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Help with off flavors. Can you describe "oxidation"

I have a question about oxidation: what does it taste like? I’ve read that it gives off the flavor of wet cardboard but not sure if this fits the issue i’m having. Well, i’ve brewed a few beers and have had what I consider to be an off flavor with them. Seems like the brew starts off with good flavor but ends on a long, somewhat bitter (not hops), aftertaste. Thoughts?


Just like any off-flavor, you might really just need to have someone else with experience taste a beer that is obviously flawed, and point it out to you, to help you learn what it tastes like. That’s partially how I learned. Taste descriptors are not exact, but they’re in the right ballpark. So, oxidation might not taste exactly like wet cardboard… however, I do agreee that it is very similar to that.

I don’t get bitterness from oxidation. Quite the opposite, actually. To me, my 4-5 year old oxidized beers (yeah I keep some on hand) taste very much like caramel and maple, with, yeah, a sort of wet cardboardy flavor as well. The caramel and maple is due to the hops falling out completely with age – hops don’t last long like malt flavors do. But the cardboardiness… that’s the oxidation. Age some beers for yourself and find out.

The best thing you can try… purposely age any regular strength homebrewed beer for 3 years. Then, if you can remember how it tasted young and compare to how it tastes with age, you’ll see what’s happened. I’ve done this dozens of times. Not every beer will oxidize, but most will. If they contain a ton of alcohol, it seems to happen about 50% of the time. With lower strength beers, it happens more like 90% of the time. Do this to a whole bunch of different homebrews. Then taste them all side by side. The weird flavor that you detect in common with all very old beers is oxidation. Notice I said to do this with homebrews. Commercial brews tend not to oxidize anywhere near as quickly as homebrews. Some commercial beers will oxidize in a year. Others… it might take friggin 10 years. I have some 5 year old commercial beers that still have no oxidation, and I’m sure this is because they work really hard to eliminate any oxygen in their bottling process.

Okay… so, back to the OP. You might be experiencing astringency, which many people perceive as bitterness. Astringency is different from bitterness in that it is actually a feeling you get in your mouth, as opposed to an actual taste detected by your taste buds or nasal passages. Astringency has a tendency of drying out your mouth, as if you had filled your mouth with cotton, or chewed on a grape skin for way too long. Try this with grapes sometime… start to chew up a couple of grapes like you normally would, but then just suck all the juice out of them and save the skins (in your mouth), then chew and chew and chew on those grape skins, and notice what happens… that’s astringency. Like your mouth is full of cotton. Is that what you’re getting out of your beer??

If not… I might really just need to taste the beer myself to know what’s going on. Could be too much brewing salts, could be too much bittering hops, could be a couple dozen other things.

Oxidation initially tastes like a piece of wet cardboard or newspaper smells. However, oxidizing beer (or wine) can lead to a host of other problems and compounds to rear their ugly heads.

If it’s a pithy, unpleasant bitterness (like the rind of an orange), it may be a hopping issue, or perhaps even a water issue, but I would look over your process for points where oxygen may be getting introduced on the cold side as well.

It could also be the famed ‘extract twang’ from using slightly old/stale extract.

Sorry I couldn’t be of more help, do you have any BJCP’s or brewing clubs in your area? Much easier to diagnose if it can be tasted…

Thanks so much for the perspective on where to go with this. I contacted our local brew shop about it. I’m taking a bottle down there today to have them help with diagnosis.

Thanks so much!

post what you come up with if you dont mind. being a new brewer, im interested in what you come up with, since im sure ill experience it at some point

In low amounts, it tastes more like sweetness than it does like cardboard. I think a beer has to be pretty severely oxidized before you taste cardboard.

Local brew shop gave the brew in question a taste. Actually said my APA was good. No oxidation. the flavor i’m getting is a slight metallic finish. They think it is due to the water I’m using.

I agree. Advanced oxidation leads to cardboard and honey flavors, but early on it can taste sweet. To me, it can taste like honey or resemble the effect of using too much Crystal Malt.

[quote=“Misfit”]Local brew shop gave the brew in question a taste. Actually said my APA was good. No oxidation. the flavor i’m getting is a slight metallic finish. They think it is due to the water I’m using.[/quote]IT also could be the dreaded “extract twang” that Pietro mentioned. To me that can taste metallic late in the palate.

I agree that it could possible be “the twang” if you used a lot of malt extract. “Twang” to me tastes sort of like caramel, banana, and wet cardboard all rolled into one. This can be minimized by switching to partial mash, by using 100% distilled water, and/or by following a whole bunch of other steps that I have outlined here:

D+++m Dave! I need a Jeweler’s monacle to read that, and I’d really like to read it. I know, it’s my age!

If you click on it it it gets a little better. Then if you save it to your pics folder, you can zoom in on it there.

Thanks Dsiets. That helped a lot. I’m also computer illiterate.

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