Acetaldehyde?

[dlowe1992]

Morning posters,

I’ve been trying to pin down some off flavours in a batch of pale ale. Simple recipe.. pale Malt / Goldings SMaSH. 5L batch. Fermented with half a packet of MJ’s Liberty Bell which I rehydrated.

Didn’t taste right from the get go so I repeated the brew a couple of weeks ago and have just bottled. Again 5L, this time fermented with CML Midland. Again, half a packet. Same off flavour straight out of the fermentor. I’d best put it as a cider flavour, hence guessing acetaldehyde?

Having said that, it’s surprising how hard it can be to pin down an off flavour..

No note off the off flavour on brew day so definitely occurring during fermentation.

I’m fermenting at room temp 21 deg or so. I know this is at the top end of temp for both these yeasts. I’m guessing high temps are causing the issue, especially as exothermic(?) temp rises are probably taking it even higher. Both brews fermented quickly and fairly aggressively.

I’m thinking issue is temperature and possibly over pitching and fermenting too aggressively? Would I be on the right track?

Both brews were left in the FV for two weeks and didn’t seem to clear up the off flavours.
Worth noting no trace of this in the Vienna pale I fermented with CML 5 or APA I fermented with M44. Both happy at slightly higher temps.

Apologies for the long winded post. Wanted to get everything down. Any other suggestions to root cause would be welcomed..

Ta,
Dan

 

[RichardM]

21c shouldn't be a problem.
I wonder if you have an infection in the fermenter that has carried over from one brew to the next.
Have you brewed anything in-between these two?

 

[Sadfield]

6.5g in a 5L batch is a lot of yeast (close to a double pitch), and whilst the temperature isn't a problem it will contribute to the fast vigorous fermention. I suspect your yeast is flocculating too early as a result, and not metabolising the acetaldehyde it creates. I'd recommend using a pitch rate calculator.

Presuming CML Midlands is Notty and CML 5 is US05, the later being less flocculent may explain why it returned a better result.

https://beerandbrewing.com/off-flavor-of-the-week-acetaldehyde/

 

[Twostage]

According to the MJ site Liberty Bell produces fruity esters and it's ideal range is 18-23. So maybe you should expect a little apple flavour. I don't think a 5 litre batch will produce more than a couple of degrees of heat, my 21 litre batches rarely get more than 2.5 degrees above external temperature.

Exposure to air ?

Not sure if that helps, just adding to the thought process.

 

[dlowe1992]

Thanks all.

@RichardM, I thought after the first batch it may be infection, which was partly why I did another..
Second batch was fermented in a different FV, a 5L ashbeck bottle. Opened for the brew itself, soaked in steriliser, sanitiser and rinsed thoroughly…

Possibly something in that @Sadfield. Benefit of the ashebck bottle, I could see what was going on and did seem to clear quickly and form a good cake at the bottom.
Would rousing once a day rectify this in another batch?

@Twostage, a little apple flavour I would t mind, this is bordering on pungent. Gets you in the nose before you taste it.
In theory, would fermenting at the lower end of temps produce a cleaner finish?

I ask as I’ve been testing out the eaves in our bedroom. They’re holding a steady (edit) 16deg at the moment so thinking of sticking my next batch in there and seeing if fermenting at the lower end changes things…

 

[Sadfield]

Would rousing once a day rectify this in another batch?

It could, but may not be necessary with the correct pitch rate.

 

[dlowe1992]

Have given this some more thought, and, in a rare happy occurrence, having a beer may have been the answer.
Had a bottle of this at the weekend and I could detect, at a lower (and much more palatable) level, the flavour and aroma I was finding off putting in my own beer.

It made me wonder if I was actually getting a whole bunch of esters. As in, more than desirable (at least to my taste) due to over pitching / high temps. I haven't used a 'British' ale yeast before. Only brews to date have used M44 or CML 5 / US05.

As a comparison point, I've done a similar small batch brew using US05. If only to see if this change eliminates the flavour. 4 grams to 6 litres of wort.
Happily fermenting away so will update on results..

 

[Hazelwood Brewery]

When using Liberty Bell at warmer temperatures I think esters of red apple are likely. I also think @Sadfield might have a point regarding pitching rates.

You could try pitching at a lower rate and fermenting at a lower temperature (maybe 18-19 would suit you better). You might also prefer US-05 to Liberty Bell if red apple esters are not to your liking, US-05 is pretty neutral.

I use Liberty Bell in all English ales but I do fermentvat the lower end of the temperature range. The esters *may* fade a little given a couple of weeks or so.

 

[dlowe1992]

You might also prefer US-05 to Liberty Bell if red apple esters are not to your liking, US-05 is pretty neutral.

That was my thinking. I get the feeling the flavour would be enjoyable at a much more subtle level.

If I notice a marked difference then I can be reasonably confident I’m on the right track.

I have a cupboard holding steady at 16 deg which I’d be tempted to do a trial batch in to see the difference. I believe midland from CML should be ok at that level…

I think for now I’m better focussing on my own process and improving / learning whilst using a fairly neutral yeast which I know to have been successful for me..

Thanks for the help

 

[Sadfield]

This is worth a listen, covering acetaldehyde, pitchrate and maturation.

https://podcasts.google.com/feed/aH...TQtMGQ3MC00MmI4LTg0ODQtYzJiZWM5ZDAzNTYw?ep=14

 

[Twostage]

I have a cupboard holding steady at 16 deg which I’d be tempted to do a trial batch in to see the difference. I believe midland from CML should be ok at that level…

I'm sure it will. The last batch of bread buns I made I proved the dough overnight in the fridge rather than the usual hour or so at room temp. Yeast have optimal temperature ranges but will still work below that, only slower.

 

[dmtaylor]

Esters indeed. Not acetaldehyde, which is extremely rare now in the mid 21st century.

 

[dlowe1992]

Checked the SG on my new batch fermented with US-05 today. It’s pretty much done.
No trace of the overpowering off flavour so it seems we have our cure. In fact, it was bloody lovely!
Thanks for the advice all, happy chap this eve!

 

[YeastFace]

Esters indeed. Not acetaldehyde, which is extremely rare now in the mid 21st century.

Not doubting you in the slightest, but why do you say that? Better quality of yeast available to the homebrewer?

 

[dmtaylor]

Not doubting you in the slightest, but why do you say that? Better quality of yeast available to the homebrewer?

Yes! Plus a more educated homebrewing community constantly stressing the importance of pitching plenty of healthy live yeast, instead of the old days with greater tendancy to straight-pitch a smaller pack of yeast that sat in a shop for who knows how long. It can still happen, but... it's much less common.

 

[Sadfield]

Yes! Plus a more educated homebrewing community constantly stressing the importance of pitching plenty of healthy live yeast, instead of the old days with greater tendancy to straight-pitch a smaller pack of yeast that sat in a shop for who knows how long. It can still happen, but... it's much less common.

Being less common doesn't exclude it from being the issue though. Especially when the OP has already indicated a considerable over pitch.

 

[dlowe1992]

Thanks all for the advice.
Aforementioned small batch done with US-05 was bottled a week ago and I’ve cracked one for an early taste.

Much more to my liking and rather moreish! Gonna be a challenge to leave the other bottles for a few more weeks to condition

The fact I got to hear before a photo probably speaks volumes…

 

[foxy]

Morning posters,

I’ve been trying to pin down some off flavours in a batch of pale ale. Simple recipe.. pale Malt / Goldings SMaSH. 5L batch. Fermented with half a packet of MJ’s Liberty Bell which I rehydrated.

Didn’t taste right from the get go so I repeated the brew a couple of weeks ago and have just bottled. Again 5L, this time fermented with CML Midland. Again, half a packet. Same off flavour straight out of the fermentor. I’d best put it as a cider flavour, hence guessing acetaldehyde?

Having said that, it’s surprising how hard it can be to pin down an off flavour..

No note off the off flavour on brew day so definitely occurring during fermentation.

I’m fermenting at room temp 21 deg or so. I know this is at the top end of temp for both these yeasts. I’m guessing high temps are causing the issue, especially as exothermic(?) temp rises are probably taking it even higher. Both brews fermented quickly and fairly aggressively.

I’m thinking issue is temperature and possibly over pitching and fermenting too aggressively? Would I be on the right track?

Both brews were left in the FV for two weeks and didn’t seem to clear up the off flavours.
Worth noting no trace of this in the Vienna pale I fermented with CML 5 or APA I fermented with M44. Both happy at slightly higher temps.

Apologies for the long winded post. Wanted to get everything down. Any other suggestions to root cause would be welcomed..

Ta,
Dan

Was the 21C the fermenter or ambient? Yeast can raise the temperature from ambient as much as 7-8C yeast-dependent, so if the 21C was ambient you can guarantee the exothermic reaction will take it higher. The last batch I pitched too high and the next day I knew I had ****** up just by the smell. It finished quickly and I am leaving it in the fermenter a while longer. Sometimes esters can subside but I am not holding my breath. I think this batch will not be worth bottling.
https://byo.com/article/fermentatio...st growth and,the early days of fermentation.

 

[MashBag]

@dlowe1992

I can't help but think we are all in the dark a bit. You mention loads of "could be's" , but you don't describe (or I missed it) the off flavours?

 

[Twostage]

Was the 21C the fermenter or ambient? Yeast can raise the temperature from ambient as much as 7-8C yeast-dependent, so if the 21C was ambient you can guarantee the exothermic reaction will take it higher. The last batch I pitched too high and the next day I knew I had ****** up just by the smell. It finished quickly and I am leaving it in the fermenter a while longer. Sometimes esters can subside but I am not holding my breath. I think this batch will not be worth bottling.
https://byo.com/article/fermentatio...st growth and,the early days of fermentation.

When I monitor the temp of mine they tend to rise around 3c. Never had one go 7-8c but as you say, it could be some yeast are little tearaways