10 replies to this topic

[sleepy]

So, I made Jamil's Evil Twin a couple of weeks ago, and fermentation is stuck at 1.030 (separate readings 3 days apart). I used US-05, which I think was a year old. And my aeration was questionable at best.My question is which of the following (or combinations thereof) do I use:- Fresh US-05- Nottingham (expiration of September of this year)- Amylase enzymeI only limit it to these three options because its what I have on hand.

[Deerslyr]

So, I made Jamil's Evil Twin a couple of weeks ago, and fermentation is stuck at 1.030 (separate readings 3 days apart). I used US-05, which I think was a year old. And my aeration was questionable at best.My question is which of the following (or combinations thereof) do I use:- Fresh US-05- Nottingham (expiration of September of this year)- Amylase enzymeI only limit it to these three options because its what I have on hand.

What was your OG? Also curious as to the mash temps, thickness, etc.IIRC, the enzyme will drop it completely and dry it out. My best advice would be to pitch the US-05, but... what was your OG???

[sleepy]

OG was 1.065, mash temp was 153. I was leaning towards pitching the US-05, but for some reason I thought that the amylase (not beano) would only take it so far. Then again, I don't have any idea how far it would take it.

[sleepy]

Oh, and thickness was about 1.25

[djinkc]

Have you tried swirling it and letting it warm up a few degrees? Since you have some more 05 I'd probably pitch that too.

Edited by dj in kc, 04 June 2010 - 12:32 PM.

[sleepy]

Yup, shook the crap out of it the other day, and its sitting at 71 degrees. I'll definitely shake it up again when I pitch

[BrewerGeorge]

Before you do anything more creative, you need to find out if it's actually stuck, or just DONE fermenting. Swirl up the yeast really well, draw a largish sample (pint or so) and bring it out where it's warm. Shake the crap out of it to aerate, and let it sit a day or two to see if it drops further. If it does, then there is room to improve, and you can add more yeast, yeast energizer and such.If it does not, then the yeast have just run out of simple sugars to eat - that would probably be some kind of mash/boil problem. In that case, the best advice I could give would be to brew another and shoot for a gravity less than 1.010 and mix the two beers.Gotta go now, I can elaborate further later when I have more time if you're interested.

[sleepy]

I am interested, and I am curious to why the enzyme wouldn't work (obviously, I don't have any idea how amylase actually works)

[BrewerGeorge]

I am interested, and I am curious to why the enzyme wouldn't work (obviously, I don't have any idea how amylase actually works)

Amylase (alpha and beta) are enzymes that break up starch molecules and turn them into sugar molecules. A mash that favors beta amylase (lower end of sachrification range) will make more simple sugars and be more digestible by the yeast. A mash that favors alpha (higher temps) will make a higher proportion of more complex sugars that are less digestible by yeast. So unless you really screwed up the mash and boil and have starch in the fermenting beer, amylase isn't going to do anything at all.You're probably thinking of alpha galactosidase AKA Beano, not amylase. Galactosidase breaks up the complex sugars that alpha amylase produces and breaks them up into simple sugars that the yeast can then eat. (Note that alpha galactosidase does not occur naturally in beer production.) Alpha galactosidase can be used to change a beer that is truly stuck, but that change is not necessarily going to be an improvement. Actually, I'd say it will rarely be an improvement. The problem with it is that it doesn't stop converting, and the yeast don't stop eating the simple sugars it produces. Those indigestible sugars are desirable. They are what give beer it's body, mouthfeel, and residual sweetness. Galactosidase, given enough time, will turn any beer into thin rocket fuel. There's no way to stop it except heating the beer, which is basically impossible at the homebrew scale. My advice is to avoid it.A little theory:What I said earlier about testing a sample to see where you're really at is important. The symptom you describe as "stuck" - fermentation seemingly finished 20 points higher than expected - actually has two very different causes. The first is that something strange happened to the yeast, causing them to stop fermenting even though the beer still has sugars in it that they could digest if they hadn't had a failure. This is the condition that can be helped by adding fresh yeast, krausening, yeast energizers, etc.The second cause is that the yeast have done all they can do to a particular wort, but there just aren't any sugars left that they are capable of digesting. High mash temps or any other mash condition that emphasizes alpha amylase, excessive kettle carmelization, old LME or simply less fermentable extract in general can all cause this problem. Adding extra yeast won't do a thing to these "stuck" batches* because the yeast didn't fail. Something went wrong in the process. These are the ones that drive people crazy and cause them to add things like alpha galactosidase.*Adding lager yeast to a stuck ale can sometimes drive a beer a few points further down because lager yeasts are capable of eating the three-chain sugar molecules that ale yeasts cannot. I believe some wine yeasts are capable of this, too, but don't hold me to that. Champagne yeast is usually a blend that contains lager yeast, which is why some people get a small benefit from pitching Champagne onto a type 2 stuck ferment.

[sleepy]

George, in two paragraphs you managed to explain a concept to me that I've been trying to understand for the better part of a year.ThanksOh, and I added another pack of US-05 last night, its bubbling away happily now.

[sleepy]

Also, a note towards the forum itself.I know there's been some talk over the year concerning membership growth (or lack thereof). I just wanted to say that I posted a similar question on HomeBrewTalk, and didn't receive a single reply. I don't know if its because I have a low post count or just that people didn't care to answer another stuck fermentation question, but I had thought that due to the sheer volume of people and posts on that forum I'd at least get some sort of response.But here, not only did I get opinions and advice, I received the technical reasons why one method would work, and how exactly a very complicated process works (in so far as that people mention amylase all the time, but never seem to be able to explain what it does or why).I guess the short version of this post is:- You guys rock- Smaller is way the hell better