Lack of AG violent fermentations

I used to have a lot of airlocks blow off, or get filled with the foam/krausen from my beer when I was an extract brewer. Since I've gone AG a year ago I have not had a single problem with foam/krausen overflow from violent fermentation.

Is this normal, or am I doing something wrong(i kinda liked the violent fermentations)? Is it the protiens or natural oils that keep the fermentation at ease?

thx

Aeration, maybe?

If you were topping off partial-boil extract worts with bottled or tap water, you were adding a lot of O2 to the wort.

What are you doing to your AG batches to aerate them?

Was this an all malt recipe ?

Kai

cweston said:

Aeration, maybe?

What are you doing to your AG batches to aerate them?

Click to expand...

along the same line of O2 reasoning:
What temp are you cooling to? O2 solubility is greatly effected by temp.
The lower the temp, the more O2 you can dissolve, the more yeast can grow (divide), the faster the kickoff....

I have noticed the same thing, my only blowoffs have been extract or mini-mashes with a lot of extract. My guess would be that the sugars in extract are more uniform, so the yeast adapt to them faster. Alternately, my high gravity ales always have extract in them and those are the only ones that blow.

Aeration and starters are the two main things that help active ferments.

I use an aquarium air pump, with an inline filter to a metalic airstone. I let it run until it start sto foam out of the top, which is ussually around 2 to 3 minutes.

cweston said:

Aeration, maybe?

If you were topping off partial-boil extract worts with bottled or tap water, you were adding a lot of O2 to the wort.

What are you doing to your AG batches to aerate them?

Click to expand...

I havn't noticed that adjuncts affected it eigther way.

Kaiser said:

Was this an all malt recipe ?

Kai

Click to expand...

digdan said:

I use an aquarium air pump, with an inline filter to a metalic airstone. I let it run until it start sto foam out of the top, which is ussually around 2 to 3 minutes.

Click to expand...

Is that what you were doing for the extract batches as well??? 2-3 minutes is way short of what I've seen recommended... 30-60 minutes is what I see quoted when using air, 1-2 minutes is for pure O2...

I've taken to transferring my cooled wort into my 7 gallon plastic bottling bucket, covering and running the air pump for 30 minutes or until the foam reaches the top of the bucket, which ever takes longer... I then transfer from under the foam into my carboy...the foam contains trub and break particles, so it's ok to get rid of part of it (this is the principle behind a "flotation tank"; the aeration of the wort and the removal of trub and break material at the same time)

A little info on yeast and aeration is here: http://byo.com/feature/177.html

hope that helps some,

later,
mikey

I'd bet you are under-pitching. Step up that starter once or twice before brew day and then see what happens.

You mean


Not really violent, more slightly boisterous (but definitely all grain)

-a.

Dude said:

I'd bet you are under-pitching. Step up that starter once or twice before brew day and then see what happens.

Click to expand...

Well here is my situation. It seems my beers have an abundance of acetaldehydes and my efficency is allways way below normal( later found that my crush was way off). I do know that I under aerate, but I've under aerated some violent fermentatons before. But even the batches that I pitch a lot of viable yeast seem to just froth up and die back down in a couple days.

Show me way Dude

Well, lets recap.

for a good fermentation yeast needs the following:

- good pitching rate of healthy active yeast (should be taken care of with using a starter)
- sufficient O2 (this might be a problem, but you said that you underaerated violent fermentations before)
- freely avaibale nitrogen (FAN) (this comes from the malt. Mashes high in adjuncts can have a deficiency here. But if you use good pale malt, you should get more than enough for your yeast even w/o making a protein rest)
- trace minerals, Zn in particular is necesary for a good fermentation. (But an all malt mash should supply enough)
- fermentable sugars (There should always be enough in the wort to get a good fermentation if you had conversion).

Since you seem to get good fermentations with extract, I suspect problems in the recipie/mashing of your beer.

To pinpoint the problem, try the follwing:

- Make an all barley malt (pale malt, as this is well modified) AG ale
- add some yeast nutrient to the boil. I'm not a big fan or doing this, but it might help finding the problem.
- pitch a 2 qt starer at high Kraeusen
- aerate sufficiently (20 - 30 min with air or 1-2 min with O2) at a wort temp below ~75F

If you now get a violent fermentation, it must have been a yeast nutrient defficiency in the mash. This is pretty unlikely with all malt mashes, but I can't think of anything else right now.

Kai

My last batch was the 1st one i tried with a starter. It blew its top twice. I just recently tasted the 1st bottle from it, and its very good! But i was trying to make a higher gravity beer, and it seems about normal. One of the things I did after a top blowing off the fermenter was to scoop out some of the foam at the top, in hopes of preventing another explosion. Was I scooping out a bunch of yeast? Might this explain the lower alcohol content then i intended?