How to decode beer freshness dates
January 28, 2006 4:45 PM   Subscribe

Beer freshness dates decoded [more inside]
posted by rxrfrx (17 comments total) 1 user marked this as a favorite
Today's WSJ featured an article (subscription required) about freshness dates on beer. Most beers are marked with a code that somehow corresponds to the date on which they were bottled. Beer that's been stored for more than, say, 5 months at room temperature is probably not worth buying.

Here's some additional decoding information that's featured in the WSJ article, but not in the FPP link:

  • Asahi uses a four-character bottling code. A letter is the month (I is not used, A=Jan;M=Dec), the second two digits are the day, and a digit is the year.
  • The Coors expiration dates are typically 112 days after the date of manufacture.
  • Corona uses a four-character bottling code. A letter is the year (A for 2001 through F for 2006), the second letter is the month (in reverse alphabetical order, L=Jan;A=Dec), and the last two digits are the day.
  • Dos Equis uses a coded bottling date of day, month, year.
  • Foster's is the same as Asahi.
  • Labatt Blue is the same as Asahi.
  • Miller Genuine Draft uses a coded expiration date of month, day, year.
  • Pabst Blue Ribbon uses a coded expiration date of month, day, year.
  • Pacifico is the same as Corona.
  • Sapporo is the same as Asahi.
  • Sol uses a coded bottling date of day, month, year.
  • Tecate is the same as Asahi.

  • posted by rxrfrx at 4:45 PM on January 28, 2006

    I love how pointless the Weekend WSJ is. Nevertheless it's entertaining:

    Too many brews? Goebel Liquor Store in Wichita carries more than 700 beers.

    Holy shit. Considering what the article states, that beer usually has a shelf-life of under nine months (usually a lot less), that means they're having to turn over their entire inventory a couple times a year. Some heavy drinkers down there, eh?
    posted by geoff. at 5:04 PM on January 28, 2006

    There is a much bigger list at but you have to dig the info out of the google cache
    posted by MonkeySaltedNuts at 5:56 PM on January 28, 2006

    How does beer spoil?
    posted by melt away at 6:12 PM on January 28, 2006

    Oxygen gets trapped in the bottle when it's sealed, and the oxygen interacts with the beer in unfavorable ways.
    posted by A dead Quaker at 6:30 PM on January 28, 2006

    According to the faq:

    What does "bottle conditioned" mean? It is beer that has not been pasteurized, and still has live yeast in it. It will continue to age in the bottle, and the character of the beer will change over time. For some kinds of beer this is good, for others it means they will spoil after a while.

    What makes beer go bad? (what it is and why it is bad/skunked.) Bad beer is beer that tastes bad of is spoiled. Beer can and will spoil under certain conditions. Mishandling and old age are the two biggest causes of spoiled beer. Skunked beer refers to beer that has been lightstruck, causing the hops to take on a skunky odor. This is often happens with clear or green bottles, and tends to be prevalent in certain imported beers.

    I'm only wondering about the specifics, although that still doesn't answer what "old age" does to beer.
    posted by melt away at 7:25 PM on January 28, 2006

    Well, more beer spoilage info at New Scientist. Sometimes oxygen is a factor in deteriorating [something] while other times it's a result of light causing breakdown of alpha acids in the hops.
    posted by melt away at 7:35 PM on January 28, 2006

    Well, I don't see Billy Beer on there, so I assume that the six-pack that I have should still taste great!
    posted by horsemuth at 7:49 PM on January 28, 2006

    As an occasional homebrewer, in my experience this "freshness" and "born on" thing is a marketing crock. Last week my wife had a few pale ales that were sitting in storage since 2003 and she said they were awesome. Stouts aren't even good unless they've been aged for a year or so, and they're great even after 3 years. I wonder if the commercial stuff degrades readily. If they want to do something useful, they need to stop bottling in clear bottles... I've had more skunked Coronas than you can shake a skunk at.
    posted by hodyoaten at 11:35 PM on January 28, 2006

    Fantastic post. Fantastic (though brief) thread.
    posted by Kwantsar at 1:25 AM on January 29, 2006

    The delicious Widmer Brothers Hefeweizen that I'm currently enjoying was bottled on "DEC2705". It also says "06:45" above the date but that can't be the time; that would be taking it too far.
    posted by Devils Slide at 2:04 AM on January 29, 2006

    I'm sure the "expiration date" is carefully calculated to be well inside the time it takes to sell the beer.

    Also, I used to keep sun-faded beers I'd find in the bayou in my truck for emergencies. They were fine. As fine as any other light beer.
    posted by atchafalaya at 3:06 AM on January 29, 2006

    What Devils Slide said. You could just buy beer that is open dated, instead of the brands listed above.
    posted by fixedgear at 5:02 AM on January 29, 2006

    hodyoaten, from my occasional homebrew experiences and semi-frequent buying-beer-at-the-store experiences, I think there's multiple factors involved in beer spoilage.

    Temperature is of course a factor, as any reaction will occur more slowly at a lower temperature. I would never keep any beer at room temperature. As soon as my beers have bottle-conditioned, I either keep them in the fridge or in the coolest part of a basement. If I buy beer, it always stays refrigerated. I've never had a skunky homebrew, but that may just be due to my storage routine. However, I do suspect that bottle-conditioned beer will last longer due to the fact that there's live yeast in there for quite a while after bottling.

    Light is another problem, and beer in clear bottles will go bad much faster.

    The other day, someone brought a few leftover bottles of beer to my house (domestic and imported, all in brown bottles) and they were all skunked. They were obviously starting to spoil. I don't know if they were stored in a very warm place or what, but the "freshness date" is certainly not a marketing crock, given the way beer is stored in distribution and at most liquor stores (that is, at room temperature and with strong lighting).
    posted by rxrfrx at 5:45 AM on January 29, 2006

    Excerpted from

    Almost all beer contains hops. Hops give the beer bitterness, and flavor, and aroma.

    The hop compounds that are responsible for making beer bitter are called isomerized alpha-acids. These chemicals, along with sulfur compounds found in beer, are also culpable in beer skunking. 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 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.
    In a sense, the aroma of light-struck beer doesn’t just resemble skunk spray, it is skunk spray! It’s the same stuff!

    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.

    Blue light, and to a lesser extent green are the most damaging to beer. Most wavelenghts of ultraviolet light are not a concern because glass blocks them quite effectively (that’s why you don’t get sunburned in your car). That is the reason beer in green, blue, and clear bottles is almost always skunked. Yes, even some very expensive imports.

    This also appears in a similar form in one of my home brewing books.
    posted by Gungho at 6:01 AM on January 29, 2006

    I guess Bud's really onto something with those stupid metallic bottles.
    posted by rxrfrx at 6:04 AM on January 29, 2006

    Finally, I can sleep at night.
    posted by Redruin at 7:11 AM on January 29, 2006

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