Tuesday, July 22, 2008

Can You Take the Heat?

Possibly the most widely circulated and believed myth surrounding beer is with regard to temperature. Most people believe that beer must be kept refrigerated always, and that once allowed to warm to room temperature, it can never be cooled again. Room temperature would essentially spoil the beer, much the same way as any dairy product would spoil.

Except that beer is not a dairy product. Fluctuations in ambient temperature do not adversely affect beer any more than any other foodstuff. Beer is remarkably delicate and yet astonishingly durable at the same time, and the common room temperature is in no way harmful to either its flavors or storage life in the short term. Beer bought from the warm shelves is no different than what is retrieved from the cooler, and may be the exact same beer merely a few hours removed.

So how much heat is too much heat? Is beer something you can leave in the car on a hot summer afternoon? For how long? Can it be stored indefinitely at room temperature? And what is “room temperature,” anyway? What counts as “hot” in Minneapolis is certainly not the same as what is experienced along the Texas/Mexico border.

Beer belongs to a special subset of our food supply that are living things. More precisely, beer is several billion living things—we call them yeast. Like most living things, yeast have a temperature range in which they are happy and comfortable, and a range in which they fuss about, complain and eventually die. We forget that beer is less a beverage and more of a microenvironment, depending entirely on your perspective.

Basically, if you are comfortable, so is your beer. During fermentation, most yeast strains prefer temperatures between 55°F and 75°F (or 45°F and 55°F, if you happen to be lager yeast). These ranges qualify as “room temperature” for most anywhere, and any of us will generally be comfortable in these environments. Over 75°F and yeast begin to produce some quite nasty byproducts, lending off-flavors to the finished product. Much over 100°F and yeast start to die, so their comfort range is pretty close to that of any other organism. But all this is for brewing; what about the packaged beer on the shelf?

For most beers the commercial product is inert, the yeast having died off long ago due to lack of food, filtered out or killed through a variety of pasteurization processes. What is left in the bottle is a mix of sugars, proteins, alcohols, oils and trace other chemicals (plus water, naturally). None of these compounds is active, so the only thing left for them to do is to degrade over time.

This is where the temperature is a factor. Heat accelerates chemical reactions, making the natural breakdown processes of large molecules into small molecules happen more quickly than they would otherwise. What does this mean for beer? Simply this: it ages faster. A general rule of thumb for the brewing industry is that beer stored at 100°F for one week tastes as old as beer stored at 70°F for two months, or as old as beer stored at 40°F for one year.

Time is as much a factor in beer quality as is its ambient temperature. Storing beer in the trunk of your car during summer months is obviously a bad choice—unless it is just for that half-hour transporting it from the store. Fluctuations in temperature are not ideal but are certainly not disastrously harmful to the beer, no more than they are harmful to your own body. A good guideline is to never leave your beer anywhere that you would not leave your dog (and for the same reasons).

Beer stored at room temperature is never bad, merely not chilled... unless it has been at room temperature for many, many months. In this case, the fault is not with the environment but with the retail establishment itself. Do not blame the storage temperature for what is actually a neglectful vendor failing to sell their product in a timely fashion.


Anonymous said...

I mostly disagree. Beer is very sensitive to temperature. Each time the temperature rises, the beer oxidizes. It could be a little every day, or all at once. Most beers are damaged before they even reach the store, being shipped, stored, and or delivered with little regard to temperature. Have you ever seen an unrefrigerated delivery truck in the middle of summer? Of course you have.
The smaller the container, the larger the percentage of air-to-beer. So, kegs hold up best, and 12oz bottles are most sensitive. A larger container is inherently more stable and it takes a longer time to change temperature.
If the beer is live, the yeast are dormant from 32-50 degrees. Below freezing, yeast cell walls rupture and above 50 yeast become active, expiring more quickly with higher temperatures.
A pale, hoppy beer is most sensitive- pale malts contain more oxygen than roasted malts and the polyphenols in hops chemically degrade with oxidation. A dark malty beer can hide these effects better, but they are still there.
A beer kept at a STEADY temperature between 35-50 degrees holds up best. The pressure in the bottle keeps beer about 1.5 degrees higher than ambient, so beer does not reach freezing temperature until about 30.5 degrees. When it does, it spoils immediately, losing its aroma and mouthfeel, finishing on the back of the tongue or throat. The beer declines daily and sourness increases daily.
With either heat or freezing, you may notice protein conglomeration in the bottle of unfiltered beers, otherwise known as fluffy floaters. Don't buy it!
A beer that reaches 100 degrees for one second gets poured down the drain! Are you kidding? Yuck!

I have done controlled experiments with a case of Lagunitas Maximus with several other tasters. All beers were from the same case and subjected to different temperatures over the course of 3 days and tasted immediately following as well as five days later. All served at 38 degrees. The control beer was kept at 38 degrees. Three beers were subjected to freezing; 30, 28, and 26 degrees and immediately returned to 38 degrees- each one noticeably worse. One beer kept in ice water, which is 33.1 degrees, but the actual beer temp was 34.5 degrees. There was no discernible difference between it and the control. One beer was refrigerated at night and room temp during the day for 3 days- had some papery and sour notes. One beer left outside in the dark, reached 91, 72, and 58 in the day and 60 at night- smelled bad, malty and sour notes- undrinkable 5 days later. Finally, one beer was kept inside in the window- smelled horrid, skunked for sure, down the drain! All tasters came to the same conclusions, but individual tolerances for drinkability varied.

I am so discouraged with improper handling that I now only buy bottled beer when the weather is right- that's between 35 and 50 degrees from the time the beer was bottled to the time it reaches the store- a small window in the year. Although a recently bottled beer is preferable(unless it tastes like butterscotch), it makes little difference in freshness if it is spoiled in the warehouse or delivery truck. There's an expensive super-hopped strong beer, let's call it Hype Scam, that comes out every January. For the last three years it has been "frozen" before it reached our stores. It's a good beer, at least it was in 2009, when the temperature cooperated.

Do your own experiment, if you're not convinced, but make sure you buy your case of beer in good beer weather or it may already be spoiled!

Anonymous said...

As a craft brewer, I was appalled at this article. Beer has 3 natural enemies- HEAT, light and oxygen. Some beers will cope with heat better than others (like Bud, Coors, etc) but micro brews or craft brews that are not pasteurized are a different story. Sure, they aren't dairy products, but there are lactobacillus, brettanomyces and other bacterias that are kept dormant by refrigeration that may have entered the beer during the brewing/packaging process. Allowing non-pasteurized beer to sit at room temperature allows these yeasts and bacterias to wake up causing off flavors and possibly explosive beer.

In the end, if you store beer warm, the best case scenario is that it WILL NOT taste right. Also, It may not even be drinkable due to foaming issues but even worse yet, drinking non-pasteurized beer that has been stored warm can cause digestive issues such as nausea or diarrhea.

Do yourselves a favor and store your beer upright and between 30 and 40 degrees Fahrenheit.

Marcus Fillion said...

Very interesting , thank you. Do you refrigerate your beer rooms then? I'm new to craft beer, and I thought it would be acceptable to store them in a "cool" location(~50*). If that's changing the taste at all, though, I'd start storing them differently. | http://adgemisrefrigeration.com.au

Anonymous said...

Thanks to those who commented, this article is quite misleading/inaccurate and yet the comments have saved it. Nice job folk cheers!

Anonymous said...

"Allowing non-pasteurized beer to sit at room temperature allows these yeasts and bacterias to wake up causing off flavors and possibly explosive beer."
This person is confused and forgets that beer saved humanity by giving drinkable beverages that were free from dangerous bacteria.
Think on the original IPA stored in wooden barrels and shipped from England to India.
If anyone can find a credible reference and a scientific explanation on what warm storage does to beer and what off flavors are created, please post. I've been looking for a while and found nothing. Even the generally accepted report that aromatics from dry hopping dissipates is something that I have yet to find scientific documentation (but I still believe it to be true). However, I have had many beers that did just fine with changing temperatures and warm yet dark storage.

Md Shohidul Islam Robin said...

Good post! Would you recommend Cold Room Chiller ?

Sanowar said...

Nice article, thanks for sharing.