In my fraternity days, there was a constant fear of beer (typically kegged but also bottled) getting "skunked" as a result of warming up and cooling down too many times, possibly even once.

Do non-extreme temperature changes such as moving a beer back and forth from a counter to a refrigerator cause perceptible changes to beer? If not, what about more extreme changes, such as sitting in the bed of a truck or a trunk? I'm aware that light has a degrading affect on it's own, so let's assume this beer is in a keg or a light-proof box.

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    I don't know enough to answer, but will add this observation: The old legend that "Cold, Warm, Cold Again" skunks beer CAN'T be true: Coors is "Shipped Cold from the Rockies," or some such nonsense, but you can buy it warm in the store. And in numerous observations, I've found that making it cold again makes it no more gross than it always is. – Jaydles Jan 21 '14 at 21:19
up vote 19 down vote accepted

In short, no.

As explained by George de Piro, a biochemist and Brewmaster of C. H. Evans Brewing Company—

When light hits beer, it provides the energy necessary to drive a reaction that transforms the iso-alpha-acids into 3-methyl-2-butene-1-thiol. The “thiol” part of that somewhat cumbersome name indicates that there is sulfur present. Sulfur compounds often have strong, offensive aromas. Some musteline animals, like skunks, have evolved the ability to produce this chemical, and use it for self-defense. [...] This photochemical reaction is the only cause of skunked beer. Warm storage, while damaging to the flavor of beer, does not skunk it. Cycling the temperature of beer from warm to cold and back again is also not implicated. Storing beer in the dark is the simple way to prevent skunking.

It's actually pretty amazing how quickly this reaction can happen! From the same article,

The photochemical reaction that skunks beer occurs very quickly; a well-hopped beer in clear glass can become noticeably offensive with just 30 seconds of exposure to sunshine.

To wrap it up,

Since light is an essential ingredient in the skunking process, beers packaged in kegs, cans, and opaque bottles cannot be skunked.

Here's the most detailed experiment I could find—The Impact of Lightstruck and Stale Character in Beers on their Perceived Quality: A Consumer Study.

Slight temperature changes will not spoil your beer. Large temperature changes will.

The "skunky" beer is actually lightstruck. This is exactly what it says: the beer has been damaged by light, such as sunlight or florescent light. When UV lights penetrate the glass of a beer bottle, they mess with the chemical makeup of some acids produced by the hops. The result is a new compound called methyl mercaptan, which is one of the components of the defense mechanisms found in the skunk.

This is prevented by packaging beer in brown bottles, which is better protected from UV rays. Unfortunately, this lets those green rays get in, which makes sense as to why some beers are served with lime: it keeps away the "skunky" smell for a while.

In reality, it doesn't take much to spoil your beer. If your beer in a green or clear bottle has not already been spoiled before it got to the store, about a minute's worth of exposure to the sun would do it.

  • Can you build on the temperature part? How hot can my beer get before it's ruined? – Brian Nickel Jan 22 '14 at 18:25
  • Well, I haven't tested it, but I can tell you that doing drastic like dumping it in liquid nitrogen and then leaving it out in the sun for a couple days would ruin it. – user90 Jan 22 '14 at 21:10
  • I'm confused. Your opening paragraph is completely unsupported by the rest of your post. I'd posit that temperature changes do not spoil beer, but you start out saying it does... and then go on to talk about how light affects beer. I think that first paragraph may be wrong, but there's little in the rest of the text to say so one way or the other. – Robert Cartaino Jan 23 '14 at 0:59

I've hauled everything that comes out of the brewery in Golden, CO. None of it was hauled in a reefer trailer. All in a dry van. Some loads sat in 95 degrees for days before delivery. Just saying.

Actually beers from Anheiser Busch have preservatives in them witch it can get warm or cold or whatever. Coors beer products on the other hand do not have preservatives and have to stay cold all the time. I worked for Coors Distributing and we kept the beer cold on the train to the warehouse to the trucks, to the customer. All refrigerated.the whole way. That is all I know that i was told..

I have read a lot on this and keep finding it's a myth. I am a raging alchy and drink beer all the time. I get this bud from Walgreen's and they have a horrible stocking procedure, I know for sure the beer is cold, then they let it get warm, then refridge it (the cans are always sweating). It's been 5 times I've drank this bud from them and all the time my stomach kills me from it. I think it, for some reason, creates more gas (lot of foam in my stomach, feeling like I have to burp, but cannot). I drink the same amount of beer on any given day from a good distributor and have no problems.

Side note to add, the beer also has a lemony taste to it, so I don't know exactly the chemical reaction,but I'm positive that going from cold to room temp, then cold again screws the beer.

Fluctuating temperatures cause oxygenation of your beverage, but only over one or several years. This may spoil your beer, but not "skunk" it.

I have read that wine in wine cellars at around 14-16 degrees celsius last the longest, and that unstable and fluctuating temperatures over many years will spoil your wine by oxygenation. The same would apply for all alcoholic beverages.

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