Advice on reusing yeast...

[mmmBeer...]

I was planning on making a new batch by pouring another batch of wort on the yeast cake.

However, I am ready to brew but the beer is not ready for secondary...it is still blowing foam and the fermentation is very active.

So my question is, can I pull off 2 pints of the krausening beer and use it like a starter?

[Fast_Eddy]

Originally posted by mmmBeer...
I was planning on making a new batch by pouring another batch of wort on the yeast cake.

However, I am ready to brew but the beer is not ready for secondary...it is still blowing foam and the fermentation is very active.

So my question is, can I pull off 2 pints of the krausening beer and use it like a starter?

I can't think of any reason why not - as long as the two beers are close enough in style to not affect the taste of the second beer.

[mmmBeer...]

The recipes are identical...Dad drank up most of my supply on his visit so I just wanted to get 2 simple ales going so that Wifey and I don't run out of beer. I have 2 empty kegs waiting for them!

[brewmonkey]

Even if they were not the same beer you could still use it provided you follow a few guidlines. You always want to pitch from a like beer or a beer with similar characteristics. You would never want to pitch from a Stout to say a wheat or a pale, but the reverse would be ok.

You would also not want to use the yeast if you ended up with a lot of trub from the boil going into the fermenter.

If you had an extended primary with the last beer, ie 2 weeks+ in primary. You may have some autolysis problems.

Be prepared to set up a blow off tube/bucket as the amount of yeast you will be using may provide for a very fast and vigorous fermentation, possibly cutting a day or two off the cycle. Just allow for a good diacetyl rest before racking.

[mmmBeer...]

Thanks for the reply…I am going to try it tonight.

I strained the wort after the boil so there isn’t that much trub.

It will be a week tomorrow that I brewed this batch…I forgot to make a starter so it was a little slow getting going (about 24 hours). I seem to have longer primaries than a lot of people on the board. I aerate really (plus I boil down to 3 gallons and top off) so I am not sure why my primaries last longer than others (usually about 8-9 days at about 69*F).

Can you explain diacetyl rest…I have seen this a few times and kept meaning to ask about it.

[brewmonkey]

Diacetyl is a by-product of most fermentations, and a lot of the yeast strains will tell you that the yeast will produce some diacetyl (in some beers it is desired). Once primary fermentation is complete, rather then racking it right away you allow it to "rest" for 24-48 hours at about 60-68F and the yeast will reabsorb some of the diacetyl they have produced.

Diacetyl will come across as butter/butterscotch in the aroma and flavor.

Now, there is also a a bacterial diacetyl that is highly undesireable. It is not a by product of the yeast but rather Enterobacteriaceae, a gram negative bacteria, and can ruin a beer. Once it is in the beer, there is no way to remove it and it will get worse with aging.

[mmmBeer...]

Thanks for the explanation. This was something I was doing totally by accident! I just wanted to give the beer a good chance to settle down before racking it.