings
- Clean, dry regulators
- Proper cylinder storage (upright, cool, dry)
- Regular leak checks
- Replacing worn seals and washers
A clean gas system supports gas purity and stabilises carbonation.
Benefits of Using Clean, Polished CO₂
Cleaning CO₂ at the point of use delivers clear, measurable improvements across every drink you serve. When impurities are removed, carbonation becomes more stable, flavour stays true to the product, and pours become far more consistent. These benefits directly impact quality, customer satisfaction, and operational performance.
Better Taste and Aroma
Clean CO₂ preserves the natural flavours and aromas of beer, soft drinks, and sparkling beverages. With no sulphur compounds, hydrocarbons, or chemical residues entering the drink, the sensory profile remains bright, fresh, and balanced. Customers notice the difference immediately.
Stronger, Longer-Lasting Carbonation
Purified CO₂ absorbs more effectively into the liquid and stays in solution longer. This leads to:
- Livelier sparkle
- Better mouthfeel
- Improved carbonation retention from first pour to last
Clean gas allows each drink to hold its fizz as intended.
Improved Foam Retention in Beer
Foam stability depends on CO₂ quality. Impurities break down the proteins responsible for head formation, causing beer to pour flat or lose its head quickly. Polished CO₂ supports:
- Tighter bubbles
- Longer-lasting foam
- Better aroma delivery
This is especially important for premium and cask-influenced styles.
Reduced Waste
Drinks that taste off or pour flat are often discarded. Poor-quality CO₂ increases waste, increases costs, and slows service. Clean CO₂ reduces reject pours, prevents unnecessary keg changes, and delivers more consistent results.
Consistent Quality
With impurities removed, CO₂ behaves the same in every pour. This predictability protects:
- Carbonation levels
- Flavour stability
- Production consistency
- Dispense system performance
Customers enjoy the same high-quality drink every time.
Fewer Complaints
Most consumer complaints stem from flavour, aroma, foam, or carbonation issues – all of which can be caused by contaminated CO₂. Cleaning the gas eliminates these faults and reduces service issues at the bar.
Lower Operational Issues
Clean CO₂ protects equipment as well as drinks. Removing moisture and particulates reduces regulator wear, prevents line blockages, and stabilises pressure. This cuts downtime and lowers long-term maintenance costs.
Final Thoughts
Beverage-grade CO₂ is a baseline, not a guarantee. While it meets industry standards, it still contains impurities that affect taste, aroma, foam, and carbonation. Removing contaminants before the CO₂ reaches your beverage system protects quality from source to serve. It ensures the final drink reflects the flavour and freshness intended by the brewer or brand.
Explore how Sure Purity’s Carboguard systems transform beverage-grade CO₂ into clean, consistent gas that protects your drink quality from source to serve. Contact us today.
