Tag Archives: oxidation

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?

I fell into an interesting discussion on Facebook yesterday that was started by Gary Spedding, a long time colleague who runs Brewing and Distilling Analytical Services, a company in Kentucky that can do complete analysis on beer, spirits, and other beverages.
Gary referenced this Article and also a talk from Michael Lewis, my brewing professor at UC Davis back in the 1980’s, at this year’s Craft Brewers Conference in Washington, DC, that was critical of craft beer quality in general.

Michael Lewis’ talk at the CBC was quite provocative, which I’m sure was his intent. He scolded the craft brewing community for being smug in our success, and cited that most craft brewers don’t have the wherewithal to really deal with important quality issues, especially those that could hurt the consumer. And when compared to large and/or well established brewers across the world, he is absolutely right. Now to be clear, there’s no microorganism that can grow in beer that can make people sick, which is just one reason why it is such an amazing drink. But his examples included bursting bottles, which some of us have had to deal with, and also the rampant use of herbs, spices, foods, and other botanicals in beers. Brewers sometimes don’t list their unusual ingredients that could potentially make some people sick. And he has a point. With the exception of Sierra Nevada, New Belgium, and some of the other brewers who have graduated from microbrewery status to “Regional Craft Brewery”, most of the smaller brewers in the USA have very rudimentary labs, don’t really analyze their beers, and don’t necessarily do all the due diligence required when adding an an unusual ingredient to their beers.

As Gary Spedding points out, the TTB, which governs brewers and approves formulations (recipes) for beer, especially when the beers include unusual processes or ingredients, is a shrinking agency. Once under the umbrella of the old Bureau of Alcohol, Tobacco and Firearms, the TTB (Tax and Trade Bureau) split off at some point after 9/11, and currently has a very small staff that cannot handle the sheer volume of brewers’ formula approvals that come across their desks. And many smaller brewers, especially those that only sell their beer at their pubs, taste rooms, or just locally, don’t even bother with TTB approval, as long as they have local or state label approval. So there are a lot of beers out there that have ingredients not reviewed by the TTB, which I find a bit unnerving.

So what is a quality beer? It’s different depending on who you ask, which is part of the problem. Some people view quality as pushing the envelope, being creative, and brewing unique, groundbreaking beers. Some, who I refer to as the “style police”, look at a beer with an eye towards accepted style guidelines, and knock a beer if it doesn’t conform to certain style parameters, such as bitterness, sweetness or dryness, malt character, hop intensity and the like. Others look at consistency in beers-does the beer taste the same from batch to batch? I can tell you that this is very important for us at Stone-we want people who are buying a six-pack or case of Stone IPA to know what they are getting, and to get what they expect. A lot of people don’t think American Lagers have any quality, and to me that is a big mistake. Just because someone doesn’t like the flavor of the beer, or the fact it is brewed with cereal grains, doesn’t mean that the beer lacks quality. The consistent flavor of these beers with so little malt and hops flavor is actually quite an amazing technical feat, and it takes a high level of talent and skill to pull it off.

To me, quality means all of the above to a certain extent, plus whether the beer has a proper balance of flavors, and also the absence of off flavors, such as diacetyl (butter), acetaldehyde (green apple, pumpkin seed), phenolic (band-aid), and oxidation/age (cardboard/harsh/stale). Let’s look at a few of these off-flavors in more detail:

Diacetyl:  There are people that say buttery diacetyl is acceptable in some styles, and I call BS on that. In my opinion that’s a cop out. Perhaps that’s because I learned from Dr. Michael Lewis, and Anheuser-Busch, but I cannot drink a beer if it has even the slightest trace of diacetyl. Diacetyl is formed by yeast during fermentation, and is taken up by again and metabolized by yeast during aging, so the resulting beer should have none. Diacetyl in beer can be a result of a fermentation issue, unhealthy yeast, rushing the beer through aging, or in some cases, a bacterial infection. And I cannot stand the movie theatre buttered popcorn flavor in beer that results from diacetyl. When I worked at San Andreas Brewing Company, we used a dry yeast strain (this was before Wyeast and White Labs) and occasionally, one of our flagship beers, Seismic Ale, would throw some diacetyl.  I hated it when this happened, but many customers who came into the pub absolutely loved it. It was quite confounding and frustrating, but we still worked hard to ensure the beer didn’t have diacetyl.

Acetaldehyde is another flavor that results from fermentation issues, and is present in beer either because the beer hasn’t been aged long enough, or if the yeast health is poor, the yeast cells die and burst, releasing this flavor into the beer. In any event, acetaldehyde is hard flavor to discern at lower levels, and is one of the hardest off-flavors to detect and also fix. There is a common misperception that the green apple ester that some people use to describe Budweiser is acetaldehyde. I’ve heard this from very experienced, knowlegable brewing educators, and it is absolutely wrong. Budweiser has the lowest measured acetaldehyde levels of any major American lager brewer, the green apple ester is something else, and this exemplifies some of the confusion about this off-flavor. Not to name any names, but there is one lager brewer who operates in this country whose beer has definite acetaldehyde-and I think it’s a characteristic of their yeast strain, because it’s very consistent in their beers. So is this an off-flavor? To them perhaps not, but I find it unpalatable.

Oxidation: The other off flavor that drives me crazy is excessive age. This exhibits itself as grainy flavors, harsh or cardboard/wet paper flavors in beer. As craft brewers have become better educated, I’ve seen a drastic reduction in instances of diacetyl or acetaldehyde, but graininess is still something I see a lot, and to me it’s a major flavor flaw. People who drink a lot of import beers have become accustomed to this flavor, and may even find it desirable in some cases. And craft brewers are among the worst offenders of beer freshness. Many assign 6 month to one year code dates on their beers, without really testing, let alone considering, what the beer will taste like after that much time sitting on a dusty shelf. I can tell you, beer with any hop character is going to lose the hops within a couple of months, and will be harsh, grainy and undrinkable very soon after that. This oxidation character can be controlled to a certain extent by keeping beer free of oxygen post-fermentation and during packaging, but many small brewers lack the technical skill to measure dissolved oxygen, let alone control it during packaging or fixing the situation when oxygen levels are high.

Beer drinkers, by and large, are not familiar enough yet with these off flavors to make an accurate judgement as to whether the beers have quality issues or not. And that is because large brewers, who many people grew up with, are technically skilled enough to prevent off flavors in their beers. So people aren’t used to tasting beers with off flavors, and often can’t identify off flavors when they are present. And so they base quality on other things, like uniqueness, hoppiness, maltiness, unique sour character, or simply whether they like the beer or not. However, at some point, as the less experienced consumers become better educated about beer, low quality beers with high levels of off flavors are going to turn some people off, and that could have a negative effect on the whole industry,

Here’s the real issue: With so many breweries popping up right now, which in general is a good thing and is very exciting to me, there are some breweries that have brewers who lack the education, experience, or sensory acumen to ensure consistency and prevention of off flavors in their beers. I can’t count how many small breweries I’ve visited that don’t even have a microscope or pH meter in their facility, and this makes me nervous. Brewers that believe they can judge their beer’s quality by sensory analysis alone are missing the boat, there are some basics regarding Quality Assurance that absolutely must be adhered to. I remember seeing a presentation by Ruth Martin at Sierra Nevada, where she outlined what a craft brewer’s quality regimen should be as they grow and expand their distribution. It was a very gratifying talk for me, because we had been growing our quality program very closely to what Ruth recommended, and we continue to so so.

I remember, many years ago, I walked into a brewpub, and talked to the brewer, who had just been hired on. He had been a line cook in the establishment’s restaurant, and when the previous brewer left, they gave him the brewer’s position, despite the fact he had no experience brewing beer, or any technical education at all. And this situation made me very upset. First, it annoys me that some brewery owners see so little value in brewing experience and will hire people that don’t know what they are doing. A brewer has to be many things, and recipe creator is just a small part of the job. If the brewer doesn’t have a good understanding of the importance of cleanliness and sanitation, off-flavors, how they are caused and what can be done to remedy them, brewery safety, yeast management, etc. the beer is going to suffer. Secondly, this poor kid had no clue about brewing, beer styles, ingredients, and what makes a quality beer. He was put in a position to fail, and that angered me.

Unfortunately, as the craft brewing industry is enjoying a nice boom right now, a lot of people are starting breweries that just don’t understand how critical it is to have someone who knows how to brew at the helm. And too many people are starting breweries because they have money and think it would be cool, vs. having a real passion for beer and the art and science of brewing. And I think that’s sad, and potentially damaging to the industry.