Sanitary Testers: ATP Theory

What is ATP and why is it used as an indicator of sanitary quality in brewing and draught beer systems?

ATP, short for “adenosine triphosphate,” is a high-energy molecule that stores energy in cells, and consists of adenine, a ribose sugar, and three phosphate groups (Timberlake, Structures of Life, 2nd ed., 2007). ATP, because of its prevalent role in cellular metabolism, is a highly ubiquitous biomolecule that is produced by nearly every living cell of every species. It is the carrier of chemical energy that fuels the majority of anabolic reactions within an organism to maintain metabolic balance.

How does cellular metabolism and ATP production relate to brewery and draught beer sanitation?

The theory applied to the use of ATP as an indicator molecule for sanitary quality is based on well-accepted scientific knowledge that every living cell must produce ATP to stay alive; therefore, ATP levels should correspond to the number of bacterial cells living in a sample of beer. But it is important to understand that electronic ATP testers are only able to detect ATP and CANNOT detect bacterial cells.

Since the development of ATP sensors for detecting bacterial levels beer, much has been learned about bacterial life cycles and the efficacy of ATP for quantitative analysis. Recent biochemical and microbiological research has indicated that ATP levels do vary with cell count, but population size is not the primary determinant of ATP levels. ATP concentration varies depending on a number of environmental factors unrelated to bacterial population size.

Factors Affecting ATP Test Results:

ATP is a nutrient. Cellular processes have evolved in ways that efficiently support life. Because ATP is critical to the health of a living organism, bacteria prefer not to export ATP out of the cell. Nearly all ATP, like any nutrient, will remain inside of the cell (intracellular) until it is digested during regular cellular metabolism and excreted as waste.

Cells of any species have enzymes and organelles that precisely orchestrate the uptake of useful chemicals and nutrients into the cell, while ensuring effective digestion and release of waste products and toxins out of the cell.

In a study performed at UCLA and Berkeley, extracellular ATP concentrations among Salmonella and E. coli test strains showed to vary from 1-30 nanomoles during growth and stationary phase, and extracellular ATP actually decreased during stationary phase—when cell count is highest (Mempin, Release of extracellular ATP during growth, BMC Microbiology, 2013).

The ATP that is detected by an ATP tester is a tiny portion of the total ATP that exists in any sample of beer. The ATP sensed by the chemical probe of an ATP tester results from extracellular ATP release which will vary independent of population size—as much as 30-fold—during the life of a bacterial colony. The great majority of ATP exists intracellularly and is not accessible to a sensor or probe. Consequently, ATP test results do not provide an accurate measurement of total ATP or the concentration of viable bacterial cells in a sample of beer.

Life Cycle

The bacterial life cycle is complex. Understanding the build-up, maintenance, and subsequent destruction of bacterial cells and colonies is obviously a very important area of scientific research. These topics involve everything from antibiotic development and public sanitation to environmental bioremediation and ecology. Microbes are everywhere, and the mysteries of their existence have been under investigation since Louis Pasteur’s discovery of single-celled organisms in 1860. Bacteria continue to evolve and scientists continue to reveal their phenomenal strategies to maintain health and reproduction.

The life cycle of a bacterial cell, like any living organism, has a natural rhythm and sequence of events—it is produced by the division of a parent cell, daughter cells undergo growth and maturation, then reproduce or die. But this ideal framework for understanding bacterial life is averted when environmental fluctuations stimulate bacterial survival strategies that drastically alter the metabolic activities and physical composition of bacterial cells and colonies.


One of the most important environmental factors that affects cellular metabolism is the availability of nutrients. Cells will oscillate between a healthy, “well-fed” state and a starvation state. These conditions direct metabolic responses from the cell involving ATP production and consumption. One of the most essential nutrients for the life of a cell is sugar.

Sugar, in the form of maltose and glucose, is also an essential ingredient in beer. Bacteria living in draught beer and brewing systems are dependent on sugar for healthy metabolism and ATP production. Glucose, specifically, is the precursor molecule for the production of ATP, therefore, when glucose levels are high, ATP production is optimized and cells grow and reproduce at a healthy sustainable rate. If nutrient availability is depleted, cells will slow their production of new ATP molecules and conserve existing ATP.

In a study of 21 different bacterial species belonging to the genus Enterococcus, nutrient-deprived cells that were unable to produce ATP due to starvation were placed in a 1% (wt/vol) glucose liquid growth agar to stimulate ATP production. The result was an immediate 5 to 30-fold increase in both intracellular and extracellular ATP within the first hour (Hironaka, Glucose Triggers ATP Secretion from Bacteria in a Growth-Phase-Dependent Manner, Applied and Environmental Microbiology, 2013).

The effect nutrient availability has on cellular processes and ATP level is quite significant, and must be taken into consideration when interpreting results of an ATP test with regard to bacterial population and sanitation.


Another effect that environmental conditions have on bacterial production of ATP is caused by the presence or absence of oxygen. Oxygen, like sugar, is essential to the health of a cell. It is the single determinant of aerobic and anaerobic metabolism. When oxygen is present in the environment, cells perform aerobically. Environmental oxygen is taken up by the cell and utilized in cellular respiration for ATP synthesis. When oxygen is available, cellular respiration occurs at a rate that yields 32 ATP molecules per 1 glucose sugar molecule.

It is standard practice in the brewing and draught beer industries, though, to implement procedures that minimize oxygen levels in beer, therefore, many of the microbes contaminating beer are likely to be undergoing anaerobic metabolism as well. Anaerobic metabolism is stimulated when oxygen levels are low. In beer, bacteria rely on fermentative anaerobic pathways for their survival. Fermentation enables cells to metabolize glucose sugar in the absence of oxygen, but yields only 2 ATP molecules per glucose molecule (Nelson, Principles of Biochemistry, 5th ed., 2008).

Depending on the level of dissolved oxygen in any beer, ATP levels will vary up to a factor of 16 between aerobic and anaerobic metabolism. Such dramatic variations in ATP levels are the effect of dissolved oxygen concentration and biochemical response by bacteria, and are not correlated to bacterial population size.


Biofilms are complex communities of bacteria living in a self-produced matrix that is capable of adhering to both inert and biological surfaces (Van Houdt, Biofilm formation and cell-to-cell signaling in Gram-negative bacteria isolated from a food processing environment, Journal of Applied Microbiology, 2003). Biofilms are a somewhat recent topic of interest to biochemists and microbiologists, as the industrial relevance of bacterial biofilms has grown to be quite significant.

Biofilms display a level of cooperative strategy among bacterial communities that is unobserved in planktonic (free-floating) bacteria. Many species of bacteria are capable of organizing communal defense mechanisms and survival strategies by forming into films. Biofilms are protected by a mucosal or polysaccharide layer that is secreted by the participating cells. This layer not only protects the colony from environmental stress, it also selectively channels chemicals throughout the microbial community to conserve essential biomolecules like ATP while efficiently transporting waste out (Wilking, Liquid transport facilitated by channels in Bacillus subtilis biofilms, National Academy of Sciences, 2012).

Once biofilms are established, they are difficult to remove and poorly detect by ATP alone. In a study performed by the American Association for Laboratory Animal Science, researchers determined the average minimum detection level for E coli to be 1,000,000 cells per milliliter, and stated that “pure gram-negative bacteria are detected very weakly” by ATP alone (Turner, Efficacy and Limitations of an ATP-Based Monitoring System, Journal of the American Association of Laboratory Animal Science, 2010).

Biofilm development among bacterial species such as E. coli is stimulated as a survival mechanism when population density escalates and nutrients become scarce. Biofilms enable large bacterial populations to persist under sub-optimal living conditions by conserving nutrients, slowing their metabolism, and constructing a protective barrier between the cells and their environment.

ATP is not released from biofilms at a significant rate and therefore should not be used to measure bacterial levels if biofilms are present. In addition, biofilms form when bacterial population size is at its peak, and will render false negative results when serious contamination may in fact be present.

Suggested Methods for Measuring Bacterial Contamination in Beer

The most effective methods for determining sanitary quality involve visualization of actual bacterial cells within a test sample of beer. This is accomplished by placing samples on solid growth media composed of sugar and other essential nutrients, and allowing bacterial colonies to grow. Each cell present in the original sample will grow into a visible colony on the media. Contamination can then be determined based on the number of CFUs (colony forming units) that grow.

This method produces a very accurate measurement of bacterial contamination, which is described in practical terms as a ratio of cells per unit volume. By producing results directly from the physical presence of living bacterial cells, the researcher eliminates the potential for instrumental error and limitations that may be incurred by using electronic test equipment.

The quantitative sensitivity of culture plate tests may also be adjusted by producing serial dilutions of the original sample or altering the volume of sample plated. A very large sample size may be tested to detect minor contamination when cell counts are very low (ie. below the detectable limit of an electronic ATP tester). If contamination is more serious, the visualization and quantification of dense bacterial populations is improved by simply diluting the original sample.

By accurately determining cell count, brewery and draught beer technicians can precisely gauge the effectiveness of their sanitation procedures. Maximum contaminant levels (MCLs) for bacteria should be set as quality control parameters to direct sanitation protocol. By implementing routine culture plate analyses, brewery laboratories and draught beer technicians can ensure proper product quality and the health and safety of their customers.

Guidelines for Using Vinyl Tubing in Draught Beer Systems

There are three locations on a tap system where it may be necessary to use vinyl tubing:

  1. Inside of direct-draw “beer boxes” where runs are six feet or less
  2. Inside of walk-in coolers as “jumper” line connecting the keg coupler to the trunk line
  3. Immediately before the beer shank and faucet as “choker” line to complete the required restriction rating for the system

Because vinyl is not considered a food grade material, the use of vinyl beer and gas lines should be kept to a minimum when designing and installing any tap system.

Vinyl tubing entered the draught beer industry as an alternative to copper and tin coils for short run direct-draw draught beer systems. The advantage is that vinyl is very flexible, unlike copper and tin, and it provides a restriction value similar to that of a copper or tin coil, therefore making it an ideal alternative to conventional coil systems.

Today, tap systems come in a variety of shapes and sizes, and the use of vinyl material has been implemented for both the added flexibility and as a convenient method of adding restriction to a system when necessary; but it must be noted that vinyl, as compared to copper, tin, and polyethylene materials, collects far more debris due to its porous, absorbent nature, and in order to maintain optimal sanitation within a tap system, the use of vinyl must be kept to an absolute minimum.   

Guidelines for Using Vinyl Tubing in Draught Beer Systems

Always use clear vinyl tubing so that contamination can be seen.

Direct-draw Systems

Direct-draw systems utilize 3/16” inner diameter (id) tubing for all beer line. The length of vinyl tubing used per line must match the desired restriction rating for the system. A standard American system dispenses beer at a carbonation rating of 2.5 – 2.7 volumes CO2 at a rate of 2 ounces per second (8 seconds per pint).

These dispense specifications are achieved only if the applied gas pressure, keg pressure, and total restriction rating of the system are each equal to 10 psi and the beer is dispensed at 35° F. Therefore, the appropriate length of each vinyl beer line may be determined by obtaining the restriction rating from the manufacturer, then dividing 10 psi by that rating. Most 3/16” id vinyl tubing has restriction ratings of 1 to 3 lbs/ft.

Example: If the rating is 2, divide 10 psi by 2 lbs/ft and the line length required to achieve 10 lbs total restriction is 5 ft.

Vinyl gas line should also be kept to a minimum. Most couplers are fitted with a 5/16” id gas inlet, so 5/16” is the practical size for gas line. One main gas line should run from the gas source to a manifold or T, and the manifold should be placed at a location that minimizes the length of gas line required to reach each coupler.

It’s necessary to keep the use of vinyl gas line to a minimum because vinyl, unlike metal and polyethylene, is gas permeable. This means that trace amounts of CO2 and N2 naturally escape through the vinyl material itself, thus incurring continuous gas loss. In order to minimize operating costs, vinyl gas line should be used sparingly.

Long-draw Systems

Long-draw systems are composed primarily of polyethylene beer line, but vinyl may be used as “choker” and “jumper” line at the front and rear of the system. Inside of a walk-in cooler, vinyl beer line may be used to connect each polyethylene line of the main beer line bundle to their respective keg couplers. For this application, 5/16″ or 3/8” id vinyl beer line is preferred. Vinyl will add a significant amount of restriction to the system; therefore, larger diameters are used in order to minimize restriction at the rear of the system.

Restriction must increase from rear to front, so that the flow of beer decelerates as it moves through the system and pressure is maintained. Remember, pressure is defined as resistance to flow. If restriction ratings decrease from rear to front, beer flow will accelerate, resulting in agitation, and pressure will be lost causing gas to separate from liquid, and subsequent foam at the faucet.

When installing vinyl jumper lines inside of a walk-in, there are three factors to consider:

  1. The height of the tap system
  2. The distance to the floor of the walk-in
  3. The restriction imparted by the addition of each piece of vinyl

Ideally, the highest point of elevation on a tap system will be the faucets. Beer in a tap system is pressure-driven, and the pressure originates at a gas source. Since gas is naturally lighter than liquid (at least in terms of CO2/N2 versus liquid beer), the gas in the system is constantly trying to rise—drawing beer with it. If at any location in a tap system the beer line peaks above the elevation of the faucets, gas will have a natural tendency to accumulate there, creating a gas pocket. When gas accumulations release, the result is “burping” or “bubbles” at the faucet.

Given an ideal setting upon installation, a tap system will be installed with the faucets being the highest point. So, when connecting vinyl jumper lines to trunk line, keep all jumper lines below the level of the faucets, as to prevent accumulation of gas within the jumper lines.

Once the upper end of each vinyl jumper line has been connected, the maximum allowable length of each line may be calculated by measuring the distance from the trunk/jumper connection to the floor, then subtracting six inches. This will provide space for the coupler to be connected without touching the floor when the jumper line is hung freely. Preventing the coupler from touching the floor is a sanitary measure that will avert microbial contamination of beer inside the keg.


Once the maximum jumper line length is determined, calculate the restriction that will be imparted based on length and inner diameter. Take this number into account, as it will be a critical figure in the overall restriction of the tap system. The restriction imparted by vinyl jumpers can be adjusted by altering the length and inner diameter of the vinyl line used.

portside-bar-walkinAlso, keep in mind that if jumpers are not all the same length, then restriction will vary line to line and equality must be re-established somewhere else in the system. Therefore, it is best to keep jumper line lengths consistent throughout the system regardless of the potential added convenience of lengthening jumper lines to reach kegs. JUMPER LINES ARE NOT EXTENSION LINES. Move the keg to the line. Do not extend the line to the keg. And keep all vinyl jumper line lengths to a minimum to ensure optimal system sanitation and to minimize gas loss.

Installing vinyl choker line is not always necessary, and most tap systems can be designed to avoid the use of choker. But if beer is pouring too fast or increased carbonation is desired, the addition of vinyl choker line is a simple and easy modification that will remedy flow rate and carbonation issues when all other factors are within specification.

By using 3/16” id vinyl tubing that has a restriction rating of 3 lbs/ft, the total restriction of a tap system can be increased without significantly increasing total line length. Choker line is placed directly behind the faucet and shank to slow pour rate and increase the volume of CO2 the system will retain.

Cleveland Beer Line Cleaning, LLC takes great pride in the customization of each tap system we install. Proper use of vinyl beer and gas line is a critical determinant in the resulting performance, sanitation, and efficiency of a draught beer system. By understanding the demands of each establishment, we are able to correctly design a system that suits our customers’ needs, and will dispense quality draught beer for years to come.

Want us to take a look at your tap system installation? Or do you need a tap system installed?

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Sensory Check Your System for Spoilage: See, Smell, Taste?

Performing sensory checks on your tap system is important for obvious reasons:

  1. To ensure the health and safety of your guests
  2. To maintain proper draught beer quality
  3. To check that your line cleaner is performing up to par.

A draught beer system that is properly maintained on a two week schedule should never fall victim to spoilage issues. But if it has been longer than 2 weeks since your system’s last cleaning, or if you feel that recent cleanings have not been fully effective, you can perform simple sensory checks on your tap system to locate sanitation trouble spots.

How to Check Your System for Spoilage

Keg Couplers and Faucets

cleveland beer line cleaning, dirty couplerThe most common points of microbial infection on a tap system are the faucets and keg couplers. These two locations are constantly exposed to open air where airborne bacteria, mold, and yeast will continually take advantage of beer as a nutrient source, forming films on sugar and protein residues that develop on these components.

If a keg coupler is infected with microbial film, it will be very visible. Simply remove the coupler from the keg and inspect for any slimy, moldy buildup around the seal and keg-coupler connection. If a microbial film is present, those microbes are certainly infecting the beer in your tap system as well, and immediate corrective action is required.

Couplers should be removed from kegs and soaked in soapy cleveland beer line cleaning, dirty couplerwater. Most of the film will fall off and the remainder may be scrubbed off using a small brush (toothbrush works well). To prevent future films from growing, couplers may be sprayed regularly with a simple antiseptic solution such as 50/50 rubbing alcohol (isopropanol)/water or 50/50 ammonia/water. These chemicals are strong antimicrobial agents that are safe to use as a no-rinse sanitizer on tap system components and will leave no flavor or aroma in the beer.

Beer faucets are of equal concern as they will spend their entire life exposed to an array of airborne pathogens and spoilage microorganisms. Faucets are made of food grade materials that inhibit the binding and growth of airborne microbes. But a poorly maintained faucet loses its antimicrobial properties when beer and foam is allowed to dry on the exterior. These dry residues are an cleveland beer line cleaning, dirty faucet residueopen invitation for microbial contamination. Airborne bacteria, mold, and yeast will quickly bind to these residues, metabolize them, and produce off-flavors and aromas at the faucet.

If there is any visible film on or in a faucet, it should be de-soiled immediately using a clean wet cloth and faucet brush. Faucets must be sanitized at the end of each shift using a simple chemical no-rinse sanitizer such as alcohol, ammonia, or an oxidizer.

To check for faucet sanitation issues, first observe the outside of the faucet for any dry beer residue and mold growth around the lever, plunger, and shank collar. Next check the inside of the faucet by rolling up a white paper napkin, inserting it into the faucet spout, then twisting and removing the napkin to see if any residue is being collected. If there is visible residue on the napkin, your faucets are in need of more frequent in-house sanitation procedures.

Next, sensory check for spoilage by smelling the napkin for a number of aromas that are often present. They are commonly described as having pungent characteristics of stinky feet, cheese, and vinegar. If you detect any of these odors, then common spoilage bacteria and yeast are present which produce acetic, lactic, and butyric acids that we associate with having these classic beer-spoilage aromas. Also, be sure to check faucet covers in the same way you checked your faucets, as these can be a site of infection (and re-infection) if not kept to the same sanitary standard as your faucets. Faucet covers should be soaked in sanitary solution when not in use and cleaned regularly using a faucet brush.

Drip Trays and Drains

Another common spoilage site is the beer drip tray and drain which are located just inches below the faucets. Your efforts to maintain clean beer faucets will be aided if a clean drip tray and drain is maintained. An infected drain will emit intense sour spoilage aromas, as well as provide a secondary site for bacteria, mold, and yeast to breed and produce future generations that will continually re-infect faucets and draught beer lines. Stale odors will be evident and residue buildup is usually visible inside the drain tube if drain cleaning has been neglected. Drip trays and drains should be flushed daily with hot water and can be stored overnight with a thick detergent inside to kill odors and prevent further microbial contamination.


Proper refrigerator hygiene is of considerable importance to the overall sanitation of a tap system. It is natural for spillage to occur in a walk-in refrigerator or beer box. It seems that every time a keg is changed some small amount of beer seems to seep out and find its way onto the floor. These tiny beer puddles aren’t even noticeable at first, but over time they will build up to create a major sanitation problem. Cold-tolerant bacteria, mold, and yeast breed on these beer residues left in refrigerators. Refrigeration will slow their growth, but it will never stop it completely.

Films of mold on refrigerator floors become especially visible if proper housekeeping procedures are not adhered to. One of the best investments for a keg cooler (other than the kegs themselves) is keg racks that hold kegs about 6 to 12 inches off the ground. This enables easy, continuous clean-up without ever having to move or lift kegs to mop under. By eliminating beer residue buildup inside keg coolers, airborne bacteria, mold, and yeast populations are significantly reduced, thus preventing these microbes from entering the lines.

Vinyl Lines

beer line cleaning, dirty vinyl beer linesIf exterior tap system components have experienced spoilage issues, then it’s likely the interior of the system contains spoilage microorganisms as well. Mold on keg couplers quickly makes its way into beer and gas lines. If your system was properly designed with clear vinyl jumper lines, then you will be able to see microbial deposits if infection is present. These deposits will appear as dark discolorations, solid films, and/or spots of microbial colonies.

You may also check for spoilage aromas in your gas lines by removing the coupler from the keg, moving the coupler handle into its down position (as if tapping a keg), and allowing for CO2 to flow from the coupler. CO2 has a refreshing aroma like the clean effervescence of mineral water. But if vinyl gas lines are contaminated, the CO2 will smell more like bad breath or a dirty locker room. Be sure to return the coupler handle to its up position to stop CO2 flow after inspection, as CO2 buildup in an enclosed area, like a refrigerator, poses a severe asphyxiation hazard.

Due to the highly porous and absorbent nature of vinyl materials, infections in vinyl lines are very difficult to remove, even with extreme chemical cleaning attempts. Tap systems are designed so that vinyl line replacement is easy and affordable. It is recommended that vinyl lines showing signs of infection be replaced immediately. By cleveland beer line cleaning, dirty fobdoing so, permanent sources of spoilage are completely removed from the system, providing a clean slate for fresh draught beer service.

If your draught beer system is equipped with foam-on-beer detectors (FOBs), this may be another site of infection. These devices are made out of plastic materials that, like vinyl, will absorb residues and off-flavors over time. These devices also create dead spots (points where flow is limited) in the system, which promotes the deposition and growth of microbial films. Check your FOBs for discoloration and film. FOBs must be removed from the system, disassembled, and scrubbed internally in order to achieve proper sanitation.

Observe the Beer

Finally, observe the aroma, flavor, body, and head retention qualities of beer served from your system. The beer itself should be the initial indicator of sanitary quality and the final confirmation of a properly maintained draught beer system.

The most profound analysis is offered in the first glass of beer poured from each line every day. This pint has sat in the line the longest and has had the greatest opportunity to pick up off-flavors and aromas. Pour this beer into a clean glass that is free of any sanitizer residue. Immediately after pouring, draw the aromatics of the first beer in through your nose focusing discretely on the malt and hop aromatic qualities. Both should be intense and uncompromised by any foul odors.

Next, set the glass down and allow the foam to settle. Clean beer served in a clean glass will maintain some head on the surface of the beer and some head will remain adhered to the interior of the glass as well.

Also, look for clarity in the body of the beer. Most filtered beer will allow light to pass through regardless of the color of malt used. A beer served from poorly maintained draught beer lines may be hazy and block light due to suspended solid sediment that is picked up within a dirty beer line. If your beer passes olfactory and visual inspection, then taste it. Bartenders and servers should be encouraged to regularly sample draught beer so that they become intuitively aware of the unique qualities of each beer, and will be able to immediately recognize spoilage issues.

Be sure to have your beer lines cleaned every two weeks, as recommended by the Brewers Association and the State of Ohio, and perform random in-house sensory checks to learn the quality of your system, the quality of the beer it is dispensing, and the quality of workmanship of the beer line cleaner you have hired.

Lastly, perform sensory checks because if you don’t, someone else will. And that person will likely be a customer (or multiple customers) who will either rave to their friends about your beer selection and the quality of service, or insist on never going back because their stout was skunky and sour.

Beer Line Cleaning Chemicals – A Breakdown

There are three distinct classes of cleaning chemicals (not just for beer lines): ions, detergents, and enzymes. Each is unique in their chemical structure, rendering them suitable for specific purposes. The major factors to consider when choosing a cleaning solution are the chemical nature of the residue that is being cleaned and the specificity of the cleaning chemical for that particular residue.

For the application of draught beer line cleaning, sugars and proteins are the major residues to be considered. Both of these chemicals exhibit varying degrees of polarity, meaning that they are molecules that carry both negative and positive charges; some are stronger than others, but all are charged nonetheless. Fats and oils, on the other hand, are nonpolar and carry no charge. Fats and oils are found in very minute concentrations in beer, whereas sugars and proteins make up the bulk of the body, flavor, and color of a beer.

Ionic Solutions

Ionic solutions include acids and bases, and are collectively called “electrolytes.” The term “caustic” is frequently used to refer to a basic solution. Ions are the smallest molecules capable of performing big cleaning tasks. Their small size is advantageous because it enables the ion to maximize contact in even the smallest pores and pockets within a contaminated beer line.

Acids utilize the incredibly strong positive charge of protons (Hydrogen ions) to disrupt the bonds and structures of other charged compounds such as proteins, sugars, and even minerals, thus denaturing them and subsequently removing them from a tap system during flushing and rinsing of the system.

The molecular mass of an ionized Hydrogen atom (H+) is 1 atomic mass unit (amu). This is literally the weight of a single proton. Bases, or caustic chemicals, work under the same chemical principle as acids, but they are negatively charged due to the addition of one oxygen atom per hydroxide (OH-) molecule. The oxygen naturally carries a strong negative charge that will disrupt other charged molecules, degrade them, and subsequently remove them from a tap system. Hydroxide molecules are slightly larger, having a mass of 17 amu, but are still very effective at penetrating molecular residues in beer lines, considering sugar and protein masses range from 180 amu to over 1,000,000 amu.

Because ions are so small and their reactivity is non-discriminatory toward polar compounds, acids and bases are capable of breaking down nearly any sugar and protein residue regardless of the size and structure of its chemical constituents.


Detergents (aka soaps, surfactants) are designed to attack both polar and nonpolar residues. In chemistry, this unique characteristic of reactivity is called “amphiphilic” – soluble in both water and oil.

Detergents are unique and very useful for certain applications. They can be mixed with water, and the solution may be used to remove sugar, protein, mineral, oil, fat, and grease residues. Detergents’ non-specificity for residues makes them a versatile cleaning compound, and they are generally very good at degreasing and removing fats and oils. Contrary to our application of draught beer line cleaning though, nonpolar fats and oils only occur in trace amounts in beer and have a low tendency to adhere and remain in beer lines.

It is true that hop oils are extracted during the brewing process for their bittering and aromatic attributes, and hops are probably the greatest contributor of oils to any beer. Grain (barley) produces a negligible amount of oil. Of course all plants produce oils – olive oil, corn oil, sunflower oil, peanut oil – but have you ever heard of barley oil? (It actually does exist and is very healthy for you as an antioxidant and source of vitamin E).

Detergents work by forming micelles in water. A micelle is an assembly of surfactant molecules which form a ball-like structure with the polar portions of the molecules on the outside in contact with water (also polar) and the nonpolar ends sequestered on the inside of the ball away from exposure to water. This enables the fatty (nonpolar) ends of the surfactant molecules to disperse throughout a water-based solution and react with other fats and oils. Micelles range in size and are generally far greater in mass than ions. Micelle sizes in terms of amu are in the 100s to 1,000s. This renders them less capable of penetrating dense residues and cleaning porous surfaces such as vinyl.


Enzymes are by far the largest molecules used for cleaning, ranging from about 50,000 amu to well over 100,000 amu. They are also exquisitely specific in their reactivity with other molecules. Textbooks commonly describe enzymatic reactions as a “lock and key” fit. For each enzymatic reaction there is a specific reactant substrate that will fit the active site of a single enzyme type. It is the sole duty of each enzyme type to process a specific reaction involving only the substrate molecule(s) that fit its active site.

The benefit of using enzymes is that they function with extreme precision and work at an incredibly fast rate. This is ideal when a single known molecule is being targeted for destruction. The obvious disadvantage of enzyme-based cleaning solutions for draught beer lines is that there is a wide range of contaminants present, many of which are unknown. Sugar residues must be targeted using enzymes that specifically break down glucose, fructose, lactose, maltose, maltotriose, dextrins, starch, and any potential cross-linking between these sugars. In addition, enzymes that break the numerous peptide bonds within different proteins must also be present.

Last, enzymes that break apart cell walls of invading microbes and digest their by-products must also be present in the cleaning solution. Any chemical contaminant present that has not been degraded by the presence of a specific enzyme will essentially remain untouched. This is how enzyme specificity becomes a serious disadvantage when applied to draught beer line cleaning. It is inconceivable the number of different chemical compounds present in draught beer lines that need to be targeted for destruction and removed during cleaning. Although enzymes may be the fastest and hardest working of all cleaning compounds, they are impractical when tackling the array of known and unknown chemical contaminants that are present in beer lines.

Furthermore, enzymes only perform optimally under specific physical conditions. Temperature and pH are factors that limit enzyme activity. For proper enzyme function, both must be maintained exactly within the enzyme’s functional range, otherwise the enzyme will remain inactive or be denatured.

The preferred cleaning chemicals throughout the draught beer industry are acids and bases. They are cheap, easy to use, very powerful at low concentrations (2-3%), and rinse completely from a tap system due to their high solubility in water. Electrolytes have the longest standing reputation as an effective line cleaning chemical, as their use for this application began in the 1930s. Electrolytes are isolated naturally from the environment as mineral salts Sodium Hydroxide (NaOH), Potassium Hydroxide (KOH), Phosphoric acid (H3PO4) and Nitric acid (HNO3).

Cleveland Beer Line Cleaning uses only acid/base chemistry when cleaning beer lines. We have tested other chemicals and have found them to be effective, but none as dependable as the good old-fashioned electrolyte.

How Beer Line Cleaning Can Increase Draught Beer Sales

Draught beer line cleaning is performed for two principal reasons:

  1. To achieve proper sanitation, and
  2. to ensure product quality.

Maintaining a clean draught beer system is essential for preserving the integrity and character of each beer. The most common reason customers choose draught beer over bottled is for the freshness.

For a draught beer establishment to earn customer loyalty, it must meet the expectations of its audience. Clientele who are passionate about their beers will keep coming back if service conditions are right. The most important of those conditions is, of course, draught beer quality through proper sanitation.

There are a number of indicators of poor sanitation; and most customers, either consciously or subconsciously, will identify these factors and build an opinion of an establishment based upon them. Obvious indicators include off-flavors, stale aromas, and a lack of foamy head which results from poor tap system sanitation.

The conscientious consumer pays great attention to product quality details, and this practice flourishes within the draught beer and craft beer communities. There is a simple way to earn the respect, loyalty, and repeat business of this vast market of consumers: Provide consistent draught beer quality through proper tap system maintenance and sanitation.

5 Ways to Ensure Beer Line Cleanliness

1.) Use Fresh Food-Grade Materials

Whether your establishment is utilizing an older draught beer system or if you are shopping for a brand new tap system, using fresh food-grade materials is paramount in ensuring proper sanitation and draught beer quality. Today’s standards in tap system materials are stainless steel and polyethylene plastics. If you are purchasing a new system, be sure that all metal fittings, faucets, and couplers are made of food-grade 304 stainless steel. Older systems will commonly have brass or nickel parts which can easily and affordably be replaced with stainless. On large “long-draw” tap systems, the “trunk lines,” which make up the majority of the system (from the cooler to the faucets), should be manufactured from polyethylene tubing and enclosed in a glycol-chilled insulated packing.

2.) Replace Vinyl Beer Lines

A smaller portion of the system, referred to as the “jumper lines”, will be made of vinyl flex tubing, which connects the trunk to the keg couplers inside of the cooler. Carbon dioxide and nitrogen beer gas lines will often be made of vinyl too. Vinyl is utilized for this application because of its flexibility and resistance to kinking; but vinyl is not considered a food-grade material and these lines should be replaced once a year. Vinyl, unlike polyethylene, has a highly porous surface that will harbor sugar, protein, and microbial deposits that can permanently infect a draught system; therefore, it is best to simply replace these lines on an annual basis.

3.) Routine Caustic Beer Line Cleanings Every Two Weeks

Routine caustic beer line cleanings performed every two weeks by a qualified technician will greatly reduce the risk of microbial infection that may result in beer spoilage and the transmission of food-borne illnesses caused by pathogenic bacteria, mold, and yeast. Caustic solutions of either sodium hydroxide (NaOH) or potassium hydroxide (KOH) destroy sugar and protein residues that build up on the interior of beer lines, and remove microorganisms that reside and feed on these nutrient residues. These solutions should be used at a pH of 12-13. All beer must be purged from the system.

The lines should then be filled with caustic solution, given at least 10 minutes to soak, then all cleaning solution must be removed and the lines rinsed with fresh tap water. The rinse water should be run until its pH matches that of the fresh tap water (6.5-8.5) to ensure all caustic solution has been removed.

4.) Quarterly Acid Cleanings

In addition to bi-weekly caustic cleanings, quarterly (every 3 months) acid cleanings must also be performed to remove mineral deposits. Excess mineral buildup will create a rough interior on polyethylene beer lines, thus negating its anti-microbial effects and rendering it useless for food and beverage applications. To avoid mineral buildup in a tap system, be sure that acid cleanings are performed under the same criteria as caustic cleanings, but with a cleaning solution of either hydrochloric acid (HCl) or peroxyacetic acid (C2H4O3) at a pH of 2-3.

5.) Visually Inspect System Components Daily

Bar staff should visually inspect and hand-clean tap system components every day, and beer faucets should be cleaned every shift. Faucets will accumulate visible sugar and protein residues inside and out, and must be sprayed with an organic solvent such as isopropyl alcohol (rubbing alcohol) to remove them. Faucet brushes are available for cleaning the inside of faucets. Keg couplers should also be checked regularly. When visible residue buildup occurs, these residues should be removed using a toothbrush. Tough residues can be soaked in alcohol or dish detergent to break and remove these sticky protein and sugar films.

By following these simple guidelines, any bar or restaurant can be assured that they are serving draught beer at its highest quality and keeping microbial contamination to a minimum. Be sure to discuss these procedures with your draught beer line cleaner to make sure you are receiving adequate service, and educate bar staff as to the importance of daily in-house tap system cleaning regimens.

Why Draught Beer Line Cleaning is Essential to Your Business

Tap system neglect is more common than most bar patrons realize. Many bar and restaurant owners are not aware of the importance of regular line cleaning and assume they can go longer than is recommended between routine cleanings. As a result, draught beer systems often fall into disrepair, and the owners wonder why so few people are ordering draught beer at their establishment.

Tap system neglect will quickly result in sanitation problems that distinctly affect draught beer quality and cause severe functional issues. Within only a couple weeks after cleaning a tap system, beer lines, faucets, couplers, and foam detectors accumulate noticeable amounts of solid beer residue, or “beer scale.” These residues harbor bacteria, mold, and yeast, and cause moving parts to stick together and quickly malfunction. Routine cleaning (once every two weeks) will prevent these microorganisms from permanently infecting the system, while ensuring precise, dependable function of the entire tap system.

A poorly maintained tap system can fail any number of ways. Faucet, coupler, and foam detector valves collect sticky residues that prevent them from fully opening and closing, thus resulting in leakage. If the system is leaking beer, this leakage point also provides an entry point for microbial infection that will cause beer spoilage and undesirable souring.

Faucets will also “freeze up” as a result of dried sugar residue that essentially “glues” the internal parts of the faucet together.

Slow drip tray drainage is another common problem. If drains are not flushed daily with sanitizer they will fail, resulting in backup and overflow during high volume service. The backup is caused by an accumulation of sugar residue inside the drain tube, which also grows films of mold, yeast, and bacteria, as well as attract fruit flies.

These are just a few examples of why it is important to maintain the sanitary quality of a draught beer system. Routine cleanings performed by an experienced draught beer technician will prevent sanitation problems and alleviate most functional issues.

Need help with your tap system? Contact us today: 216.533.7936.

How to Increase Draught Beer Sales through Improved Service

In order to maintain a high level of draught beer sales, customer service must be top notch. There are simple ways for a bar or restaurant to encourage customers to order draught beer.

  • Menus must invite the customer to try what is on tap,
  • resources must be available that cater to individual preferences and curiosities,
  • and service and specials must follow suit of an intelligently designed beer list.

Guests entering the establishment should always be greeted with informatively designed menus. Just as there are many different varieties of beer, there are also many different varieties of beer drinkers. A good beer menu will consist of each beer’s name, style, alcohol content, the brewery and city the beer was brewed at, and a brief description of the beer’s characteristics.

A neatly assembled beer menu provides a comfortable approach to learning about new beers. Concise descriptions of character and origin bring comprehensiveness to a diverse selection. And if bartenders and servers are a dependable resource for further descriptions, customers will not hesitate to continue trying new beers.

Specials should be clearly posted inside the menu, as well as table tops, interior walls, and the entrance. Specials may be designed to showcase and promote draught beer. Certain draught beers can reappear throughout the menu as flavorings in cocktails (or “beertails”). Other beers may be suitable for cooking with and may be included on the lunch or dinner menu as ingredients in soups, beer cheeses, beer batters, mustards, and even malt vinegars.

Food pairings are another great way to introduce your customers to new beers. And be sure to offer happy hour pricing on a selection of draught beers. Design happy hour specials strategically so that they promote the sale of excess stock by encouraging guests to try beers they wouldn’t normally order. This will enhance their experience and expand their palates to keep them coming back.

Rotation is also key for encouraging repeat business. By continually introducing new beer varieties, regular guests will remain entertained. It is also important to be mindful of seasonal varieties and offer select beer and ale styles based on seasonal production. In addition, proper glassware should accompany each individual style of beer. Glassware styles and standards are designed to emphasize the focal points of each beer and exhibit the specific characteristics that define a particular style. Beer should be served with at least a quarter inch of head and presented in properly cleaned glassware.

As new beers come on tap, staff should be:

  • Continually re-educated as to the style and characteristics of each beer on the menu.
  • Knowledgeable and well-versed in drink, food and happy hour specials.
  • Able to provide accurate descriptions of menu options and helpful recommendations in order to satisfy guests and ensure their return.
  • Encouraged to taste each product so their descriptions are accurate and honest.

Are you having trouble serving the highest quality draft beer? Contact Cleveland Beer Line Cleaning today >

How You Can Tell if You’re Drinking from a Dirty Beer Line


We’ve all been there before. You sit down at your favorite bar, order a draught beer, and take the first sip. Only something doesn’t taste quite right. It tastes . . . dirty. Or flat. Or simply horrible. But what does that mean?

First, some of the characteristic indicators of a “dirty” beer line are the same for “dirty” glassware. These indicators are:

  1. Quick loss of head retention
  2. Lack of legs forming and remaining on the inside of the beer glass
  3. Seemingly flat beer due to rapid loss of carbon dioxide gas

All of these factors are related, but they can be the result two unrelated causes—a dirty beer line or dirty glassware. So let’s clarify the difference in terms of “dirty.”

Defining a Dirty Beer Line

The State of Ohio describes a “dirty” beer line as one that has not been kept in compliance with Ohio Administrative Code 4301:1-1-28: Beer and wine: cleaning and sterilizing dispensing apparatus. Although this code goes into no detail about how lines should be cleaned, what methods and chemicals should be used, or what the actual risks to the consumer are if beer lines are not kept to standard, it does state that line cleaning must be performed “not less than once every two weeks.” Therefore, by Ohio law, a “dirty” beer line is one that has not been cleaned by a registered line cleaner in over 14 days. How would you know this? Simply ask to see a bar’s line cleaning log. By law, all bars must maintain a log of their line cleaning, which will be initialed and dated by an Ohio registered line cleaner every time line cleaning is performed.

So how is “dirty” different from beer line to beer glass? A dirty beer line will have sugar and protein residue built up inside. These residues may break off when agitated by the flow of beer, resulting in chunks or flakes in the dispensed beer. This is an ugly surprise to the beer drinker, and quite embarrassing for the bartender and bar owner. Even worse, these pieces of beer solids harbor films of bacteria, mold, and yeast that will quickly spoil the beer once colonies are established inside the line. Even if beer flakes are not dispensed into the glass, be assured that residues do exist in the lines of unkept tap systems, and microbial biofilms harbored by these residues will taint the flavor of draught beer, leaving a sour or dry, cardboard-like taste in the beer, along with a loss of malty sweetness. It is mainly a variety of acids that are detected as off-flavors when sipping a beer that has been spoiled by a “dirty” beer line. These acids also break up the foamy head of a beer, wash those sticky beer legs from the inside of the glass, and expedite the release of CO2 from a once sparkly beer. If you think you’re detecting any of these off-flavors, or if you make any of these visual observations, then you’re probably drinking from a dirty beer line.  

Defining a Dirty Beer Glass

It is important to note that these same visual observations may also be made if clean beer is dispensed into a “dirty” glass. The flavor quality and sanitation of the beer will NOT be effected, so be careful before drawing any conclusions as to the cleanliness of the tap system. A “dirty” beer glass is any glassware that does not permit full contact of beer and glass. Beer sugars and proteins bind to glass resulting in full head retention and beautiful scaffolding of legs on the glass’s interior throughout the life of a pint, no matter how long or short that time may be.

So what could possibly get in the way of foamy head structure and leg formation on a glass’s interior? Well, anything else that sticks to glass. Sanitizers today, such as iodine, are designed to do just that in order to form a sanitary barrier between the glass’s surface and any potential airborne pathogens. This is great in terms of preventing the spread of foodborne illness; and this modern theory and methodology has been applied to all sectors of the food and beverage industry. Plates and silverware receive the same type of sanitary treatment, but the quality and presentation of food is unaffected by this. Rather it’s draught beer service that falls victim to modern sanitation methods.

If you suspect that sanitizer residue is killing the head on your beer, then ask the bartender to re-use your glass. Normally, a good first coat of beer on the inside of your glass will wash away sanitizer residue (consuming iodine will not hurt you) while laying a foundation for excellent head retention on your second, third, fourth . . . or fifth beer. If you notice improved head retention the second time around, then sanitizer was the culprit. Not a “dirty” beer line. This is more common than you may realize.

The second form of a “dirty” beer glass is one that is truly dirty. If it was washed with dirty water it will have an oily or greasy residue coating its surface, which repels water-based solutions like beer. This commonly results when bars do not change their wash-and-rinse water out frequently enough. This is also very common. Watch for a bartender’s or bar back’s attention to detail when running glasses through wash and rinse sinks, and also notice if glasses are being polished with a dry towel after washing and drying. The most important reason to polish is to remove any potential residues that will destroy the integrity of a quality draught beer.

In conclusion, if you order a familiar beer and it tastes and smells right, it is likely that you are drinking from a clean draught system. If you’re in doubt, look for visual indicators. And if you truly believe you’ve been served beer from a dirty beer line, ask to see the bar’s line cleaning log. Check that the date of their last cleaning is within two weeks. The date will be followed by the line cleaner’s initials and his or her 8-digit Ohio registration number.

Have any questions? Contact us today!

How to Maintain the Highest Quality Draught Beer

There are three factors that need to be optimized to ensure draught beer is at its highest quality—sanitation, refrigeration, and carbonation. All factors are equally important in terms of “quality,” but from a safety standpoint, sanitation is paramount.

A Technical Snapshot: How Beer is Made

The best way to imagine what it takes to maintain the integrity of draught beer is to consider the conditions under which beer is produced. This includes everything from mashing and boiling to fermenting and carbonating. Grain is mashed in water to release enzymes that produce simple fermentable sugars (maltose and glucose) for yeast to consume. The sugar water is then boiled to kill microorganisms (wild yeast, mold, and bacteria) while simultaneously adding hops to acidify and season the beer.

Historically, the acidity of beer along with the alcohol produced from fermentation was believed to prohibit microbial growth in a finished beer. While these attributes do inhibit bacteria, mold, and yeast, they do not prevent all microbial strains from growing. For this reason, most beers, with the exception of certain conditioned beers, are refrigerated immediately after fermentation is complete.

The Importance of Refrigerating Draught Beer

The general range of recommended refrigeration temperatures for beer is 30-39°F. Maintaining beer within this temperature range is important for four reasons:

  1. Bacteria, mold, and yeast are believed to be inactive at temperatures below 40°F.
  2. The ability of liquid beer to retain absorbed carbon dioxide gas changes drastically as the beer heats and cools.
  3. Oxidation (staling) occurs in beer more rapidly at higher temperatures, thus decreasing shelf life.
  4. Beer expiration dates are based on the assumption that the beer will remain at temps below 40°F from the distributor to the retailer to the consumer.

Consistent refrigeration is essential for maintaining the intended quality and character of draught beer.

The Importance of Cleanliness in Draught Beer Quality

Once a keg is tapped, the beer leaves the sterile environment within the keg and is exposed to a variety of factors that may compromise draught beer quality. Sugar and protein residues that are not consumed by yeast during fermentation serve as “leftovers” for other microorganisms to consume. These microorganisms are mainly airborne bacteria, mold, and yeast that will adhere to any surface that offers nutrient value (i.e. unclean beer faucets). Maintaining beer faucets that are free of dry beer residue (sugars and proteins) is the most important step bar staff can take to ensure proper sanitation of a draught system between routine line cleanings. When bacteria, mold, and yeast enter a draught beer line they continue to feed on the available nutrients in the beer, and their byproducts will alter the flavor and quality of the beer.

Inevitably, all draught systems will fall victim to microbial infection. Again, this is one reason why maintaining proper refrigeration temperature is so important. Refrigeration is crucial for maintaining proper carbonation and pour rate as well, and if you own an establishment that sells draught beer, then foamy beer equals lost profits.

The Importance of Beer Carbonation in Draught Beer Quality

Beer carbonation is measured in specific units called “volumes CO2,” and this volume is set to a specific rating by the brewery at a specific temperature prior to kegging the beer. Because the absorption of gas (CO2) in a liquid (beer) changes with temperature change (Henry’s Law), refrigeration temperatures must be kept constant to ensure the carbonation rating is consistent with the rating set by the brewery. If beer temperature is increased (above 39F), less CO2 remains absorbed by the beer, resulting in increased foam.

Choosing the proper gas blend for your system is also a critical determinant of carbonation and flow rate. Carbon dioxide/nitrogen (CO2/N2) gas blends became popular as the sizes of tap systems increased. The N2 content pushes the beer through the beer line while the CO2 is responsible for maintaining the proper carbonation rating.

In general, draught beer carbonation can be maintained by the retailer by pressurizing kegs in the same manner that a brewery uses to set the initial carbonation rating: using 100% CO2 at 10 psi (pounds per square inch) within the correct temperature range. This will maintain a desirable carbonation level while also balancing the keg with the restriction value of the beer line (induced by friction and gravity), resulting in just enough pressure to drive the beer to the faucet without over-carbonating the beer while maintaining a desirable pour rate.

That said, larger tap systems will often have restriction values too great and the keg cannot be balanced with the line using only 10 psi. In other words, 10 psi will not be enough pressure to deliver the beer from the keg to the faucet if the total line restriction (between the keg and faucet) is greater than 10 pounds. This is why additional pressure is applied with the help of nitrogen, an inert gas that is not readily absorbed by beer. Selecting the proper gas blend for a particular tap system requires knowledge of the system’s line restriction rating, static pressure, atmospheric pressure, and elevation.

Unfortunately, many bars today simply run a generic 50/50 or 60/40 (CO2/N2) blend instead of making the additional effort to determine the gas ratio that will correctly match the system to brewery-specified carbonation levels. Find a qualified draught beer technician who is willing and able to do this.

Carbonation, refrigeration, and sanitation issues are common, and usually result from poor maintenance or a lack of attention to detail during installation. Industry professionals should perform routine inspections, which can save the retailer thousands of dollars annually, especially when foaming issues are corrected. Equally important, the retailer must respect specifications and quality standards set by breweries, and take any measures necessary to ensure that only beer of the highest quality and integrity is served to their customers.

The consumer should expect nothing less.

Do you need help maintaining the highest quality of draught beer? Contact us today >