Help differentiating oxidation & astringency

[dustinstriplin]

I could use some help determining the difference between oxidation and astringency. I've heard oxidation may have a wet cardboard flavor. Does oxidation also produce a drying effect on the tongue? I always thought it did, but I'm not sure now. When watching the sensory talk during homebrewcon, the speaker said a great example of astringency can be produced by sucking on your tongue to dry it out. If oxidation produces a drying sensation, what do you recommend to differentiate astringency from oxidation?

 

[day_trippr]

I do not feel the character defects incurred through oxidation would be in any way confused with classic astringency induced by excessive tannins extracted from the mash (typically by a defective sparge, using too high pH liquor) or by excessive polyphenols from cold-side hopping with certain strains (a favorite "whipping boy" around here in that regard is Galaxy ).

Oxidation attenuates almost every good character in beer to the point they can literally disappear entirely. First the aroma attenuates to zero, then the flavor does the same, leaving a sickly sweet but otherwise flavorless end that usually has suffered visually as well (greatly darkened). And note - this is all WAY BEFORE THE CARDBOARD AND SHERRY FINALE!

Cheers!

 

[dustinstriplin]

Thanks, that helps a lot in aligning the way I think about these flaws.

 

[palmtrees]

Yeah, I agree with day_trippr, the flavors are quite different. Astringency will feel dry and sometimes bitter. I've accidentally mashed super high before and got a ton of tannins in a beer, and it tasted like eating a black tea bag. It had a weird bitterness up front, different from hop bitterness but it definitely read as bitter. Oxidation, on the other hand, I perceive as reducing bitterness and giving the beer a sickly sweet flavor in place of the hops/malt character.

 

[Bassman2003]

I have been learning a lot about oxidation over the past few years and it is always there in varying degrees. Imperceptible in the beginning stages moving on to replacing real flavor with hyped up sweet & candy/sherry like flavors. It takes a lot of effort to keep oxidation at bay.

 

[Birrofilo]

Astringency is the flavour you get when you over-infuse black tea, basically this is the basic flavour of tea in the canteen of the Hall of Residence when I was at a British University and they had this habit of putting the tea bags in the great cylinder and leaving it there forever. (At least in Britain, there should be a law against this). It can be good with rye crackers and butter, disastrous with anything else. So, steep a tea bag for 10 minutes in boiling water, taste, that is astringency.

Oxidation is also easy to learn: open a bottle of beer, leave it in the open for one day, sipping a bit every few hours, and "enjoying" increasing degrees of oxidized beer. Oxidation begins as a "dullness" which takes away aroma, even if not immediately perceived as "oxidation flavour".