Oxidised Brew

Sorry to start this whole mash/boil oxidation/HSA debate all over again but I've had a problem with a few of my all grain beers and I haven't quite been able to pin it down - until now. It's been in primary for 2 weeks and as I was taking a taste test last night prior to kegging I made my discovery. This time the flavour is stronger and it has that 'sherry' taste so I can only presume it's oxidised.

This is my process if anyone can spot any obvious flaws:

* Fill cooler mashtun with strike water, add grains and mix thoroughly
* Mash for 1 hour
* Add infusion water to compensate for grain absorption. This was added from the Hot Liquor Tank (Burco-type boiler) through a syphon hose which i ran onto an upturned plastic plate on top of the grain bed to minimise splashing. (maybe i should just place the end of the syphon under the surface of the water?)
* Recirculate into 2 litre jug and pour gently over grain bed (again on top of plate). Repeat
* Stir grain and open tap to run off into boiler through syphon hose
* Add sparge water using the same method as above, rest, stir, recirculate and run off using the same methods as above.

Is it possible that it's picking up oxygen in the syphon hose? I start off by opening the tap slowly and after recirculating I gradually turn it until it's open fully.

When adding hops during the boil I stir the wort with a plastic spoon.

One other thing I should mention is that the previous brew is showing signs of oxidation, although not as bad - I roused the yeast with that brew so maybe I introduced oxygen during fermentation - is it possible that oxidation flavours would carry over through yeast slurry??

I didn't see anything about temps.

if you mash really low (like my first attempt) you can get that off flavor.

Did you final gravity come out low?

bigears said:

- is it possible that oxidation flavours would carry over through yeast slurry??

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Possible yes, but I suspect your wort handling methods post boil.
Going with my own experience, I have aerated my mash on occasion
unintentionally. Never got any off flavors from it yet.
When I mishandled my brew post ferm, I got oxygenation issues.

To get an oxidized brew from the mash would require you to almost intentionally try to oxidize it. You would have to open your tap on the mash tun and let the wort free fall a couple of feet into your kettle or bucket so it really splashes and foams up. You are using a hose on that spigot aren't you?

One thing about your procedure that I do question is about your recirculation. You say you stir after you recirculate. That defeats the purpose of the recirculation. The recirculation, or more properly "vorlauf", it to set your grain bed so you get clear runoff. By stirring after vorlauf, you are breaking up the grain bed, this will then allow grain particles get into your wort. What you are calling oxidation, is more likely tannins extracted when you boil those pieces of husk. Actual oxidation will give your beer a taste like wet cardboard and will generally take months to show up.

Oxidation will give very malty high alcohol beers like barleywines a sherry like taste, but that involves very low amounts of oxygen from normal leakage through bottle cap seals and takes a year or two to manifest itself. The fact that you are noticing this after only two weeks in primary leads me to believe it is something else entirely.

I have done some serious, but unintentional splashing of my wort preboil and have yet to come up with any signs of oxidation in those beers.

Wayne
Bugeater Brewing Company

Thanks for the replies guys, there are a few things there for me to focus on, and I'll see if they make a difference.

if you mash really low (like my first attempt) you can get that off flavor.
Did you final gravity come out low?

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* I mashed around 64C (147F)and it dropped around 1C over the course of an hour. Final gravity was 1.010 from 1.042 which I thought would have been in range (WLP002 yeast). Maybe I'll try mashing a little higher this time.

One thing about your procedure that I do question is about your recirculation. You say you stir after you recirculate. That defeats the purpose of the recirculation. The recirculation, or more properly "vorlauf", it to set your grain bed so you get clear runoff. By stirring after vorlauf, you are breaking up the grain bed, this will then allow grain particles get into your wort. What you are calling oxidation, is more likely tannins extracted when you boil those pieces of husk. Actual oxidation will give your beer a taste like wet cardboard and will generally take months to show up.

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* Avoid stirring after vorlauf (now that I think about this I'm not sure if I even do this, I typed up that procedure off the top of my head Either way it's a good point so I'll avoid doing this)

Possible yes, but I suspect your wort handling methods post boil.
Going with my own experience, I have aerated my mash on occasion
unintentionally. Never got any off flavors from it yet.
When I mishandled my brew post ferm, I got oxygenation issues.

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* Be more careful about post boil handling - I wonder if shaking the fermenter or rousing the yeast was causing problems. In any case, from checking the gravity afterwards I don't think it was neccesary so I'll try to avoid this in future.

maybe you meant to say that you stir the mash after each addition of sparge water (that is if you are batch sparging and are not fly sparging).

Hi delboy (good to know we frequent the same forums )

Yes, I do batch sparge. I should have said that I stir thoroughly after each addition of water.

I add the water, stir, let it rest, stir again and then vorlauf and drain. It's the Denny Conn batch sparge technique which I know most of you are familiar with. Now that I've thought about it I'm sure I haven't stirred after vorlauf.

Beer doesn't taste right, just out of fermentation. It does need to age a bit, like 3 weeks in the bottle/keg.

Isn't 'oxidised' the taste of wet cardboard? And, doesn't it take long time to go stale in the bottle?

Has anybody else sampled your aged brew? What do others say about the taste?

Two weeks total, brew to keg, no secondary, seems a bit hasty. Have you heard of the 1-2-3 rule? One week in primary, two weeks in secondary, three weeks in keg, before drinking.

What kind of yeast are you using? I wonder if you're just getting some unusual sherry like flavors from your yeast? I've never experienced HSA and I don't know anyone who has so I think it's probably something else. Maybe oxidation later in the process? Maybe stressed yeast? Some very high alcohol beers have a sherry-like flavor- are you making high ABV beer? If that's the case, the flavor will mellow some.

I'd say try again, using a dry neutral yeast like nottingham. If the oxidized flavor is gone, you know it was related to the yeast.

Isn't 'oxidised' the taste of wet cardboard? And, doesn't it take long time to go stale in the bottle?

Has anybody else sampled your aged brew? What do others say about the taste?

Two weeks total, brew to keg, no secondary, seems a bit hasty. Have you heard of the 1-2-3 rule? One week in primary, two weeks in secondary, three weeks in keg, before drinking.

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I don't want to open up the debate about the merits of secondary because I know there's been a lot about this recently. By and large I now do a longer primary and rack to the cornie and let it age there. I don't end up drinking it any sooner but it doesn't have the intermediate step.

Sherry-like flavour is also an indication of oxidation but maybe I'm not diagnosing the flavour correctly - as you say I should get someone else to taste it too.

Maybe stressed yeast? Some very high alcohol beers have a sherry-like flavor- are you making high ABV beer? If that's the case, the flavor will mellow some.

I'd say try again, using a dry neutral yeast like nottingham. If the oxidized flavor is gone, you know it was related to the yeast.

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I'm using WLP002 (English Ale). The flavour early in fermentation was exactly what I would expect from this yeast but it's changed as fermentation has progressed. It's a session bitter about 1.045 so I don't think this taste is true to style (if it was a barley wine maybe it wouldn't concern me). I've made this again last night, more or less the same recipe but using US05, we'll see how this one works out

Thanks all for your suggestions!