Discussion in 'General Beer Brewing Discussion' started by johnnyboy1965, Dec 2, 2013.
Contraversial (sp) I know, but it is the nature of the yeast beast to do its job
So what is your theory on this then?
You can't just post an opener with out giving your side of it. Or are you just lighting the blue touch paper and walking away, to watch at a distance?
Yeast, being a living thing, is subject to environmental pressures changing its response to its environment to suit it's own agenda be that survival of the gene through growth and replication or survival of the organism through dormancy.
"Stuck ferments" or rather dormant yeast exist. Stuck ferment tactics as described in the very good how to guide change the environment to illicit a response from the organisms.
Pretty basic environmental microbiology which has been harnessed by brewers and cidermakers for various effects over the centuries. In fact, the stuck ferment is engineered into the process of keeving to make sweet, naturally carbonated cider.
Irrefutable I'm afraid.
I've had several in wine, touch wood, the ones I thought I had in beer turned out to just be higher FG (and very tasty) beers.
My thoughts are like this....people who say they have a stuck fermentation often refer to eg "OG 1.040 stuck at 1.020". Therefore there must be viable yeast in the brew, to drop it by 0.020. The yeast has done its job, its consumed all the available sugars present in the beer. Yeast will not stop working if there are sugars available, ie ..if there is live yeast and sugar available it will carry on fermenting.
Sorry, no. You can have a stuck ferment, take the yeast from it and ferment something else with suitable conditions for that yeast. Likewise you can take a stuck brew and add it to a different yeast and have it chew down the sugar left behind.
The "stick" is when the yeast moves from a growth and replication phase to a dormancy phase where it hopes to ride out the current adverse conditions in the hope that they will change. In the case of keeving that's done by taking out all the other nutrients required for active yeast growth so it can't utilise all the sugar. It's not dead, add yeast nutrient and the whole thing would start up again.
Take the extreme end of fermentation - Brewdog's Ghost Deer at 28%ABV - all fermented! That (if I'm right on the theory) takes multiple fermentations with different yeast strains, each one carefully grown and conditioned for a particular stage of the fermentation, they all give up eventually and the beer is transferred to another yeast cake of a yeast grown to tolerate that particular level of (poisonous) alcohol.
Many stuck ferments in the pursuit of one crazy beer.
Even if it gets cold?
I personally think that most stuck fermentations are caused by the temperature being too low. At the start of ferment the conditions are ideal for the yeast to work....aerated wort, food, no alcohol present, fresh and healthy yeast.....a small temperature drop won't matter too much, and the initial stages are very exothermic too. But as the conditions deteriorate (in terms of whats best for the yeast), the yeast is more likely to drop out if it gets a little cold.
What advice do we normally give for a stuck ferment.......rouse gently and increase the temperature a little??
Every single yeast strain will carry on working if there is sugar present, you cannot stop it.....unless you add (I think its potassium sorbate) which kills off any live yeast.
If you brewed a beer with a bog standard yeast at 1oC, eventually it will ferment out.
Hi nice to know I'm not the only one who makes somewhat controversial posts. lol!
And my tuppence worth is that stuck is probably the wrong word, I think paused might be better, or even a hibernated ferment.
As you can re-rouse the yeast (usually)! And it could be that just leaving the wort/must to It's own devices will start it up again
at some point. Although good management 'should' help prevent 'sticking'.
My first port of call would be to take a accurate gravity reading. As home brewers tihs is impossible, but the best we can do is by using two or three different hydrometers. If you are now sure that your beer is at eg 1.020, then here is a little chefs tip.....taste it....believe me on this one......mix 1li of water and add 20g of sugar...take a sample of your beer, and taste test them side by side.
My above post is wrong and will not work...I didn't take into account of the bittering hops
But you can judge it by:-
1 x Li Plain water
1 x Li water plus 20g of sugar.
This might give you a beeter ides
Read my previous. Read about Keeving. Read anything at all about basic biology.
Yeast needs more than sugar. Yeast will stop fermenting when it runs out of ANY of it's limiting factors. It is not at that point dead. Further, yeast can (and do) create buds (like spores) which are really quite resistant to environmental factors. So while you may not have ACTIVE yeast you can still have VIABLE yeast which is NOT fermenting and will not ferment until the conditions are right for it so to do.
Rate for fermentation can be limited down to effectively zero by one or more factors:
- Temperature (both high and low)
- Fermentable sugar concentration (both high and low)
- Other nutrients (usually Nitrogenous chemicals and metals)
Combining these factors can stop a fermentation happily. Not kill the yeast but stop a fermentation. Once more, I'll return to keeving. The concept here is that the nutrient level is reduced such that the yeast can only process sugar down to a certain concentration, after that it just can't get it into the cell to be used, because it needs the other nutrients for that process. Add more sugar, you get more fermentation. But still down to that sweet FG. Add more nutrient and it will ferment out to dry.
THAT is a stuck ferment. THAT is why one, some or all of the techniques we use to start them up again work.
76 x 25li AG brews might prove you wrong...stuck ferments....Zero
Sorry 74..I cant count two of them
Sorry my mistake, 91 AG brews (documented)...never had a stuck fermentation
For a second there I thought you wanted a discusion... Don't feed the troll. :lol:
My thoughts too
Each of which, presumably, with the right level of nutrient, the right temperature conditions and healthy yeast.
So what your post actually is, "I've never had a stuck ferment so I think they don't exist". And you're still wrong.
It's just that you haven't created the conditions to stick one. That doesn't mean they don't exist.
FFS, just look at the information on the packets of various strains of yeast!! The labs tell you how well they attenuate! How much of the available sugar they will be able to consume before they stick! They all stick! They have been bred to stick at a level that gives a pleasing final product.
Ferment something out with Windsor, take the FG. Then drop it onto a healthy US-05 yeast cake. Then take the FG...
An engineered "stuck ferment" for a sweeter beer with Windsor.
For the final time. There are more factors involved than living yeast and sugar. Varying those CAN and WILL cause a ferment to stick.
And if you still don't believe me or several hundred years' worth of cider maker's experience get yourself two demijohns. To each add 4l of water and 800g of sugar. To one add two teaspoons of yeast nutrient. Add the same amount of the same strain of yeast to each.
Ferment out and let us know what we already know will happen.
Tell you what, I'll save you the trouble of a google:
http://scholar.google.co.uk/scholar?q=f ... CCwQgQMwAA
OK, then, so so called experts/troll hunters. You try to tell me about yeast..there is a member on this site "saycr, forget his name, who bviously studied micro/macro biology, s I did.
Not fuming...little disappointed, but its your loss. I gave my educated opinion
Do you honestly think that I am incapable of using a search engine...thank you for pointing me in the right direction
Thats your problem you didn't to begin with you were just looking for a fight, and now someone has given you a good well constructed argument backed up with third party research to corroborate, you back down.
We don't mind healthy debate on here even the odd verbal fist fight, but looking for a fight just for the sake of it serves no purpose.
Why don't you just pen down your thoughts on the subject and allow the brewing community to pick over it, that is surely what happens in the scientific world with publication of papers etc.
Separate names with a comma.