Stuck Ferment

[vlbaby]

Kai, what exactly is amylo? I have an oatmeal stout that looks stuck also, and I wouldnt mind trying this stuff too if it works. Is this available at the hbs?

vlbaby.

 

[T.D.]

Amylo is an enzyme that, in very crude terms, "feeds" yeast and keeps them kicking along. From what I understand it isn't exactly the same as "yeast nutrient" but its similar in that it promotes higher attenuation. All things being equal you should get a drier beer if you use amylo enzyme. If your brews are prone to pulling up early (my last few have stopped at around 1.020) then the idea is that the enzyme will keep it going that little while longer - hopefully to the point where you would have liked it to stop. I have been told that under most circumstances it will get your beer down about 5 points further, but I have no idea if this is correct or not (I would imagine that in a higher gravity brew it would probably be more effective than a low gravity brew).

I threw some in my most recent brew because I don't want another FG of 1.020 - I am looking for 1.015 or lower. Today is the fifth full day its been in the fermenter and its still bubbling away quite strongly.

 

[Guest Lurker]

Amylo is an enzyme that, in very crude terms, "feeds" yeast and keeps them kicking along.

[post="67124"][/post]​

Not really.

An enzyme is not a nutrient or a living thing, it is just a chemical which acts as a biological catalyst. A catalyst is just a thing which makes some kind of chemical reaction go way faster, without actually participating in or being changed by that reaction. Enzymes usually work because the shape of the molecule happens to link in a special way to one of the molecules in the reaction and cause it to break into smaller bits.

So amylo enzyme is useful if you have too many long chain sugars and starches in the wort, which are too big for the yeast to use, as it beaks the big molecules into small bits the yeast can get at much faster and easier.

If a ferment is stuck beacause of poor yeast health, while there is fermentable stuff left to eat, then new yeast is the solution. If a ferment has stopped because the yeast are all itching to eat, but there are only complicated molecules left as food, then an enzyme will make a difference. In my experience adding amylo to a normal wort results in a low body, high alcohol, unbalanced beer, which may well finish less than 1.00. In Kais case he had investigate the yeast health options before resorting to the enzyme.

 

[T.D.]

Not really.

An enzyme is not a nutrient or a living thing, it is just a chemical which acts as a biological catalyst.

[post="67135"][/post]​

Hence my statement "From what I understand it isn't exactly the same as 'yeast nutrient' but its similar in that it promotes higher attenuation.".

As you also mentioned, an enzyme actually does lead to more sugar being fermented out, so its not purely a catalyst - it doesn't just make the fermentation happen faster, it also leads to more sugar being attenuable.

I was also a little skeptical about whether an enzyme would help get the FG down when temperature is the problem. But all signs suggest that it will indeed work (based on the way my current brew is shaping up). It also seemed to get Kai's fermentation back up and running (btw, I am not convinced that bad yeast is Kai's problem, given the extra yeast that was pitched with no success. The small batch size also makes it particularly susceptable to temperature fluctuations - I think this is most likely the cause of the high FG. A lot of people are struggling with FGs at this time of year)

Fingers crossed it works for all of our sakes!!!

Cheers.

 

[Bilph]

Amylo is something of a final desperate step. It's used in a lot of kit lagers to rip through some of the "body" sugars, as explained by G.L. Using it just to restart a stuck ferment risks changing the flavour profile, albeit slightly, and I believe can actually leave the unfermented sugars from the stuck ferment still unfermented again having an effect on flavour and actually risking bottle bombs as well. (I'm sure I read that last bit somewhere, but couldn't find it on a quick search, so correction/confirmation is accepted/appreciated.)
You should try to correct a stuck ferment firstly by correcting the problem which got it stuck. The two most common are probably temperature - especially in colder weather - and yeast flocculation.
I'd suggest the steps you take are to raise the temperature slightly, and gently rock the fermenter to resuspend yeast.
Next step is to pitch a little more yeast, especially a high attenuator.
Again, as G.L. pointed out, Kai took these steps before resorting to amylo.
Amylo would be something that I'm personally unlikely to ever use.

Edit: Another important factor - again in colder weather - is to make sure you are reading SG at the appropriate temperature. Taking an SG at a colder temperature than your hydro calibration temp will raise the SG and may well appear to indicate a stuck ferment.

 

[T.D.]

Amylo would be something that I'm personally unlikely to ever use.

[post="67141"][/post]​

But what if you get the urge to make a low-carb beer Bilph???

 

[Bilph]

T.D. Posted Today, 01:21 AM
QUOTE(Bilph @ Jul 14 2005, 11:15 AM)

Amylo would be something that I'm personally unlikely to ever use.







But what if you get the urge to make a low-carb beer Bilph???

Full strength, full carb, full flavour only for me at the moment T.D - at least for as long as the medical tests keep coming back with favourable results.

"... something that I'm personally unlikely to ever use."
As ever, to each their own. :beer:
Cheers.
:chug:

 

[T.D.]

Hahaha, well said! An FG of 1.010 to 1.015 is what I'm after. My last brew has 0.5kg of dark munich and 0.425kg of dark crystal in it so the old FG will be a tad on the high side anyway I should expect - amylo or no amylo!

Here's to good health!!! :beer:

 

[Kai]

Since this has popped up again, I thought I would add an epilogue to this piece.

I was very surprised that the amylase did not drop my gravity to sub-1.000 levels. I added half a sachet, and it dropped and stabilised somewhere in the 1.0lowteen region (I neglected to take notes). I then added the rest and it dropped down to 1.00* (again, no notes). Even though it had stabilised, there was still some fermentation left in it, as my (PET) bottles ended up over primed even though I added only 4g/L sugar, but at least I could crack and reseal the caps easily enough. The krausen from the starter I added was still present, and there was a lot of yeast still in suspension despite leaving it for a while in an attempt to settle it, and fining it with gelatine. In bottle it is very yeasty and will need a long time to settle out. I may degas a sample and take another reading to see what the SG is now.

The hops don't taste too bad, though.

 

[T.D.]

I am aiming for around the 1.010 to 1.015 range, which is 5 to 10 points lower than the FG my last 3 brews stopped at. I am hoping it doesn't go any lower than that. I think I might leave this one in secondary for a while given the fact your brew seemed to still have activity even after bottling.

How long did you have the brew in primary and secondary for Kai? I'll be very disappointed if my amber ale ferments out to zero!

 

[Kai]

A bloody long time, TD.

It's now finished at around 1.000

 

[sosman]

I have used enzymes once, in a poorly attenuated wit beer. It did help but I only used a few drops, I have heard anecdotal evidence (and Kai's story would support this) that you can end up with something so dry that it is no better to drink than the underattenuated thing you started with.

 

[Kai]

Actually, for how dry it is it's not too bad. However, it might taste different if the bloody yeast ever settles out.

 

[T.D.]

Well I sure hope mine pulls up before 1.000!!! I just had a taste and it should be a great beer if it doesn't keep going too long. I would guess that its around 1.020-1.025 at the moment, although I haven't done a hydrometer reading. The scary thing is that it the bubbling really hasn't slowed down at all yet and it's been in primary for 5 days now.