infection or oxidation??

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DarrenSL

DarrenSL

Well-Known Member
Joined
Apr 25, 2015
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Location
Manchester
I have had a long standing and persistent off flavour that I just can't seem to evade. I am well read in homebrewing and my technique is good. But I still get this flavour/aroma in approx 50% of the brews I make. I could really do with some opinions on this on what to try next!!

OK...

My experience is not bad. I'm well read (especially from HBF UK :)) with 2 years AG brewing, c. 50 brews across a wide variety of styles. Surprisingly, I've never had this off flavour in any decoction mash (lager, wheat beer) but that could be just a fluke.

My equipment is good. Stainless steel FV, new silicone tubing.

my sanitation is obsessive. Soak in Precarbonate/oxiclean or hot drain cleaner (caustic). All removable items (taps, tubing, etc) is steam sterilized for half an hour. I sanitise with Peracetic acid or starsan.

my process is cautious. I put a net over the wort when cooling (to keep flies and dust out). My cooling is pretty quick (immersion chiller c.15mins) and all transfers are done covered in cling film to keep house dust out. Oxygenation is done through oxygen cylinder and scintillated steel (boil santized).

Fermentation temperature is controlled.



The off flavour is best described as old vegetables. It starts off distracting (particularly because I can now spot this flavour a mile off!) but over 2-4 weeks deteriorates further to the point that I'd rather pour it down the drain. It is usually accompanied by a turbid/cloudy appearance and, also worthy of mention, my fermentations tend to over-attenuate (80-90% typically).

More recently, I noticed that beer, when young, had a very distinctive sherry flavour/smell! This has got me thinking (and hoping!) ... oxidation! I drain my wort into plastic buckets. They then get poured at c.60C (with inevitable splashing) into the kettle.

I have also been guilty of pitching yeast at too high a temperature (paranoid about infection and trying to get the yeast in asap). I noticed that my last couple of brews went into the fermentation chamber at around 26C so was probably 27-28C when I aerated!


Apologies for the long post, I want to get all the facts and am in a desperate position. This is holding back my brewing ffs!

Does this sound like oxidation or infection? Any thoughts/ideas where I can go next? Is there a nuclear sanitation option I could try? Anyone got any spare cobalt-60? :grin:
 
think you nailed it with the second from last paragraph. when you pitched at this temp did you let the temp drop naturally soon after pitching and maintain a recommend temp for Ur yeast?
I think as long as you've cleaned and sanitized well a lower temp won't do harm when pitching.
 
Thanks for the rapid response :)

Yes, the FV was put in the brew fridge and cooled over 12 hours down to 19C.

I really do hope it is oxidation, at least I have control over that and can do something about it. I just don't know if I'm clutching at straws in desperation. The logical part of me says that surely there are loads of people splashing hot wort around and throwing their yeast in at a little above the recommended temperature. I just don't seem to come across many people commenting on rotting veg smells.
 
anything in this make a ding?

https://www.cicerone.org/sites/default/files/resources/off_flavor.pdf

Maybe boiling with the lid on?
Dimethyl Sulfide (DMS)

Tastes/Smells Like:
Cooked vegetables, especially creamed corn, cabbage, tomato, shellfish/oyster-like flavours

Possible Causes:
S-methyl methionine (SMM) is created during the malting process of grain and is later
converted to DMS when heated. Darker base grains have less DMS as the kilning process converts SMM to DMS and drives it off before going into the wort. This makes DMS naturally more prevalent in pale ales
and lagers.

How to Avoid:
When boiling wort, DMS is driven off through evaporation. It is very important to always
maintain a strong rolling boil for at least one hour. Some brewers boil for 90 minutes to ensure that as much DMS is driven off as possible. Avoid letting condensation drip back into the wort and never cover your kettle completely during the boil. Long cooling times can also lead to excess amounts of DMS. Cool your wort to pitching temperature as quickly as possible with a wort chiller or ice bath. Finally, a strong fermentation with lots of Co2 production helps to clean up DMS since the bubbles carry DMS away, so pitching high quality yeast is a must.
Click to expand...

Don't see why the taste would get progressively worse though.
 
Thanks Rob. Yes, DMS was my first crusade (90 minute boils, lid off)! Followed by extreme sanitation (bake/boil/caustic/PAA acid). None of the common off flavours seem to apply. I wouldn't even say it was reminiscent of wet cardboard either.
 
DarrenSL said:
Thanks Rob. Yes, DMS was my first crusade (90 minute boils, lid off)! Followed by extreme sanitation (bake/boil/caustic/PAA acid). None of the common off flavours seem to apply. I wouldn't even say it was reminiscent of wet cardboard either.
Click to expand...

I suppose the only thing you can do is eliminate, as far as possible, any oxygen and see if it works.

http://byo.com/body/item/1196-oh-that-smell

6. Day-old (liquid) bread
Hints of cardboard, paper, sherry-like, and sometimes rotten vegetables typically indicate degrees of oxidation in your beer. Oxidation is accompanied by a reduction in the malt and hop flavor in your beer. The problem: Low levels of alde*hydes (one type of flavor chemical in beer) that once were reduced or fresh have oxidized.
If your beer is exhibiting early signs of staling, your yeast can to some degree reverse oxidized aldehydes. (Remember, yeast are great scavengers!) This may be your only defense once oxidation sets in. Once oxidation has progressed to the more pronounced sherry-like or vegetable-like flavors, there isn’t anything you can do to reverse it.
Avoidance tactics: Oxygen has many opportunities in the brewing process to stale your brew. Transfer your homebrew from vessel to vessel with the least amount of splashing possible. At bottling time minimize headspace in the bottle to three-quarters of an inch. Just prior to capping, some homebrewers even tap the sides of their bottles to release CO2 out of the beer and “push” oxygen out of the bottle, capping quickly thereafter. It is true that yeast will absorb some of the oxygen in the bottle but certainly not all of it, as they are no longer in their vigorous growth cycle. This often leaves plenty of oxygen left to cause staling reactions.
For all-grain brewers there is at least one more area to fight oxygen ingress. Although this is a subject of debate in some brewing circles, hot-side aeration could be staling your beer. Minimize splashing, frothing, or otherwise violently stirring your mash during the mashing and sparging process. While it is certainly beneficial to thoroughly mix your grains, try not to let the surface of the mash bed get disturbed.
Click to expand...
 
I would say yeast stress. Are you making starters? Starters can be a tad warm to get them up and running. Even rehydration is a good way to get the yeast awake and ready.
But, when you pitch, your wort should be in the middle of the recommended temp. Different strains have different temps but usually ale yeast are good around 22 degrees. I usually take it down to 19 or 20.
Another thing to look at is off flavors from the husks. Are you squeezing the bag or mashing too high? High temp sparging can do it as well. Your sparge water shouldn't be above 75.
 
DarrenSL said:
I have had a long standing and persistent off flavour that I just can't seem to evade. I am well read in homebrewing and my technique is good. But I still get this flavour/aroma in approx 50% of the brews I make. I could really do with some opinions on this on what to try next!!

OK...

My experience is not bad. I'm well read (especially from HBF UK :)) with 2 years AG brewing, c. 50 brews across a wide variety of styles. Surprisingly, I've never had this off flavour in any decoction mash (lager, wheat beer) but that could be just a fluke.

My equipment is good. Stainless steel FV, new silicone tubing.

my sanitation is obsessive. Soak in Precarbonate/oxiclean or hot drain cleaner (caustic). All removable items (taps, tubing, etc) is steam sterilized for half an hour. I sanitise with Peracetic acid or starsan.

my process is cautious. I put a net over the wort when cooling (to keep flies and dust out). My cooling is pretty quick (immersion chiller c.15mins) and all transfers are done covered in cling film to keep house dust out. Oxygenation is done through oxygen cylinder and scintillated steel (boil santized).

Fermentation temperature is controlled.



The off flavour is best described as old vegetables. It starts off distracting (particularly because I can now spot this flavour a mile off!) but over 2-4 weeks deteriorates further to the point that I'd rather pour it down the drain. It is usually accompanied by a turbid/cloudy appearance and, also worthy of mention, my fermentations tend to over-attenuate (80-90% typically).

More recently, I noticed that beer, when young, had a very distinctive sherry flavour/smell! This has got me thinking (and hoping!) ... oxidation! I drain my wort into plastic buckets. They then get poured at c.60C (with inevitable splashing) into the kettle.

I have also been guilty of pitching yeast at too high a temperature (paranoid about infection and trying to get the yeast in asap). I noticed that my last couple of brews went into the fermentation chamber at around 26C so was probably 27-28C when I aerated!


Apologies for the long post, I want to get all the facts and am in a desperate position. This is holding back my brewing ffs!

Does this sound like oxidation or infection? Any thoughts/ideas where I can go next? Is there a nuclear sanitation option I could try? Anyone got any spare cobalt-60? :grin:
Click to expand...

oxidisation is a problem AFTER fermentation has taken place. you should be splashing wort into the FV to aerate it prior to the start of fermentation.

If you think it's not DMS because of a long boil what about the hops being used, if left in too long they could give you those flavours/aromas?

Also re-hydrating the yeast means less chance of under pitching.

When I transfer from the FV to bottling bucket I use co2 to purge the bucket of air, thats worked well for me.

Hope you cure this issue because a good homebrew is a thing of wonder.

Your cleaning process sounds to be more than adequate. I'd say it was neither infection or oxidation. :hmm:
 
As it gets worse over time and your beer gets cloudy at the same time, my money would be on some sort of infection.
As to yeast pitching temperature - I regularly pitch at a highish temperature and never have any problems.
 
Well, since my last post on this thread I have brewed twice. A Schneider Weisse clone which was perfect and another hoppy pale ale (Mysterios SNPA from Malt Miller). Once again, I got the stale/veg flavour. I'm sensitive to it now so can detect it really early on. I knew this brew was wrong after 2 weeks in the fermenter. By week 4 it was ready for the drain.

So, after more research I stumbled on this and it seems I'm not the only one who is faced with this problem with hoppy beers!
http://www.homebrewtalk.com/showthread.php?t=378023

I'm 90% convinced that this is an oxidation issue. I don't get gushers, there is no sourness and my sanitation process is obsessive.

I'm curious to know if anyone else on his forum has this issue or if they don't how well do they protect their post boil wort from oxygenation.
 
It could well be oxidation, but I doubt it's happening hot-side. There's a lot of debate about HSA but it seems that the 6 row barley we use this side of the pond is not as susceptible as the US 2 row (this is also true of DMS so I don't think that's your problem either). As long as you have a good fermentation HSA shouldn't be an issue.
Presumably you take all the necessary precautions against aeration when racking/bottling/kegging etc?
 
Thanks Steve. I don't think it is HSA malt oxidation, I don't really get the wet cardboard aroma. It's just rotten stale beer I get. The beers I get this with all have hop content between 100-300g. I brew excellent lagers with the same equipment.

Now the only difference between the two is:
- I step mash my lagers
- There are a lot more hops in the IPAs

I do take all the usual precautions when racking/bottling/kegging, but my problem starts before that process. I can detect it in the fermenter.

The hops I use are always fresh (from vac packs) as well. I just wonder if heavily hopped wort needs to be handled more cautiously??
 
Maybe because you're oxygenating from a bottle your over doing it and oxidizing from the get-go ? I just think that a bottle will put massive amounts of pure oxygen straight in there (maybe more so than the yeast needs) where as the more traditional methods of oxygenating will only put a small amount in.
I'm not saying don't oxygenate from a bottle but maybe turn the pressure right down.
 
OK, follow up ... I brewed another SNPA and guess what ... rotten stale off flavour again. Great after 2 weeks, detectable after 3 and by 4 it'll be down the drain.

I tried to eliminate all possible issues this time.

- Brand new thermos mash tun - to maintain temperature and so I can mash out and get on the boil asap. One theory I had was it could be oxidation due to hot wort sitting around for too long
- Brand new tubing
- Brand new 3 piece SS tap, just in case my old one piece was hiding something
- Only 30secs of oxygen (to avoid over oxidation of hops).

The flavour is definitely originating in the fv. In fact the settled yeast reeks of it! (could be a clue?!?). I get this problem with liquid and packet yeasts!

By process of elimination, it can only be the fv. I did notice that the silicone ring seal on the fv also smelled of it so soaked it in bleach before the last brew but to no avail.

I have cleaned the fv with hot caustic, percarbonate/oxi clean and peracetic acid, again to no avail.

I have completely run out of ideas now! I think I need something radical. Does anyone have any ideas of what I can try next?

Thanks.
 
DarrenSL said:
I have had a long standing and persistent off flavour that I just can't seem to evade. I am well read in homebrewing and my technique is good. But I still get this flavour/aroma in approx 50% of the brews I make. I could really do with some opinions on this on what to try next!!

OK...

My experience is not bad. I'm well read (especially from HBF UK :)) with 2 years AG brewing, c. 50 brews across a wide variety of styles. Surprisingly, I've never had this off flavour in any decoction mash (lager, wheat beer) but that could be just a fluke.

My equipment is good. Stainless steel FV, new silicone tubing.

my sanitation is obsessive. Soak in Precarbonate/oxiclean or hot drain cleaner (caustic). All removable items (taps, tubing, etc) is steam sterilized for half an hour. I sanitise with Peracetic acid or starsan.

my process is cautious. I put a net over the wort when cooling (to keep flies and dust out). My cooling is pretty quick (immersion chiller c.15mins) and all transfers are done covered in cling film to keep house dust out. Oxygenation is done through oxygen cylinder and scintillated steel (boil santized).

Fermentation temperature is controlled.



The off flavour is best described as old vegetables. It starts off distracting (particularly because I can now spot this flavour a mile off!) but over 2-4 weeks deteriorates further to the point that I'd rather pour it down the drain. It is usually accompanied by a turbid/cloudy appearance and, also worthy of mention, my fermentations tend to over-attenuate (80-90% typically).

More recently, I noticed that beer, when young, had a very distinctive sherry flavour/smell! This has got me thinking (and hoping!) ... oxidation! I drain my wort into plastic buckets. They then get poured at c.60C (with inevitable splashing) into the kettle.

I have also been guilty of pitching yeast at too high a temperature (paranoid about infection and trying to get the yeast in asap). I noticed that my last couple of brews went into the fermentation chamber at around 26C so was probably 27-28C when I aerated!


Apologies for the long post, I want to get all the facts and am in a desperate position. This is holding back my brewing ffs!

Does this sound like oxidation or infection? Any thoughts/ideas where I can go next? Is there a nuclear sanitation option I could try? Anyone got any spare cobalt-60? :grin:
Click to expand...

not all yeasts would be happy with those temps but is doing a Weiss with mangrove jack baverian yeast you'd get bananas not old vegetables. If it's not DMS and wrong temp for yeast I look at your hops they can be vegetal.

sounds as if your sanitizing is ok. no gushers?
 
Sorry forgot to add, for this brew pitching temp was 22C. Not as low as I'd like but not excessive.
I do get some over attenuation, (this brew ended at 1.010) but never had a gusher.
My hops are always fresh. Casacade in this case.
Thx.
 
Have you bottled the new one? If so maybe you could send a bottle to someone who might be able to help identify the off flavour.
 
How old are your grains? When I first started AG I bought a 30kg bag of maris otter to save money, the first few batches were lovely but then they had an off taste all of a sudden when I got towards the bottom of the sack.
 
Nice idea Mattrick. But, all my grains are fresh (purchased pre-crushed from MM and used within the week).

I would be happy to send a bottle to anyone with experience in this area!

I'm not giving up on this but am running out of ideas what to try next. I think I'll try brewing without the fermentation chamber next time and go back to brewing in the kitchen. I might even try brewing in a different house just in case there's something in the air! I don't have pets, or a beard, dandruff or any flaky skin condition and I keep (cool) wort covered at all times. But, we do live at the bottom of a valley in the north of England. It's very damp and we do get a lot of mold and moss around the garden and shed.
 
I'd drop the oxygen for a starter. I tend to boil for 60 minutes lid off, chill with an immersion chiller, and once at around 20 degrees C I open the tap and let it run into the fermenter. Then I pitch the yeast (rehydrated for around 30 minutes) and put the lid on. I've never had an inactive yeast problem, and that seems to give them all the oxygen they need.

After that, avoid splashing of any kind; keep transfers slow and steady. If you've still got the off flavour, then I'd look towards other causes.
 

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