Tag Archives: quality

The real quality issue: Oxidation

The recent buzz about the lack of quality in some of the new breweries is gaining noticeable momentum on the internet and social media. I have written much in this blog about beer quality and what every brewer should have in their arsenal to deal with quality issues.
Many people talking about beer quality refer to infected beers, beers with diacetyl, DMS (creamed corn) and beers with acetaldehyde. Those problems still exist, but in my experience are becoming increasingly rare, because good brewers are starting to understand these compounds and how they are formed, much better than 20 years ago. As an example, I can tell you that in the late 1990’s, at beer judging events, diacetyl (butter) and acetaldehyde (pumpkin seed) were common defects. Now, not so much.

One quality issue that is rarely addressed by the general public, and even some brewers, is oxidation (excessive exposure  of beer to air). Air can come in contact with beer a number of ways: if tanks, hoses and piping in the brewery are not adequately purged w/ CO2 or hot water, if there are equipment issues, like leaking pump seals or damaged valve seats, and in the packaging process, and especially if bottles and cans are not properly purged and sealed, oxygen can get absorbed into the beer-and the oxidation reactions that occur create all sorts of bad flavors. Oxidation is hastened by warm temperature storage of packaged beers, and lack of care in avoiding air contact post-fermentation before packaging. There are several reactions that can occur in the brewhouse that can hasten oxidation in the finished beer, but the important thing is to control exposre to oxygen in finished beer before packaging. I’ve heard many brewers say “nothing good can happen to your beer once it is put into a package”. And by and large, that is true, though of course some higher alcohol beers benefit from the changes that occur with aging.

The bottom line is that once yeast has completed the fermentation, the beer needs to be kept oxygen free and isolated from any oxygen exposure or contact risk.
So what does oxidation tastes like? It really depends on the beer, but as a beer ages the following flavor changes often can be observed. Excessive air contact will accelerate this flavor development:

1. In a dry-hopped beer, the first thing that happens is a rapid loss of hop aroma and flavor
2. In most beers, the malt flavor changes from a clean fresh malt character, to a worty and grainy flavor, eventually morphing into a strong and coarse grainy character, then developing to the dreaded wet cardboard papery flavor.
3. In beers brewed with a high percentage of crystal malt, the caramel and toffee like flavors evolve into a dried fruit flavor, raisins or prunes. In addition, these oxidized crystal malt characters will also mask and hasten the loss of hop flavor, which is why many of the best IPA brewers use very little to no crystal malts in their IPAs.

Some air pickup during filtration and packaging is normal, and in many cases unavoidable. But managing the air pickup to minimize oxidation is where the skill of the brewer comes into play. It’s a notoriously difficult situation to control, and some brewers are much better at it than others.

Brewers should always keep museum samples of their bottled beers and evaluate them stored cold and at room temperature once a month for 3-6 months. The resulting flavor differences are staggering, which is why it frustrates me to see craft brewers put 6 month code dates on their beer. I wonder who actually bases their code length on taste and who is simply making a bad assumption.

How does a beer drinker know when a beer is hopelessly oxidized? The only way to really know is taste. That said, before purchasing a beer, here are some clues:

1. A liquor or beer store that stores their beer on a shelf without refrigeration. Dusty bottles are a dead giveaway. Oxidation reactions occur faster with warmer temperatures, so non-refrigerated beer on a shelf in a retail account is always a danger sign.

2. If the brewer date codes their beer (and all brewers should do this, but too many don’t) any lower alcohol beer (below 8% abv) that is more than 2-3 months from packaging should be approached cautiously.

3. Slow moving beers at large multi-tap establishments should be approached with caution. Especially the lower alcohol or hop forward ones.

Now that we are contemplating selling our beer in Europe, we are finding that many countries require ridiculously long code dates on beer. 180 days and 270 day code length requirements are not uncommon. Obviously we have a long way to go to educate people that beer, like bread, stales. I always tell people to treat beer like milk. Keep it cold, all the time. It won’t go bad and make you sick like spoiled milk can, but the flavor does change based on temperature, and for most beers the flavor changes are not good.




What is quality? Part 2

So after I ranted a bit last week about brewers who don’t invest in quality and how that can harm everyone who makes beer for a living, I thought I’d take some time this week to review a little bit more about what it takes to brew a quality beer (or a “proper pint” as they say in the UK).

I hit on a few elements that I think make a quality beer in the previous post. These are:

1. Consistency from batch to batch. Admittedly, this refers to a brewery brewing and packaging a core lineup of beers. Although a brewpub that makes a few flagship beers or regular offerings should strive for consistency too. Philosophically, I disagree to some extent with the notion that a small brewpub/nanobrewery/farmhouse brewer can successfully embrace variable beer flavor caused by seasonal changes to recipes and variability in ingredient flavors, but I understand the attraction to this kind of brewing. For them the question becomes: “Did I make the beer I set out to make?”

2. Lack of off-flavors. Some people don’t agree or don’t care, and many beer drinkers don’t have a good understanding of this, but the presence of off-flavors like diacetyl (butter) and acetaldhyde (pumpkin seed) is a strong indication that the brewer doesn’t have a good grasp on the basics of managing the fermentation part of the brewing process. Too many brewers focus on recipe formulation and the brewhouse operation, but fermentation is by far the hardest part of the brewing process to manage. The idea of managing a living organism (yeast), and controlling it to the extent that you get proper amounts of growth, the flavors produced by the yeast are flavors you want, and the yeast is healthy and happy though several rounds of repitching to fresh wort is daunting to say the least. It requires the utmost focus every day. And it requires good sensory skills and knowledge, so the brewer can determine if things are going as planned, and if not, take immediate steps to rectify the situation.

Other off-flavors:

The presence of DMS (Cream Corn flavor) is indicative that the boiling process in the brewhouse is not as vigorous as it needs to be, or the wort was held hot for too long in the brewhouse.

The presence of phenolic (Bandaid/medicinal flavor) is most likely indicative of having sanitation or ingredient issues.

The presence of excessive grainy or harsh, wet paper or cardboard character is indicative that the beer is either old, or was packaged with high oxygen levels. As someone pointed out in the last blog, this applies primarily to fresh beers. In high strength beers that are brewed for aging, like Imperial Stouts, Barley Wines, etc., the aging and oxidation can create complex flavors that are highly desirable. But still, the aging process must be controlled by holding the beer at the right temperatures to avoid the development of excessively harsh flavors.

3. Creativity: This is a big part of what is going to make or break brewers that are just now getting started. There are so many brewers out there now, each brewery has to have a unique product and message in order to stand out in the crowd. This being said, if you don’t have the first two elements locked down, creativity and uniqueness won’t mean squat. And be mindful of flavor balance. More hops or more spice, for example, isn’t always better. Learning how to get proper balance of flavors in your beer requires skill and experience.

So what’s a brewer to do? Here are my recommendations for brewers that are just starting out:

1. Every single brewery should have, at the very least, lab equipment that includes a pH meter, a hydrometer, and a microscope that is capable of viewing yeast and bacteria.

A pH meter is used to check brewing water pH (critical for proper and consistent mashing), wort pH and beer pH (changes in beer pH can indicate the presence of acid-producing beer spoiling bacteria). pH meters are also critical in wastewater operations. Most municipalities that receive waste streams from a brewery require a certain pH range for that liquid, so brewers need to be able to measure and adjust the pH of their waste streams.

A hydrometer is a floating, calibrated glass or plastic spindle that is used to measure the specific gravity (or density compared to water) of the wort, which refers to the sugar content of the wort. It’s critical to understand wort specific gravities throughout the brewhouse and fermentation process. This tells the brewer that the targets in the brewhouse are being met, and that fermentation (which causes a reduction of sugar content) is occurring at the proper rate. There is an instrument called a refractometer which also measures the density, but be aware that this instrument, while easier to use, won’t provide accurate numbers in beer (with alcohol). But for the brewhouse gravity checks a refractometer is a great tool.

A microscope is critical for viewing brewers’ yeast. Brewers need to check every fermentation as it progresses for yeast viability and cell counts. This involves taking a sample of fermenting beer, or the yeast, and putting it on a special slide called a hemocytometer. The hemocytometer is equipped with gridlines that assist with counting the cells-important to know as fermentation progresses-should see a 3-5 fold increase in yeast at the height of fermentation. In addition, staining the yeast with methylene blue, trypan blue or methylene violet will allow the brewer to count dead yeast cells vs. live, healthy cells. Yeast viability should be be in the 90+% range if you hope to re-use the yeast with good results.

2. At the second level, brewers should really consider investing in a shaker table, malt sieve screens, an analytical balance and a Dissolved Oxygen Meter.

The shaker table holds Erlenmeyer flasks and is used to agitate samples of wort from each brew in the presence of a lot of yeast. The beer in the flasks will completely ferment out within 24 hours, and by measuring the gravity after this process, the brewer will know where exactly the fermentation should finish in the production fermentor. This is called a “forced fermentation” or “attenuation limit” test. In my opinion, this is one of the most critical quality checks a brewer can do, since chilling a tank of beer that still has residual sugar in it, even though the fermentation appears “done”, can result in a sweeter beer that is very susceptible to microbial spoilage. Don’t ever stop a fermentation before the fermentable sugars are consumed, it’s a recipe for disaster. This test can also be done with a lower price tag using an Erlenmeyer flask of fermenting beer placed on a stir plate with a magnetic stir bar.

A malt sieve shaker is set of circular screens with varying mesh sizes that are stacked on top of each other, from coarsest (most open) sieve at the top to a fine mesh sieve on the bottom. Milled malt is placed on the top screen, and the stack is shaken. As the particles of millled malt fall through the screens, they are held back on a particular screen with a mesh size too small to allow the piece to fall through. Using a scale or analytical balance to measure the amount of milled malt retained on each screen allows the brewer to gauge the performance and consistency of the malt milling operation. There are guidelines for the percentage of total grain that should be held on each screen to optimize extraction of sugars and also get good straining of clear wort from the spent grain. Several quality, taste and efficiency issues arise from having too much coarse material in the milled malt, or too much fine/powder material.

The Dissolved Oxygen (DO) meter is the most costly piece of equipment mentioned so far (usually $3000-$10,000), but is critical to ensure low dissolved oxygen levels in the fermented beer. Oxidation reactions create excessively harsh, papery and grainy flavors, and also a very rapid loss of hop character. A brewer who knows that their process is keeping the beer free of oxygen can be assured the beer will survive better in the treatment it gets out in the trade.

Understand that many of these pieces of equipment can be purchased for very reasonable prices, especially if the brewer is willing to shop around and buy used equipment on eBay or Craigslist.

Most small brewers don’t have the resources to purchase the more expensive equipment used to measure IBUs and alcohol. But there are several companies that provide analytical services, and I highly recommend using them on a regular basis. Small brewers have to rely on calculations and estimates to list abv and IBU levels. Using an analytical service can verify those numbers and make them more accurate, as well as help ensure consistency from batch to batch.

3. A formal sensory program is a must! Sitting at the bar and having a glass of beer does not constitute a sensory program. Sensory programs require formal tasting of the in-progress beer and finished beer to ensure the flavors are consistent and desirable. I recommend tasting daily at a minimum: brewing water, samples from the fermentor (a sniff test is fine here), beer that is ready to package, and packaged beer. Also, a museum stock of packaged beer should be held cold and at room temperature and tasted on a regular basis to ensure the beer isn’t going stale too quickly. A consistent and thorough tasting program helps ensure beer flavor consistency and also helps catch problems very early, when they are easier to fix. And keep records!

4. Don’t accept poor quality ingredients. Have a program to select what you want to use (this refers in particular to hops), and evaluate your ingredients as they come in to make sure they are of proper quality. This is tough for a brewer that is just starting out, because often there is no money available to forward contract the hops or the malt. Just be aware that there are some sub-par ingredients out there, don’t succomb to financial or production requirement pressure to use them if you can avoid it.

5. Have a basic microbiological testing program. There are many ways to do this, but have a formal program to either streak agar plates with samples of wort and beer, or some other method that will tell you if your process is sanitary enough to ensure no spoiled beer. Spoiled beer will turn off beer drinkers very quickly, and most customers won’t come back for another try. And people on the beer internet sites love to spread the word about infected beer.

6. Don’t release sub-par beer. If the beer is spoiled, or has off-flavors, please bite the bullet and dump it. Take the financial hit, because in the long-term, it will save the company’s reputation. Learn something from the experience and move on.

7. Understand beer styles and how to brew them. This doesn’t necessarily mean be part of the “style police” and brew everything strictly to style. But it does help to understand the established styles so you can use them as a basis for your beer and develop well crafted variations on them.

8. For goodness sake, if you are a brewery owner, hire a trained and/or educated brewer to run your operation. Don’t skimp on this so very important part of the business. There is no substitute for experience, but a young person who has just graduated from brewing school (and there are many excellent ones across the country) will be able to understand the brewing process on a commercial brewing scale much more effectively than someone who has only brewed several batches of homebrew. This really is critical. Get someone who on board understands the science behind brewing. A brewing school graduate will demonstrate both passion for the craft and the ability to think critically about the processes and troubleshooting.

9. Rely on the industry for help and advice. The Brewers Association out of Boulder is a wonderful organization for craft brewers. It doesn’t cost much to join, and there are many ways you can ask questions, and get answers from some of the smartest, most experienced brewers in the country. The Master Brewers Association of America is a technical association that has been in existence for over 100 years. And though historically they have been the technical organization for large brewers, they are now also focused on craft brewing. There are regional districts of the Master Brewers all over the country, and it costs typically less than $150/year to join. The district meetings are a great place to network and learn from more experienced brewers, and the annual conference is a nationwide event that presents some of the best brewing technical information I have experienced. As a third option, this industry is still young, and there still a strong sense of brotherhood and camaraderie among craft brewers, and most of the local brewers are likely willing to help a startup brewery with quality or equipment issues and advice. And finally, websites like pro brewer.com have excellent forums where brewers can ask questions and get great answers.

10. Be humble when praised, and respond quickly to complaints. Nothing can salvage a brewer’s reputation quicker than providing a quick response to a customer who has a complaint about the beer. Make a sincere effort to make good on the issue, either by replacing the beer or sending a shirt, hat, or logo glass. Ignoring complaints will come back to hurt the business. More people spread the word about poor experiences with beer and breweries than those who have had enjoyable experiences. And when receiving praise, don’t get a big head. Know that a serious quality issue, infection, bad batch, whatever, is lurking just around the corner. I remember Dan Carey of New Glarus once saying: “There are 2 kinds of brewers: brewers that have had infection issues, and brewers who haven’t had infection issues, yet“. True words.

11. Focus 100% on cleanliness and sanitation. Experienced brewers know this, and often (semi) jokingly call themselves janitors, because 75% of their job is cleaning, scrubbing, and sanitizing. Wort, being 12-25% sugar, is extremely susceptible to unwanted bacterial or wild yeast spoilage. And beer is only a bit more resistant. An unclean brewery cannot produce consistent beer without off flavors.

And now it is time for me to get off my soapbox, at least for a few days!