When it comes to CO₂ recovery, the quality of the CO₂ and the impact this can have on your beer, there is much to learn. Thankfully Lenzie Kinyon, Professional Brewing Consultant and Dalum Consultant is on hand to explain more.

An increasing number of breweries are investing in CO₂ recovery technology, both in North America and around the world. Rising costs for liquid CO₂, along with recent availability issues, have drawn serious attention to the importance of collecting and using CO₂ from their own fermentation process.

Much of the success in the craft brewing industry is related to producing artisan products that stand out from the many products brewed by the major breweries, which often have similar characteristics.

By combining exceptional ingredients and their unique brewing processes, craft brewers offer beers and ales with flavours and aromas that please customers who are looking for something special. With this hands-on experience and knowledge, craft brewers are highly skilled at sourcing ingredients.

While this depth of knowledge applies to ingredients like malt and hops, this is not always true for CO₂. Craft brewers certainly know how to manage carbonation levels in their products to complement the flavours and aromas they want but have not had to concern themselves with quality of CO₂ until they started researching recovering their own CO₂ – and it might come as a bit of surprise but not all CO₂ supply is created equal.

It is imperative that craft brewers understand that when recovering CO₂, they need ensure the system or technology they are considering can achieve beverage-grade CO₂ so that their new recovered supply doesn’t contaminate the beer being produced and impact their ability to deliver a desired product to their patrons.

By moving away from purchased CO₂, brewers are giving up the purification that is part of the commercial CO₂ manufacturing process. Purification must now be done by the new recovery system being purchased. Liquid CO₂ from that system must be pure enough to carbonate without adding unwanted flavours and aromas.

The purity claims made by various recovery system suppliers should be compared to the purity recommendations for food and beverage use gases that are published by one or more industrial gas groups. These include:

• ISBT – International Society of Beverage Technologists
• EIGA – European Industrial Gas Association
• CGA – Compressed Gas Association

Brewery raw CO₂ contains many organic compounds naturally formed during fermentation. These compounds include mercaptans, esters, aldehydes, sulfides, alcohols, and other fermentation products, including oxygen that is in the headspace of each fermenter.

Unless these compounds are removed by the recovery system, they may pass through and become defects in the flavour and aroma of the brewery products they come in contact with.

The chart provided here demonstrates the profile of the gas from fermentation at a brewery that has installed a Dalum CO₂ Recovery Unit. On the left is the raw gas from fermentation coming into the CO₂ recovery plant – as you move right you can see the non-CO₂ components being eliminated as the purification and condensation process progresses. The stages include a water scrubber, compressor, dehydrator, and condenser.

The result is CO₂ purity of 99.985%–99.995% pure. While higher than ISBT benchmark meaning it’s high enough purity to use in beer, soda etc. Dalum had a customer who tested both their CO₂ from a commercial source and the CO₂ from their recovery unit and the recovered CO₂ actually tested at a higher purity which is reassuring for brewers exploring this technology.

It’s difficult to appreciate the purity without understanding the risks associated with unwanted “contaminants” from CO₂. Risks of ‘contaminated’ CO₂ include:

Risks of Contaminated CO₂

• Contaminants and Off-Flavours: The introduction of contaminants can spoil the taste and aroma of the beer. CO₂ can contain impurities like sulphur compounds, hydrocarbons, or even small amounts of other gases that, if present in the brewing process, can lead to off-flavours. Sulphur compounds, for example, can impart an unpleasant rotten-egg aroma, while hydrocarbons can give the beer a plastic-like taste. Even small levels of contamination can have a noticeable impact, leading to flavour defects that diminish the overall quality of the beer.
• Preserving Freshness and Shelf Life: The quality of CO₂ also affects the beer’s shelf life. Contaminated CO₂ can interact with compounds in the beer, leading to chemical reactions that accelerate spoilage. For example, oxygen contamination in CO₂ can cause oxidation, which gives beer stale or cardboard-like flavours.
• Inconsistent Carbonation Levels: If CO₂ levels fluctuate due to poor quality or impurities, it can result in over-carbonated or under-carbonated beer, both of which negatively affect the drinking experience. High-quality CO₂ allows brewers to achieve precise carbonation levels across all batches.
• Change in Mouthfeel and Drinkability: Using high-quality CO₂ ensures that the carbonation process goes as intended, allowing brewers to achieve the perfect mouthfeel for each style. Poor-quality CO₂ can create overly sharp or flat sensations that detract from the drinkability of the beer.

Once craft brewers start recovering their own high-quality CO₂ they are usually quite proud to tell their customers that the CO₂ used is derived from their local natural fermentation process and not trucked in from industrial sources such as a by-product from a fertiliser factory, ammonia production and ethanol.

Recovery equipment requires special engineering and complex systems to remove most or all of these unwanted compounds and until recently there were no solutions for craft breweries like this patented system from Dalum Beverage Equipment.

Large industrial manufacturing companies such as Pentair support the industrial breweries, but these units are scaled much too large for your average craft brewery and not financially feasible.

CO₂ recovery system suppliers should supply potential customers with sample analyses from actual installations they have installed at craft breweries. They should also perform start-up testing to demonstrate that the recovery system is producing high-quality CO₂. Without these assurances, the reputation of the craft brewery is on the line.