Why does commercial beer get skunky?

The consensus around here seems to be "the longer you wait the better it gets".

Is there a cut-off, because commercial beer like Sam Adams and Budweiser follow a born-on date?

Also, commercial beer will go bad if you get them cold, warm and then cold again. Do ales do the same thing?

I was just reminded of bad beer when this came in the mail. About six months ago I got a bad sixer and SWMBO sent them an email.

Commercial beers gets skunked if its packaged in green or clear bottles, they don't use a light-stable hop extract, and the bottles are exposed to sunlight or fluorescent light. The same thing happens with homebrew.

How well beers age is pretty much a factor of alcohol content and ingredients. High alcohol beers tend to age much better than low-alcohol beers. Most wheat beers don't age particularly well. Hop-forward beers may or may not age well, but much of the hop character and bitterness is lost with extended aging. Again, there is little difference between homebrew and commercial beers. What does impair commercial products is abuse during shipping and storage - at home, we can control these conditions, but we have no influence over how commercial beers are treated.

I have always wondered the same thing. A lot of the times I will go to a store where you can buy a six pack or singles and drink them there, the beer has been on the shelf for the past 4 months, I think that might cause some off flavors.... but what do I know



well.... I know to check dates on the bottles or box now

I think the warming/cooling thing is a myth. Bud Light might not be able to withstand it well, but any decent commercial beer and homebrew shouldn't be a problem.

impatient said:

Also, commercial beer will go bad if you get them cold, warm and then cold again.

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I've heard this, but I wonder if it is really true. Anyone know?

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That is really cool

I've been lambasted in the past about my opinions on "skunked" beer. I don't think skunking is as common as people want to believe. Sometimes, beer is is just not as good as we think it should be, so we invent a reason for it. I'm not saying that skunking does not happen, just that it is the go to excuse for crappy beer.

There's a Basic Brewing Video where they leave some SNPA in a clear glass in the sun. After 45 minutes, the beer was undrinkable!

taylornate said:

I've heard this, but I wonder if it is really true. Anyone know?



That is really cool

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From what I have read in the past, extreme temp differences (especially damaging are excessively warm temps) over a short period of time will degrade the quality of many brews. I ran across a site a while back were a guy subjected beers to all sorts of abuse and reported the results...I'll have to see if I can find it.

944play said:

There's a Basic Brewing Video where they leave some SNPA in a clear glass in the sun. After 45 minutes, the beer was undrinkable!

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But why would anyone do that!!?? I can do the same with a pound of pork sausages and tell anyone it is a bad idea.

brewt00l said:

From what I have read in the past, extreme temp differences (especially damaging are excessively warm temps) over a short period of time will degrade the quality of many brews. I ran across a site a while back were a guy subjected beers to all sorts of abuse and reported the results...I'll have to see if I can find it.

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I'm not that interested in anything extreme. I just want to know if you buy chilled beer and let it warm to room temp before chilling it again if it really has any impact.

I like Molson Canadian and Molson Export, but when I get Molson Golden in bottles OR cans, it has a skunkiness to it. Moosehead is another skunky beer. In both the Golden and the Moosehead, I buy it because I like the skunk. BTW, both beers come in green bottles. Anyways, just my $.02.

Totally aside from the skunking issue, I would frame that check, not deposit it :rockin:

taylornate said:

I'm not that interested in anything extreme. I just want to know if you buy chilled beer and let it warm to room temp before chilling it again if it really has any impact.

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You might be able to detect a difference if you did a comparison with one that was optimally handled but it's not going to ruin the beer.

However, it's always an excellent excuse to drink everything that can't fit in the fridge!

I was out with some friends at a local "College *******" bar, and one of us ordered a Newcastle in the bottle. The second that the bartender cracked that sucker opened, a horrible stench filled the air, so bad that people further down the bar jumped and gagged. You could almost see a cloud of noxious vapour rise from the dewy bottle.

The bartender offered to replace the Newcastle with something else, as it was the last bottle. Instead, my idiot friend drank that nasty crap. His reason:

"It's still a Newcastle!"

Newcastle is crap. The BMC of the UK.

KayaBrew said:

I like Molson Canadian and Molson Export, but when I get Molson Golden in bottles OR cans, it has a skunkiness to it. Moosehead is another skunky beer. In both the Golden and the Moosehead, I buy it because I like the skunk. BTW, both beers come in green bottles. Anyways, just my $.02.

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I gave up on Molson Golden because I started getting more and more that tasted skunky... This was always my favorite.. I've switched to Canadian and have been very happy.

Laughing_Gnome_Invisible said:

I've been lambasted in the past about my opinions on "skunked" beer. I don't think skunking is as common as people want to believe. Sometimes, beer is is just not as good as we think it should be, so we invent a reason for it. I'm not saying that skunking does not happen, just that it is the go to excuse for crappy beer.

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Well, I drink their Octoberfest every year. This time it was awful. They said in the letter, that this is common because they don't use preservatives and mishandling during shipment is the most likely cause.

enderwig said:

Totally aside from the skunking issue, I would frame that check, not deposit it :rockin:

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Yes, I plan to keep it. I wouldn't even have it if is wasn't for SWMBO.
I would have just wrote it off.

KayaBrew said:

Newcastle is crap. The BMC of the UK.

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I just had my first two the other day and I thought they were pretty horrible. I assume there are good english brown ales...?

Regarding skunking, if room temp/cold/room temp will skunk a beer then why doesn't cold crashing skunk a homebrew? You ferment at 65, chill it for a few days then go to 70 degrees to bottle condition.

kendrid said:

I just had my first two the other day and I thought they were pretty horrible. I assume there are good english brown ales...?

Regarding skunking, if room temp/cold/room temp will skunk a beer then why doesn't cold crashing skunk a homebrew? You ferment at 65, chill it for a few days then go to 70 degrees to bottle condition.

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Temperature changes shouldn't cause skunkiness, but they could contribute to staling. Skunkiness requires exposure to sunlight or fluorescent light.

From How To Brew:

Skunky
Skunky or cat-musk aromas in beer are caused by photochemical reactions of the isomerized hop compounds. The wavelengths of light that cause the skunky smell are the blue wavelengths and the ultraviolet. Brown glass bottles effectively screen out these wavelengths, but green bottles do not. Skunkiness will result in beers if the beer is left in direct sunlight or stored under fluorescent lights as in supermarkets. In beers which use pre-isomerized hop extract and very little flavoring hop additions, the beer will be fairly immune to damage from ultraviolet light.

For the question on letting a commercial beer warm to room temp after it is chilled, then chilling it again, I don't think its a problem. I've had times when I couldn't get some beer in the fridge for a few hours. Just don't leave it sitting in a hot car in the middle of a South Carolina summer and you will be fine.

impatient said:

Well, I drink their Octoberfest every year. This time it was awful. They said in the letter, that this is common because they don't use preservatives and mishandling during shipment is the most likely cause.

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You have a good point. I have had to revise my opinion since watching this video...... However, I think I can still defend my case.......Bear in mind that I do not buy a lot of commercial beer in the US. I brew so that I can drink the English ales that I am accustomed to..... Frankly I think it is probably more of a US problem regarding distributors and outlets that do not understand how to look after their merchandise. I never tasted a skunked beer in the UK, and I'm guessing you wouldn't in Germany either.

Further to that point, yes, Newcastle Brown these days is BMC. 35 years ago it was a good pint, but in that 35 years of buying beer in Europe, I never had a skunked one. Declined quality yes, skunked, no.

So, to clarify my new position on skunked beer:- It is most likely a problem specific to the US and it's poorly educated distributors.

[QUOTE I never tasted a skunked beer in the UK, and I'm guessing you wouldn't in Germany either. [/QUOTE]


According to the current moral panic it seems we're so quick to neck as much as possible in great Bacchanalia binges that it doesn't have time enough on the shelves to go a bit off. Either that or cos we never get any bloody sun.

+1 on keeping that check. In 20 years we'll see you getting it appraised for much more than $9 on Antique Roadshow.

Have any of you had a homebrew get skunky after several hot/cold temp changes?

I told my BIL he should get a couple of 5 gallon kegs from a local brewery for his wedding. He insists that picking up the kegs cold, then driving for 4 hours to the wedding site, thus allowing them to get warm, will ruin the beer. I can't say for sure if I think he's right or wrong.

You should probably alter that image to take the numbers of the bottom out of the picture. It's not cool to have that type of info out on the WWW.. My opinion, take it for what it's worth.

Dagatris said:

Have any of you had a homebrew get skunky after several hot/cold temp changes?

I told my BIL he should get a couple of 5 gallon kegs from a local brewery for his wedding. He insists that picking up the kegs cold, then driving for 4 hours to the wedding site, thus allowing them to get warm, will ruin the beer. I can't say for sure if I think he's right or wrong.

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Again, beer cannot skunk from temperature changes. There might be some sort of off flavor if you let your beer get to 90 degrees or higher for an extended time and then cool it down again, but that is pretty much the case with letting any beer get that warm.

As for skunking due to light, it can be detectable in as little as a minute, so be careful with green bottles and the like. As for the poster who mentionted skunk flavor in a can, I can't imagine how you get beer in a can that tastes skunked. Unless it is being exposed to light before canning, it is likely a different off flavor.

when I get growlers of Magic Hat, Otter Creek or Vt. Brew Co. and drive 6.5 - 7 hrs home to Delaware I have never had a problem even in the trunk on a hot summer day. They taste the exact same as when I get slanty from the free samples...thanks Magic Hat I <3 you guys!!!