Producing a quality product consistently is the key to success! Every brewer has the capability of monitoring process and product to determine level of consistency and quality. Every brewer can and should monitor and evaluate critical points in the brewery. Basic record keeping is essential to establishing consistency and developing a Quality Control and Quality Assurance program.
Quality management conducts and supervises the methods to achieve the desired level of excellence, efficiency, and company profits. Its main components are Planning, Quality Control, Quality Assurance and Quality Improvement.
The goal of a QC/QA program is to measure specific conditions throughout the brewing process to keep the beer product within the intended specifications to achieve and ensure the final product is consistent. However, evaluating the final product alone will not replace an evaluation of the entire brewery process on a regular basis.
To accomplish an excellent QA/QC program, the brewery has to establish Standard Operating Procedures and laboratory space with qualified personnel (or develop a good understanding of industry methods) and instruments to be able to fulfill all the established specifications required to meet target standards in the entire process. It has perhaps never been said better than by Melissa Antone in her article, Building a Quality Control Lab: “The beer quality lab is no longer a concept reserved for large breweries with endless budgets. With the growth of the craft beer industry has come the availability of tools and resources curated with smaller breweries in mind.”
There are five major points for controlling quality: Equipment, Wort, Fermentation, Yeast Management, and Documentation.
Know your system and its limitations. Many brew systems have weak points that can potentially cause problems. Scratches, dead ends, and shadow areas that do not receive adequate exposure of chemical must be avoided. A consistent cleaning and sanitizing regimen must be followed according to your chemical supplier’s recommendations. It is important to be certain that you are using proper concentration levels, temperatures, and contact times for your chemicals. It is impossible to sanitize a surface that is not clean; and all organic matter must be removed before sanitation can occur.
The term sanitized is not always well understood. Sanitized does not mean sterile. Good sanitation and sanitary practices lead to limitation of microorganisms but does not guarantee that they are eliminated. A smooth surface that has had all of the organic matter (such as dead yeast or wort residue) removed is relatively easy to sanitize because there is no protection or food for microbes. In contrast, a rough surface or a surface that has not been adequately cleaned is very difficult to sanitize because microbes are able to find protection from your chemical cleaning. Use of hot water as a sanitizer should be avoided. Thermophiles can survive high temperatures, so use of a no rinse sanitizer or a sanitizer followed by a sterile water rinse is essential.
In general, the most common sources of contaminations are heat exchangers and old cracked hoses. Each of these locations offers cracks and crevices for microbes to take shelter in. Regular inspections of surfaces are essential for consistent results. The heat-exchanger should be adequately cleaned and sanitized following each brew session.
Knowing that your equipment is well maintained, clean, and regularly inspected and tested will form the foundation to consistent, quality beer. In the event of a contamination issue, a well-documented cleaning program will help to take some of the guess work out of determining the source of contamination.
Now that you are confident in your equipment, it is time to focus on your wort. If your equipment is clean and well maintained, it is relatively easy to produce stable and consistent wort.
Adequate record keeping will allow you to track the consistency of your wort. It is very important to monitor and record as many points as possible such as original gravity, pH, length of boil, percent evaporation, timing and quantity of hop additions, addition of any coagulants, and any other relevant data. Once again, if you have good, consistent records it becomes much easier to troubleshoot in the event of a problem.
Wort must be boiled vigorously in order to achieve a proper protein break and to kill any possible infecting microbes present. An 8-10% evaporation in 1 hour is a good target to shoot for, but each brewery will have slightly different capabilities. Adequate protein removal prior to running into your fermenter is important for beer stability and consistency. Use of kettle coagulants and a well-designed whirlpool will aid in the removal of excess protein.
It is important that a brewer regularly check the fermentability of the wort produced. A very simple and effective method is a forced fermentation test. This test can be performed by any brewer. The forced fermentation test consists of aseptically pulling a wort sample (post heat-exchanger) into a sterile sample container and inoculating with a very high yeast cell count. Agitate the container often. Check the gravity after 36-48 hours to determine terminal gravity. This test will give you a good idea of where your fermentation should finish. If your main fermentation does not reach the same level as your forced ferment, you know you have a problem in the fermenter (pitch rate, temperature, oxygenation). If both your main fermentation and the forced ferment finish out of spec (too high or too low), you know that you have a problem on the brewing side (mash temperature, times, crush, ingredients).
During the brewing process several quality control samples should be taken to track consistency in every batch. For each QC sample taken from each brewing phase, specific gravity and pH is measured to determine and monitor if the standard requirement has been achieved.
Lauter TunFirst WortLauter TunLast RunningsKettleEnd of BoilHeat ExchangerKnock Out
|Lauter Tun||First Wort|
|Lauter Tun||Last Runnings|
|Kettle||End of Boil|
|Heat Exchanger||Knock Out|
|Recommended Test Options||Checkpoints / Targets|
|Density / pH||Several points as indicated above, to monitor consistency|
|Forced “fast” Fermentation||Sample taken from post heat exchanger. In the brewery lab, same yeast is pitched into sample to determine final gravity in 3 days or less.|
|Cell Counting||After filling the fermenter, or after every batch in multiple brews, to determine if the goal was achieved.|
|ATP testing||To verify the fermenters or any other vessels are completely clean after CIP|
|Microbiological plating with selective media||To detect beer spoiling bacteria such as Lactobacillus, Pediococcus, etc.
For harvested yeast to verify it is not contaminated
|NBB-B-Am Doehler culture media||For detecting bacteria from biofilms|
|Flood Plating||For wort and beer samples|
|Membrane filtration||For water, wort, and beer samples|
Once the wort is transferred to the fermenter several additional samples are required to keep track of a good fermentation or to catch any issues on time.
The following information should be kept on records from each batch and fermenter in use. Some of the information will be taken daily until the complete fermentation and maturation is done.
- Set Temperature
- Actual temperature
- Specific Gravity
- Head Pressure
Your equipment is properly cleaned and maintained, your wort is consistent and stable, now make sure all of your diligence and hard work are rewarded with consistent predictable fermentations resulting in great beer.
Yeast performance is tied to many factors. Everything that you do during the brewing process will have an effect on the yeast that is converting the sweet wort into beer. Once again, good record keeping on the entire brewing process will help to maintain consistency and to locate inconsistencies that could be causing a change in yeast performance or beer quality. The importance of pitch rate and oxygenation cannot be stressed enough. Adequate pitch rates and oxygenation will help to minimize the impact of inconsistencies in the brewing process. Fermentation tracking will also allow a brewer to maintain good, consistent fermentations
Cell counting should be incorporated into routine brewery procedures. A guaranteed cell density on a fresh lab culture does not replace the value of in-house evaluation and confirmation of target cell densities at multiple stages in the brewing process. Cell density should always be checked on propagated yeast, harvested yeast, and after knock out to determine if the target yeast cell count was achieved.
Documentation and Tracking
The importance of good documentation cannot be over emphasized. A microscope is not needed to keep good records. Information can be kept in a logbook or on computer file, which tracks all information pertaining to the brew. The following are suggestions for documentation and tracking information.
- Strain ID
- Package Code
- Date received
- Condition received
- Package Size
- Beer style, volume, date
- Temperature at pitching
- Pitching rate in cells/mL
- Fermentation Information
- QC Tests and results
Good fermentation records are valuable when evaluating yeast performance over a period of time.
Brewing specs per batch:
- Wort cooling/Run in time
- Wort aeration
- Fermenter volume
- Yeast pitching details
- Gravity and temperature daily
- Time to half gravity or set target (i.e. 5 °P)
- Final gravity
- Cooling time and date
- Forced ferment sample
Common Yeast Related Beer Flaws
|Off-flavor||Taste / Aroma||Causes||Resolution|
|Estery / Fruity||Banana||Normal yeast strain characteristic
High fermentation temperatures
|Adjust pitch rate according to gravity
Control fermentation temperature
|Diacetyl||Butter||Produced by yeast during fermentation
High fermentation temperature
Control fermentation temperature
Poor yeast health condition
|Brew with yeast in good health condition|
|Sour / Acidic||Sour, Acidic||Wild yeast contaminant
Bretts or bacteria
|Proper CIP sanitation
|Sweet||Sweet wort||Stuck fermentation
Low viability and vitality
Brew with yeast in good health condition
|Acetaldehydes||Green apples||Yeast by-product in primary fermentation||Yeast will absorb it during fermentation|
|Sulfur||Sulfur||Yeast by-product||Yeast will absorb It during maturation|
A beer batch brewed that starts fermenting under normal conditions, suddenly after halfway through stops or ferments very slowly is considered stuck or stalled, and in the long run can cause a loss to the brewery.
Some of the principal causes of this incident are:
- Yeast viability
- Lack of wort nutrients
- Malt quality
- Low or insufficient oxygenation
- Pitching rate
Techniques to Restart a Stuck Fermentation
- Check temperature and raise it
- Rousing with CO₂
- Check pH, if to low this will inhibit the yeast
- Check for possible contaminations