There’s a scene from the movie Fight Club that has been scorched into my memory; Brad Pitt’s character, Tyler Durden, pours a very alkaline chemical on the hand of the unnamed protagonist played by Edward Norton. Soon after, a burn begins to develop on Norton’s hand until Durden pours vinegar on the developing wound to neutralize the reaction.

When I worked in a quality lab, I would perform air tests using a strong alkaline solution containing sodium hydroxide (NaOH). I never performed this test without chemical resistant gloves and protective goggles, but before I learned to wear longer cuffed gloves the solution would trickle down my arm and I wouldn’t realize it until a painful burn gradually developed on my skin. The gruesome scene from Fight Club always pops in my memory every time I think of this.

One definition of the word “caustic” is the ability to burn or corrode organic tissue through chemical action. This is because caustic liquefies fats, proteins, yeast, and bacteria, allowing these organic materials to rinse away easily with water. When a caustic chemical encounters oil and fats, it results in a process known as saponification. Saponification is the conversion of fats to fatty acid salts, or, simply, soap. Many household products contain caustic chemicals because of their power to break down organic substances, such as a clog in your shower or the bacon grease someone unfortunately dumped in the kitchen sink.

Sodium hydroxide (NaOH), sometimes referred to as “lye” or “caustic soda,” and potassium hydroxide (KOH), sometimes referred to as “potash,” are two examples of caustic chemicals. Beer line cleaning solutions often employ one of these chemicals or a combination of the two. These active ingredients are often accompanied by a surfactant which reduces the chemical’s surface tension, aids in cleaning, and improves the ability to be rinsed away.

Cleaning Recommendations Explained

When draught system hygiene is neglected, customers will begin to notice foul tasting beer, and the beer won’t pour from the tap properly. Beer naturally contains—and can harbor—a menagerie of organic substances including yeast, protein, and bacteria. Microorganisms in a draught system can form a symbiotic community where they attach to one another and draught system surfaces, and form a slimy matrix known as a biofilm. Biofilms will show up on couplers, in foam on beer detectors (FOBs), faucets, and within the beer lines themselves. This microbe party begins to organize as soon as a brand new draught system is installed and the beer begins to flow.

Biofilms are extremely difficult to remove. Not every cleaner is up for the job. Due to the organic nature of biofilms, using a powerful caustic chemical will break down this matrix, dissolving proteins, carbohydrates, and hop resins, and killing bacteria, molds, and yeast. The longer a biofilm remains on a surface, however, the more difficult it is to remove. This is why it’s recommended to clean beer lines and hardware at a minimum of once every two weeks. I always think about my bathtub and how if I cleaned it every week the job would take 10 minutes. If I get a little lazy though and let a couple of weeks pass, that same job takes significantly more time and a lot more elbow grease.

Learn more about biofilms from the expert, Dr. Darla Goeres, in Battling Biofilms in Beer Draught Lines.

Sanitizers and Acids

There are beer line cleaning chemicals that do not use sodium hydroxide or potassium hydroxide. Sanitizers work well at killing certain germs on surfaces that can be cleaned and sanitized multiple times a day, but aren’t as effective at dissolving biofilms. We sanitize glassware in restaurants every single time a customer returns a glass. There’s less opportunity for biofilms to form because not much time passes between a glass being filled, emptied, and cleaned. In a draught system, however, microbes remain in the lines for an extended period of time, allowing them time to form biofilms which will require a more powerful cleaning chemical, such as caustic.

Acids are recommended to use in a draught system cleaning regimen every three months to descale the system of beerstone, which is a substance comprised of calcium oxalate (CaC₂O₄), is not organic, not carbon containing, and therefore needs a different type of chemical for removal. For instance, some beer line chemicals contain ethylenediaminetetraacetic acid (EDTA), which binds metal ions and helps prevent the buildup of beerstone.

Evaluate Chemicals for Effectiveness and Safety

Many new technologies claim to be just as effective—or more effective—than caustic at cleaning beer lines, and I’m not ruling out this possibility. Caustic based beer line cleaners have been used and tested for efficacy and have stood the test of time. We know that it works. Other chemistries and technologies should be backed by multiple third-party lab studies to prove their effectiveness and safety. These studies need to prove that the new chemistry can break down an intricate biofilm matrix (which forms on a variety of beer tubing materials and hardware), as well as demonstrate minimal impact on the various draught system materials and metals. If the alternative cleaning system is one that is permanently installed and constantly running, such as a sonic cleaning device, there should be unbiased research to prove its ability to prevent biofilms from forming and growing as the system remains in place overtime. Most retailers I know aren’t in the habit of replacing their draught system every five years, so it’s important to know that a permanent device continues to do its job as the system ages. I’ll quote another favorite movie of mine when I think about biofilms. It’s from Jurassic Park when Dr. Ian Malcolm says, “Life finds a way.”

Caustic-based line cleaners are recommended in draught beer line cleaning practices by the Brewers Association because they are proven to break down biofilms, kill beer spoiling microbes, and injury is preventable with a few safety precautions. If you’re considering using another chemistry or technology, or you already do, my only advice is to get as much information as possible from the manufacturer. Make your decision based on unbiased scientific studies rather than testimonials or independent studies conducted by the manufacturer themselves. Safety should be a factor when evaluating new cleaning chemicals. Regardless of the line cleaning chemistry used, caustic or non-caustic, employees handling chemicals should be aware of hazards and be armed with proper personal protective equipment (PPE). Taking the time to carefully evaluate the performance of cleaning chemicals will benefit your brand reputation and bottom line, and so too will putting the same effort into ensuring you are protecting the wellbeing of yourself, staff, and customers by taking all the proper safety precautions.

Draught Beer Training Resources

• Download a free copy of the Draught Beer Quality Manual for all things draught beer
• Training for Front-of-House: Draught Line Safety for Adjacent Workers
• Training for Professional Line Cleaners: Draught Line Safety for Line Cleaners