Barley Mowat 

The Science of Spoiling Beer

with 25 comments

In a previous article, I lamented the fact that craft beer contains alcohol. Lots of alcohol. So much alcohol, in fact, that it makes drinking a single bomber of most craft beer something you probably shouldn’t be doing on a weeknight.

This presents a problem for me, though, as I LIKE drinking beer on weeknights. I mean, I really, really like it. My day job is very stressful, you see, and I needs me medicine.

Fine, I’m a hammock field tester.
I’m just not very good with stress, okay!?

So what to do? Do I crack a bomber, drink half, and pour the rest out? Do I wake up very early the next day to finish it before it goes off? Maybe I put a cork in it and hope for the best?

That last one intrigued me. I had always just assumed opened beer would be bad by the next day, or at least degraded to the point you wouldn’t want to drink it. But really, is this the case? Time for good, old fashioned science to play its part and let us know. I crafted a quick experiment, and here are the results.


Properly corking a beer will result in a still-enjoyable product 24 hours after originally opening it.


Not wanting to run this experiment with bombers of vintage Singularity, I purchased two six packs of craft beer to use: one hop forward and one more malty. The hop-forward beer (Lighthouse Switchback) should demonstrate deterioration of hop aromatics, while the maltier pack (Parallel 49 Gypsy Tears) should age more gracefully.

From each six pack I cracked three bottles, poured out half, and capped one of each with a cork, a silicon “beer saver” cap, and nothing. After 24 hours I tasted each of the three old beers blind, alongside a freshly-opened bottle.

In this case, “Poured out half” means “Drank.” SCIENCE!


This should be easy, right? The fresh beer should stand out, the uncapped old beer should be awful, and the cork should slightly edge the silicon cap (if only because these don’t have a great seal and are prone to popping off).

Well, dangit, it was much harder than really it should have been. I’m pretty sensitive to oxidation (the primary fault that would creep in here), and for the most part these beers did not have a significant O2 level in them. Here are the results (left column is what each bottle was, and the right two are what I thought they were, grouped by beer, with qualitative comments).

Normal people have fridges like this, right? This is a perfectly normal thing, yes? Why is no one saying anything?

Cap Method (Reality) Switchback (Chuck says) Gypsy Tears (Chuck says)
Fresh Cork (V Good) Fresh (V Good)
Cork Cap (Good) Nothing (Bad, see below)
Cap Fresh (V Good) Cork (Good)
Nothing Nothing (Ugh) Cap (Not great)


Some of these were closer together than others, but in general the best two beers were hard to tell apart. The hoppy beer, which should have suffered grievously at 24 hours of oxidation, was not bad at all, and actually was brilliant both in fresh and corked form.

The take-away? Cork your beers and drink them tomorrow. They’ll be fine–better than you’d think. If you don’t have a cork, those little silicon caps are okay, but they do tend to pop off so watch out for that (if they don’t pop off, they perform as well as, if not slightly better than, corks).

Leaving the bottle open, though, will ruin your beer. So, yeah, definitely don’t do that. Big shocker there.


  • I suspect the cork on the Gypsy Tears might have failed, due to P49’s use of a tighter neck than normal bottles. I’d redo the experiment, but I’m lazy.
  • The capped Switchback was great. Indistinguishable from fresh. Cork wasn’t much worse.
  • The capped Gypsy was easily differentiated from Fresh, but not a massive degradation in quality overall. It wasn’t unpleasant, just different.
  • I theorize that when left standing still, a layer of heavier CO2 will form and displace the lighter O2 from contact with the fluid. In an uncapped bottle, though, the CO2 would eventually just escape, leaving behind a flat beer directly mixing with that loutish bastard oxygen.
  • I also theorize that the high hops of the Switchback actually masked the oxidation that was apparent in the Gypsy Tears, rather than suffering an even stepper decline like I had originally thought. You learn something new every day.

Written by chuck

March 18th, 2014 at 3:30 pm

Posted in Beer and You

25 Responses to 'The Science of Spoiling Beer'

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  1. I would like to think it was my comment on the high ABV post that got you doing this… 😉

    Curious if there would be any difference in pouring out the remainder into a smaller bottle (only when original is larger bottle to start with) – theory being that the smaller bottle has less air space and thus less oxygen. The issue would be does the pour itself into the smaller bottle cause as much damage.

    Thoughts? Test part 2?


    18 Mar 14 at 16:20

  2. I’ve got one of these wine vaccuum sealer thingies on the assumption that removing oxygen from the bottle was smart. I’m still on the fence, but I suspect it also pulls a significant amount of CO2 out of solution overnight and leaves a flatter beer for the next day.

    Maybe I should throw science at this one too.

    Dave S.

    18 Mar 14 at 17:24

  3. I’m more curious about carbonation. As similar as a beer might taste 24 hours later, it won’t be as good if flat.

    Although, I suppose RIS and Barleywines might still be quite drinkable without that carbonation.


    18 Mar 14 at 17:24

  4. I have used wine sealers with varying degrees of success. If a beer is highly carbonated I have found that it actually foams the beer up in the bottle and results in a more flat beer the following day.

    I have switched to using a cork cap (like found on port bottles) and find that while there is slightly less carbonation the next day it isn’t a huge difference. As noted by Pbeau, lower carbonated beers seem to hold up the best.

    I wonder if a inert gas ( would provide the best results. They use something similar on growlers and I find I can go 2 days with no noticeable difference in taste or carbonation.


    18 Mar 14 at 17:53

  5. Cool experiment. You should take it one step further and see how long can pass before a significantly noticeable degradation occurs for each of the capping options

    Simon Droscher

    18 Mar 14 at 18:30

  6. I’m with you in lamenting the EtOH content of many good craft beers. Its even lead me to supplanting Red Racer IPA with Red Racer ESB as my go-to, have-no-time-to-look-around beer because of its lower ABV.

    Anyways, I’ve had great success just using those simple wine bottle stoppers (the ones that have a flip down function that fattens out the bottle-sealing rubber thing-a-majigger). Granted I only rarely stretch a bomber out past 2 days but recently did with a precious bottle of Bird of Prey and was quite pleased with the quality on day 3. So yes, definitely a viable option!

    Alex B

    18 Mar 14 at 22:33

  7. i’m so happy i’m not the only one with this problem…as a singleton i stare at my selection longingly during the weekdays knowing that i shouldn’t crack one open for fear of a) waste-age or b) hammer-age.
    i’ve considered pouring the leftover into a capped bottle a la Howe Sound Brewing but it just seemed wrong. had not thought of corking…although carbonation is probably going to be an issue and that would peeve me to no end.
    even mini growlers are problematic the next day.
    my only solution has been to stick with single servings during the week. problem solved? not really.


    19 Mar 14 at 08:34

  8. @Damon – I’d think the act of pouring the beer would mix it pretty decently with O2. Of course, pouring it out in the first place accomplishes much the same… this is indeed worthy of another experiment, but I’ve had my fill of slightly off beer… for now.

    @Dave – Yup, that’s exactly what I’d expect you to get. That’s why I didn’t even try to use Sharon’s for this experiment. I figured carbonation trumps oxidation.

    @Pbeau – Neither of these beers was of a particularly highly carbonated style. The Switchback was the highest carb, but the difference 24h later was not noticeable, at least for the bottles that had something on them. The uncapped bottle retained some carb, but was pretty dreadful.

    Inert gas (usually Argon) would provide quite a decent result, as it displaces any and all O2 out of the bottle. However, it’s quite pricey to boot. You might be able to rig one of those to use straight CO2 and turn your bottle into a mini keg, but again that’s a chunk time and money.

    @Simon – Um… how about you do that one, okay? 🙂


    19 Mar 14 at 08:59

  9. With regards to the high hop content in the Switchback masking oxidization, wasn’t that the tale of how IPA’s came to be, loading up on the hops so it would not spoil on the voyage to India? Or is that an old wives tale?

    @AlexB, I’ve started to do the same; my preferred go-to is Phillips Bottle Rocket ISA.


    19 Mar 14 at 10:39

  10. @Nick – Hops are a preservative, so the thought was that the high hops would keep out bacteria a bit more successfully than low hop, low-abv beers. That’s a bit different than oxidation.


    19 Mar 14 at 10:43

  11. I located a simple, cool little device called a Hermetus Bottle Opener & Resealer. They were selling them at Restoration Hardware a while ago.

    Nice minimal German design. It has a tapered top that lets you really squeeze it onto any (relatively normal) sized bottle top and it seals well enough that you get a very respectable pop/hiss sound when you open after a day or two.

    I usually do just one day but have tried up to 2, and as with your results I find the results to be totally acceptable with all beers I’ve tried so far.

    Scott Cameron

    19 Mar 14 at 12:06

  12. Thanks Scott, I forgot totally about the 2 Hermetus my parents had when I was a kid. We used them mainly for apple juice bottles though, I didn’t find them very handy.
    My grandfather in Germany used something like this on his beer bottles: I also forgot about that until I stumbled across a bunch of them last summer at European Specialty Food importers on Union St. Bought 4 at 25 cents each. I didn’t see them again at subsequent visits. Actually I even used 2 of them for bottling home brewed apple cider when I ran out of flip-top bottles, I haven’t checked the resulting carbonation yet – maybe I will this weekend.


    20 Mar 14 at 14:58

  13. I would be also curious about results for pouring the remains into a smaller bottle. This would be also interesting for growlers, if you can get only 1 liter or 1.9 liters.
    Does anybody has experience how a half full or 1/4 full growler does? Especially the latter one contains a fair amount of air/oxygen.


    20 Mar 14 at 15:05

  14. (Frank_Z) I’ve let beer sit in a half full growler and a quarter full. Honestly, after opening a growler I find the next day the carbonation is a little less, however the beer is still pretty good (in some cases better if it is an ageable beer). Quarter or less though or more than one day and it’s no good. I find half growlers the next day are ok too, you just need a good seal on the cap.

    In fact, if I have a growler of something that I think is a little off balance, I will often only have one that night and save the rest for the next night.


    21 Mar 14 at 07:58

  15. I’ve found growlers don’t bode too well on the carbonation front once open. There is also a sense of lack of freshness but that’s probably mostly in my head. The taste remains but the original intent of the beer is lost.


    21 Mar 14 at 09:07

  16. When I only want to drink half of a bomber, I seal it back up with these plastic caps with hooks on the side that are used to reseal champagne bottles. I’ve always called them ‘bouchons” but that might be a misnomer. Seems to do a fine job and you don’t have to worry about them popping off if the bottle gets jostled. Interesting to read your results!


    21 Mar 14 at 09:39

  17. I have found that most British style ales (micro brews) are just fine the next morning (half empties…) without capping or corking. Still have carbonation, they’re just warm…but british ales are OK at room temp IMHO.

    Ted Kritzler

    21 Mar 14 at 13:15

  18. Great read! I personally use a levered wine stopper. The kind where you insert it and pull down the lever which causes a silicone band to expand in the neck. Works great and I have left beers for up to three days and they still had great carbonation and little change in flavor. I may try to leave one for a week or so to see what happens. I would assume it would oxidize. I’ve always stored them in my keezer or fridge when corked so another test would be to see what would happen if they were left at room temperature while corked.


    22 Mar 14 at 20:01

  19. My (not scientific) method finds that wine pumps make beer flat, silicon “beer savers” work well for a day or two but pop off during transit (co2 buildup?), pouring from large to small doesn’t work (same oxygenation principle that does work on some wines). Love the Grolsch/Howe Sound clamps but reseal immed even if I’m gonna have a 2nd glass just after. My dilemma (on a school night 😉 is whether to open the 2nd bomber…btw I always cook with flat beer.


    23 Mar 14 at 14:42

  20. Dave, what’ s a keezer ?


    23 Mar 14 at 14:54

  21. The levered wine stopper and champagne bottle re-sealer sound interesting. The one I talked about above with the link doesn’t seem to hold carbonation very well, at least not for a longer period of time.


    23 Mar 14 at 20:22

  22. Gird, a keezer is a keg freezer. Basically a kegerator but made with a chest freezer instead of a fridge. I keep three kegs of homebrew on tap in my kitchen.


    26 Mar 14 at 17:29

  23. Here’s a link to the type I have had success with.


    26 Mar 14 at 17:39

  24. The bottle stopper posted by Dave is exactly the one I use and works like a charm. Just tested and my Red Racer IPA bomber still tasty (and carbonated) on Day4! I pour what I want and quickly pop the stopper in.

    Alex B

    26 Mar 14 at 19:12

  25. No Work Tomorrow Beer Opener

    […] the CO2 would eventually just escape, leaving behind a flat beer directly mixin […]

    Frame Blog

    9 Jul 17 at 16:10

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