over pitching causing acetaldehyde

[robsan77]

I've done a brew recently where I experimented with over pitching. The yeast was a week old slurry of so4.

Fermentation was done after about 5 days. Og was only 1040.

But after being on the yeast for 2 weeks now there is a noticable amount of acetaldehyde present.

After a little, research it appears this is common from over pitching.
So in an attempt to get a beer ready quickly, it is now going to take longer before it is ready.

Doh!

 

[calumscott]

So is your take on this that for BIG beers dumping the wort onto an existing yeast cake is fine as it'll mature for a long time and the acetylaldehyde will diminish over the conditioning period anyway?

 

[robsan77]

In theory it should be ok. Especially if the yeast cake was from a lower gravity beer. But Id do some research to work out the correct pitching rate and go with that. Mr malty .com pitching calculator is good.

 

[robsan77]

The beer never cleared up and now has a cidery edge to it. Disappointing but a good lesson learnt.

 

[pittsy]

It could be caused from a few ways , 1 if brew is not left long enough for yeast to eat up the acetaldehyde , we should leave the brew either in 1 fv or just longer in 1st fv. But another way is infection so lets say that's not the problem. so as far as i now over pitching shouldn't cause it .

 

[robsan77]

I left this one on the yeast for weeks but it hadn't worked.

I have just worked out though that the yeast was from a batch of og 1054 and gone into a 1040 batch. I had always wondered about that myth.

I think that is probably the main contributor to the problem and overpitching made it worst.

I've had some infections in my time but this is definitely a load of acetylaldehyde.