Oxidization?

[smok3y666]

I have 2 barrels, one a Wilko's special, the other a KK. The Wilko's one developed a leak again around the rubber seal on the tap so I tipped the barrel up slowly, removed the and replaced the rubber seal and regassed. The leak carried on so I swapped the lid for a spare and the leak stopped so I regassed and added a little sugar as it is in the 3rd day of secondary. The KK had a replacement tap fitted before I transferred the beer into it which started to leak from the actual tap quite a lot on the 2nd day of secondary. So I refitted the original tap and regassed and added alittle sugar. What are the chances of the beers getting oxidized? I didn't swill the beer up and reprimed slightly, and added co2. Or is if just fingers crossed?

[PMH0810]

MoM (My old Man) visited Saturday and tried my JB Chocolate Stout. His Mrs said it tasted like iron (it doesn't - she's a wine drinker anyway) and this sparked MoM on about oxidisation.

I think it's fine; SWMBO thinks it's fine and some drinking buddies of mine really rate the brew.

What are the symptoms of oxidisation? Just so I can shout him down?

[Jim]

MoM (My old Man) visited Saturday and tried my JB Chocolate Stout. His Mrs said it tasted like iron (it doesn't - she's a wine drinker anyway) and this sparked MoM on about oxidisation.

I think it's fine; SWMBO thinks it's fine and some drinking buddies of mine really rate the brew.

What are the symptoms of oxidisation? Just so I can shout him down?

Wet cardboard is the classic smell and flavour.

[PMH0810]

Thank you Jim - you've just helped me shoot MoM and his missus down in flames. JB Choccy Stout has a nose(?) strong in choccy and hops and definitely no hint of wet cardboard (or wet dog!).

[Aleman]

There are other signs . . . generally a fading of the hop and malt presence is the classic, exhibits as a dullness of the flavours on the palate. Sherry is the classic post fermentation oxidation flavour, you might (in a delicate beer) get some green apple notes . . . but in a robust stout you are very unlikely to get any of these unless you age for a long (long) time as dark beers are high in antioxidants.

Wet cardboard is a sign of a completely different form of oxidation and you are practically never, ever going to ever experience it

[Jim]

.......Wet cardboard is a sign of a completely different form of oxidation and you are practically never, ever going to ever experience it

Could you expand on that, Aleman?

[MartialAnt]

Wow my first 3 brew i made i stirred them during fermentation and they are all fine. I swear down i read somewhere (not on this site) that for the first 3 days of fermentation you should stir it. Well the 3rd brew stopped fermenting after a few days so i gave it stacks to make it bubble up. Wish i could find where read it.

1st lot was drunk just as it had conditioned. 2nd is a bit flat but the saaz hops helped give it flavour in the end & the 3rd which is now in the cold is gonna be another fine drink. Had a few just to make sure.

Obviously not going to stir it again now ive found out what is likely to happen.

Maybe im just a lucky sod.

[Aleman]

.......Wet cardboard is a sign of a completely different form of oxidation and you are practically never, ever going to ever experience it

Could you expand on that, Aleman?

Ad nauseam

Wet cardboard is the classic description of the compound trans-2-nonenal (T2N) which is the end result of aldol condensation of short chain aldehydes. T2N has a taste threshold in the region of 0.1 ppb (Yes parts per billion ). The major cause of the production of T2N is via enzymatic pathways involving lipase and lipoxygenase . . . but96% of these enzymes are lost on malting . . . American 6 row malts have higher levels of these enzymes than British two row malts. There is a non enzymatic pathway for the production of 2TN which unfortunately brings us on to the discussion of 'hot side aeration' it is believed that oxidation occurs in the mash increasing the T2N potential of the beer . . . if brewed with a malt already high in lipase/lipoxygenase then there is the potential for T2N levels to rise above the taste threshold in the final packaged beer. . . . again this may only be noticeable in extremely pale beers, as darker beers have a higher level of antioxidants . . . and higher kilned malts have less T2N potential (less lipase/lipoxygenase) than paler kilned malts.

Given that it is only very pale 6 row malts that are likely to have problem levels of T2N precursors it is very very unlikely that anyone in the UK is going to detect T2N in their beer.

[Jim]

.......Wet cardboard is a sign of a completely different form of oxidation and you are practically never, ever going to ever experience it

Could you expand on that, Aleman?

Ad nauseam

Wet cardboard is the classic description of the compound trans-2-nonenal (T2N) which is the end result of aldol condensation of short chain aldehydes. T2N has a taste threshold in the region of 0.1 ppb (Yes parts per billion ). The major cause of the production of T2N is via enzymatic pathways involving lipase and lipoxygenase . . . but96% of these enzymes are lost on malting . . . American 6 row malts have higher levels of these enzymes than British two row malts. There is a non enzymatic pathway for the production of 2TN which unfortunately brings us on to the discussion of 'hot side aeration' it is believed that oxidation occurs in the mash increasing the T2N potential of the beer . . . if brewed with a malt already high in lipase/lipoxygenase then there is the potential for T2N levels to rise above the taste threshold in the final packaged beer. . . . again this may only be noticeable in extremely pale beers, as darker beers have a higher level of antioxidants . . . and higher kilned malts have less T2N potential (less lipase/lipoxygenase) than paler kilned malts.

Given that it is only very pale 6 row malts that are likely to have problem levels of T2N precursors it is very very unlikely that anyone in the UK is going to detect T2N in their beer.

Thanks, Aleman. So in other words, the wet cardboard taste would come from the fabled hot side aeration - oxidation in the finished beer gives the taste you described in your earlier post?

Learning all the time!

[Aleman]

Thanks, Aleman. So in other words, the wet cardboard taste would come from the fabled hot side aeration - oxidation in the finished beer gives the taste you described in your earlier post?

Learning all the time!

I know, you are sorry you asked now

fabled HSA is not the only source of T2N, badly produced malt is also another possible source

Cold side oxidation will lead to the effects I described earlier, particularly post fermentation oxidation.

[fivetide]

When Aleman gets technical my brain really does hear him as Alec Guinness playing Obi Wan...

"I felt a great disturbance in the brew, as if millions of yeasties suddenly cried out in terror and were suddenly silenced. I fear something terrible has happened."

[Aleman]

I need a new avatar