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Special Beers: The Case for Pasteurization

“It doesn’t taste like what we wanted it to” was the quote used at a recall of a Bourbon-barrel aged beer that was infected with alcohol-tolerant Lactobacillus acetotolerans, a souring bacteria.

American brewers have pushed boundaries of traditional brewing with the development of barrel-aged beers, with previously-used wine barrels, bourbon and sprits barrels, and with installation of foeders (wooden beer tanks) in their cellars. Beers no one imagined 20 years ago are finding their fans and making names for the breweries that produce them.

Over 100 years ago, it was only the British who used unpitched wooden beer casks, and the special flavors of Brettanomyces were prominent in many ales of the times. In continental Europe and in North America, the use of pitched beer casks, (casks lined with a flamed-on resin) (a kind of natural plastic with a very mild taste and aroma),  prevented beer from contacting wood and offered a smooth and cleanable surface.

Spirits casks expose the contents to direct wood surface contact. The uneven surfaces and spaces (pores within the wood) offer surfaces for microbial adhesion and colony growth. And with the fact that the surfaces are no longer flooded under spirits, one expects to find species including Zymomonas, Acetic acid bacteria, Candida, Zygosaccharomyces etc. present. 

Even typical ‘gut’ bacteria are favored by high concentrations of potential prebiotic components like arabinoxylan, beta-glucan and Maillard products like melanoidins (1). And many brewers these days have opened Pandora’s box for wild inoculations and spontaneous fermentation processes that allow them to express their terroir… microbes represent the new terroir.

Oak barrels are porous and air and microbes can be transported in and out. And the number of breweries using open-top coolships to cool wort in their brewhouses is impressive.

It should be clear that putting any beer, even if high-alcohol and high-hopped, in a cask and ageing it inside the cask, will inevitably bring microbiological challenges. Brewers are taught well on the antimicrobial properties of hops, but a second style of beer presents new microbiological challenges…

The growth of dry hopping as a brewing technique (adding hops cones, pellets, or powder directly to fermenting or already- fermented beer) naturally leads to rogue microbes gaining a new foothold in bulk beer.

Belgian brewers flavor their lambics with cherries and raspberries to make kriek and framboise, and these classic styles served as inspiration for countless North American breweries. Innovative beverages based on natural cereal and berry products have gained consumer attention and may open new opportunities for the breweries.

And the now-common practice of including loads of fruit in beers to deliver special flavors increases opportunity for undesired microbes to enter precious beer, often via species found on the skins of fruits. “Fruit” is a broad term with so much variety and also the form of the fruit. It is not uncommon for American breweries to add 8-25 lbs of fruit per barrel, and quite frequently, the addition is on the cold side.

Saccharomyces cerevisiae var. diastaticus is a natural variant of brewer’s yeast Saccharomyces cerevisiae. While cultured yeasts are essential for beer production, wild yeasts including S. diastaticus allow for a secondary fermentation in tank or in final package. Other wild yeast species of concern include Debaromyces, Brettanomyces Dekkera, Pichia, Hanseniaspora, Kluyveromyces, Torulaspora, Williopsis (2). And different fruits can bring in mycotoxins such as Ochratoxin A and Patulin (3).

Yeasts and vegetative cells of bacteria are typically very sensitive to heat; Yeast D-values (an indication of death rate) rarely exceed 1 min at 55 °C…but Shearer et al. (2002) did find a S. cerevisiae showing D values of 13 s at 71.1 °C in apple juice. Yeasts and vegetative cells of bacteria are typically very sensitive to heat (Stratford 2006). Yeast D-values rarely exceed 1 min at 55 °C.

Vegetative cells of beverage-spoiling microbes are usually more thermotolerant than bacterial pathogens or protozoans (Tribst et al. 2009, Lawlor et al. 2009). Shearer et al. (2002) found S. cerevisiae showing D values of 13 s at 71.1 °C in apple juice. Yeast ascospores can have 30–350 x higher thermotolerance compared to vegetative cells.

For example, D60 °C values of 7–22 min have been reported for asci of S. cerevisiae (3). A heat resistant Pediococcus sp. required 16 s heating at 71.1 °C for 5-log reduction in a simulated apple cider (Piyasena et al. 2003). Pasteurization treatments used in the beverage industry are usually sufficient to inactivate all species of concern, and most enzymes which otherwise could be adding fermentable sugars into the packaged product over time.

Many things occurring in the brewing processes are not 100% under control of the professionals. Packaging is. There is a mission-critical component within packaging that serves as our last layer of protection on beer that will soon leave to the wide world.

By virtue of applying heat within the contents of the already-sealed can or bottle, a PRO Pasteurizer is a proven means to offer long-term shelf-life stability with no impact on integrity of the package. A gentle passage under the water sprays in the pasteurizer, controlled heating in the PRO Single Zone Batch Pasteurizer or heating, then cooling in the PRO Triple Zone Batch Pasteurizer or a PRO Tunnel Pasteurizer, of the individual package contents… can result in confidence and security in the packaged beer.

As breweries in the USA increasingly move from the traditional can liners to ‘BPA- non-detectable’ materials applied to can interiors at their manufacturing plants by waterborne styrene-acrylic spray, waterborne non-BPA epoxy spray, or waterborne polyolefin dispersion spray, there have been no indications of de-laminations so adherence is the same as existing, proven liners.

And though it is true that sleeved cans (where a ‘brite’ (or unpainted can has its label heat-shrunk on the can body)  does temporarily ‘relax’ while the can is in the pasteurizing zone, this author has seen many examples where there is no evidence of any concern, no occurrence of water bubbles under the sleeve… but it can occur so prudence in qualifying sleeved cans from the sleeving service providers out there is called for.

Authored by Jaime Jurado

Past President-MBAA(Master Brewers Association of the Americas)
https://www.linkedin.com/in/jaimejurado/
https://independent.academia.edu/JaimeJurado

Article References: 

  1. https://lib.ugent.be/fulltxt/RUG01/002/482/227/RUG01-002482227_2018_0001_AC.pdf
  2. http://nik.waszczak.com/wp-content/uploads/2015/04/Microbiological-stability-of-beer.pdf
  3. https://www.vtt.fi/inf/pdf/tiedotteet/2011/T2599.pdf

ABOUT US:
PRO Engineering and Manufacturing was established in 1977 by Ed and Dave Michalski as a steel fabrication shop. For more than 40 years, PRO Engineering and Manufacturing, Inc. has been delivering solutions for beverage product shelf stability and consumption safety. As leading innovators in post-fill pasteurization, our skilled team offers the best in high-quality pasteurization equipment.

CONTACT US:
Phone: 414-362-1500 | Email: [email protected]

Brewmaster Sensory Controls

Using the Senses for Brewery Observations and Process Control

The senses referred to are Sight, Sound, Touch, Taste and Smell. They are powerful allies for process observation and control with encouragement, training and proper application in the brewing environment! Brewers have keen senses, and this is obvious when participating in taste panels with BJCP certified judges who taste a multitude of brewed products.

The purpose of this paper is to discuss actively using those senses during the actual brewing process, well before packaging. Our goal is to find problems, to assure processes operate as we believe they should, and to monitor that our ingredients and output taste, as we believe they should.

A quote shared: “There is no replacement for knowing how your equipment (and beer) should sound, look, feel, smell or taste. As part of the training I do here, I try to impress upon everyone that they will probably know when their equipment starts going bad because “something” will be different, and that’s the best time to call maintenance.” Abraham Kabakoff, Dipl.Brewmaster.

Our senses were the QA systems of the past.

Recall the story of the brewmaster in lederhosen testing fermentation by sitting on some of the beer: If it stuck to his seat, it was not finished (residual sugars) and needed a little more time. I believe our senses have an even more important role to play in the breweries of today [lederhosen optional].

The use of enclosed control rooms, the increased reliance on QA’s analytical data and the reduced staffing of modern breweries has seemingly diminished the importance and the opportunity to use our senses for process observation and evaluation. In this writer’s opinion, the proper and regular use of our senses is a low cost, pro-active step that can help assure the operation is under control. The senses are a strong complementary skill to process knowledge and training.

This issue of PRO Tech Notes will provide examples of everyday process issues found directly by sensory evaluations in the field. These include flavor issues of several types, Plato and RDF problems, lost capacity, lost extract, yeast issues, sewer loading increases, microbiological problems and CIP problems.

Additionally, we have outlined a five-step program to assist you with using your senses at your plant.

Brewhouse Operating Environment & Contamination Potential:

The responsibility of the brewhouse is make high quality wort. This wort must be fermentable, have the proper °ß, pH, IBUS, color and flavor, it must be sterile and free of “contaminants”. Brew volumes should be consistent. So…. what could possibly go wrong if we understand the expectations? Let us count some the ways….

1. Operating Environment: The brewhouse environment is exceptionally challenging. Equipment is subject to high duty cycles, a wide range of pH, high flow rates, abrasive materials in the grain and mash and corrosive materials. Utility consumption is high, and our process relies upon efficient use of various heat exchangers. Lauter tubs are mechanical in all operational steps. Our senses can provide detail unseen on the HMI touch screen. (Human Machine Interface)

2. Contamination Potential: Some (but not all) potential sources for ‘contamination’ of the mash, wort and brewing waters include the following: caustic, air, underdough, water, steam condensate, unmilled grain, over-milled grain, unmalted barley mixed in with malt, off quality malt, vent stack condensate, wort from preceding brews, spent hops, spent grain, left-over hot trub and pump- seal water.

Examples of brewhouse problems found by using the senses:

• Vorlauf duration can have a negative effect on wort taste after a particular duration. In some open or semi-closed grants, tasting the wort has shown flavor changes after about 8 minutes, with oxidized flavor notes appearing.

SAFETY NOTE: Circulating wort is usually about 170°F. Caution is required during collection and tasting!

• Wort flavor during Vorlauf can be a predictor of beer flavor. This is especially true of harshness and astringency that can be part of a milling impact and the types of grain used. We encourage brewers to taste the wort (carefully!! it is hot!) on each brew, throughout the runoff stages to understand brand profile and to find issues. In a combination vessel, one brewer reported that he had detected low-balling wort through taste without using his hand-held device.

• Tasting wort during runoff has found supplier issues. In one case, a very low- level sourness inherent to the particular batch of malt was quickly identified through taste, during runoff. The brewer tracked the product through the process to make appropriate handling decisions.

• Watching Grain-Out has visually confirmed a layer of starchy material at the false bottom that was affecting run-offs. Physically probing the false bottom with a mash oar on succeeding brews indicated the stainless steel false bottom was coated over and could not be touched. Changes in mash procedures eliminated the starchy layer and improved the wort and the final beer flavor.

• Watching underlet water enter a lauter tub identified that one particular tub was tilted by about 1/2”. This explained why it was the lowest yielding tub of all in operation. This physical observation combined with records of efforts to improve its yield were the justification for engineering changes.

• Tasting wort from lauter tubs with plant engineers identified that one of three pumps on a particular lauter tub was putting out slightly sour wort. We touched run-off tubes going to that pump until we found a cold section, indicating blockage. We followed through by touching the bottom flush system during its operation. We heard and saw the valve actuate but the valve stem did not turn. The pin had fallen out and no bottom flush water was going to a section of the tub. This was confirmed by touching the piping on the downstream side of the valve. Underdough was not being removed in one section of the tub. The Underdough built up and plugged some of the tubes. Souring started and wort quality had started to suffer. The problem was identified in advance of seeing it on QA records.

• Air Vents and steam traps are small but critical pieces of utility equipment. Air vents assure air is purged for proper heat transfer during start-up and they help prevent a vacuum when steam is shut off. Steam traps assure only condensate leaves the process. Inspections at vessels frequently find problems with both devices. In one case, the air vent lines were plugged with fittings from initial pressure testing, far in the past. Removing the plugs improved heat transfer.

• Biofilm in a wort line was identified by touch when the writer saw a valve being replaced in a wort transfer line. The writer put his hand in the pipe to verify the line was clean. It had an unexpected biofilm about 1/8th thick. Changes in cleaning equipment and CIP procedures cleared up the problem. Beer taste improved. The biofilm had contributed to the “house character” of the beer.

Fermenting:

Fermenting is less of a physically demanding process than the brewhouse operation. Observations change to cover those critical processes important to that process area. Problems found using the senses along with other analytical skills include:

• Fermenter Stratification: Visual changes of CO2 generation in fermenters have provided clues to fermenter stratification. Additional analytical steps verified the conditions. See MBAA Technical Quarterly, Vol.45, #2, 2008.

• Aroma of CO2 identifies brand fermentation characteristics and provides a clue to yeast health.

• Physically (and cautiously) touching the water side of the wort cooler lines during wort cooler CIP has identified plate failure due to heat stress corrosion. Plate failure is an eventual fact of operation. It can lead to other serious quality problems in the process.

• Wort air injection systems need to be checked visually and cleaned on a regular basis. Check valves fail; wort can back up into the system, causing micro problems.

• CIP: Several CIP issues have been detected by simply listening to the CIP in operation. High- pressure jets have a particular sound. When they fail or have insufficient pressure the sound changes. We catch problems by sight as well: Vessel Pre-rinse-to-Drain shows solids for a period of time.

If the time solids are flowing to the drain is too short, there may be problems with the cleaning jets. Catching such problems while in the field can prevent micro issues down the road. Visual tank inspection after CIP is important to assure cleanliness and drainage.

• Crushing Tanks: Tanks have been crushed in many ways over the years. The author has seen the effects of using a “cold” water rinse following a “hot” CIP. The hot CIP vapor in the tank is quickly condensed, resulting in negative pressure conditions. The tank can collapse quickly. All senses can detect that problem….it is noisy, it is ugly to see, you can smell trouble coming and the mouth goes dry! It is important to train the brewers on the potential of the issue.

Active controlling instrumentation on the water supply line to the vessel is a wise precaution. Establishing a standard for the allowable difference between caustic temperature and rinse water temperature is critical. Cooling down of a sterilized tank with CIP rinse water can be disastrous.

• Welds: Welds in brewery lines should be full penetration with proper line purges. Sugared welds can and have been sources of bacteria growth*.

Filters:

After fermenting, the beer should have no contact with O2! Unfortunately, there are many process points where air contamination and oxidation can occur: Every beer transfer; tank purges, centrifuge cover gas, transfer hoses and transfer piping are some examples where O2 contamination must be excluded with proper procedures and checks.

Similarly, we need to assure that deaerated water is actually deaerated. Visual checks inside deaerators help assure they have not scaled over and the same visual checks assure de-scaling is successful when undertaken.

Tools such as a Zahm and Nagel gas purity-testing device are especially useful for checking the purity of purged tanks! Tasting CO2 (bubbled through sterile water) helps assure quality standards are met and that we can be confident that no off odors will enter our product from the CO2 we purchase.

Similarly, the DE we plan to use should be mixed with water and the product sniffed (not tasted), looking for off notes, especially moldy or musty notes than can be picked up in some storage conditions.

* Pro Engineering has certified welders and inspectors who can audit your process and help teach brewers to ‘read welds’, a useful skill.

One example of a problem found through the senses is below:

A beer filter at one brewery was experiencing short cycles, and therefore very high downtime and high process loss. The author and an associate were sent to assist. They observed blowback and filter cake rinsing from the filter body sight glass.

It was not actually happening! The filter shell was opened and the filter cake ‘blow down’ system was started manually. The two observers were soaked. The seals on the water supply header had failed. Almost all the water sprayed out horizontally, along the shaft.

The little water arriving at the spray nozzles was insufficient to rinse off any of the old DE. The filter screens were mostly bridged, and rinsing was ineffective until repairs were made. The decision to observe filter blowdown in the field was the key to problem identification and resolution. 

__________________________________________________________________

A brewery wishing to incorporate the use of the senses into their operation might consider the following:

1. A well-designed process audit is a good place to start. Process auditors such as those working with Brewing Consulting Services are good listeners, observers and problem solvers. We work with you and your staff to hear your concerns and see your process in action.

2. An audit can be followed with development of Critical Process Observation Standards and Expectations. Pro Engineering has the staff and expertise to correct problems found during such an audit. Alternatively, they can work with your staff to assist as needed.

3. Step three has options. Selected key personnel can be trained one-on-one with the idea being that they will train the remaining staff on the use of the senses for assuring quality and for understanding the process. Alternatively, groups can be trained. Time in the field is important, but discussion of key steps in the process is equally important.

4. Step four involves assuring that information about use of the senses becomes part of plant operating procedures. When properly done this become part of management expectations. The training is formal and includes the how-to, when-to, why and where to use our senses for process auditing and control. The plant must integrate safety into the training, since we are sometimes dealing with hot liquids and gas such as CO2.

Use of the senses should become part of internal process auditing and a part of future training for new brewers. As the process changes, as new equipment is purchased, as the business grows, the use of the senses for process observation and control should evolve as well. Issues found by use of the senses often have ROI justification for repair.

5. Step five, correcting identified issues: Pro Engineering has skilled craftsmen knowledgeable in the brewing process who can assist with repairs and upgrades in conjunction with your staff and with their cooperative relationship with Brewing Consulting Services, LLC.

We hope that this issue of PRO Tech Notes TM has given you some ideas on how to use your senses to brew better beer. We welcome any feedback, discussion or questions that you may have. If you need assistance with your brewing process, please contact PRO Engineering and Manufacturing Inc.

A brewery wishing to incorporate the use of the senses into their operation might consider the following:

1. A well-designed process audit is a good place to start. Process auditors such as those working with Brewing Consulting Services are good listeners, observers and problem solvers. We work with you and your staff to hear your concerns contact either of the individuals listed below, they will be very pleased to help you. David Kapral, Founder Brewing Consulting Services, LLC

The author, David Kapral, has over thirty years of brewing experience. Some of his credentials are:

  • Experienced Brewmaster, with 8 years consulting experience to craft brewers across the U.S.
  • Beer Steward Certification Trainer for the MBAA
  • Practical Brewing lecturer at MBAA’s annual Brewing course in Madison, WI
  • Member of the InTota Expert network
  • Received the “Inge Russell Best Paper Award” for a complex fermentation topic

Additionally, Mr. Kapral founded Brewing Consulting Services, LLC. The company provides a wide range of practical operational advice and solutions to clients in the craft brewing industry. The group includes the David Kapral and Associates Mark Sammartino and Pat Frost. Collectively this group has about 100 years of experience in the industry.

Contact David Kapral if you would like to discuss the issues raised in the article or if you want to explore further assistance from his firm. (208) 938-2064 [email protected] www.davidkapral.com

Ed Michalski, CEO PRO Engineering and Manufacturing, Inc PRO Tech NotesTM is a publication of PRO Engineering and Manufacturing, Inc. PRO Engineering has been providing equipment and engineering services to the brewing industry for over 35 years.

© David Kapral and PRO Engineering and Manufacturing, Inc PRO Tech Notes TM is a trademark of PRO Engineering and Manufacturing, Inc.

Authored by David Kapral
Founder/CEO: Brewing Consulting Services, LLC Award-Winning Brewmaster and Lecturer

Sponsored by Ed Michalski, CEO PRO Engineering and Manufacturing, Inc

PRO and Manufacturing, Inc has been providing equipment and engineering services to the beverage industry for 42 years. Contact Ed Michalski, CEO at: (414) 362-1500, [email protected]

ABOUT US:
PRO Engineering and Manufacturing was established in 1977 by Ed and Dave Michalski as a steel fabrication shop. For more than 40 years, PRO Engineering and Manufacturing, Inc. has been delivering solutions for beverage product shelf stability and consumption safety. As leading innovators in post-fill pasteurization, our skilled team offers the best in high-quality pasteurization equipment.

CONTACT US:
Phone: 414-362-1500 | Email: [email protected]

ABOUT US

PRO Engineering/Manufacturing, Inc. was established in 1977 by Ed and Dave Michalski as a steel fabrication shop. From this modest beginning, complete machine fabrication capabilities were quickly added followed by the installation of our own in-house engineering and design group.

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