Reusing yeast from primary only fermentations?

[hazedandconfused]

I dont think ill ever run out of questions for you guys here.
I plan on brewing a mocha porter tomorrow morning using wyeast irish ale yeast. Im going to do a primary only fermentation and let it sit about 15 days or so - so that i know itll finish and have had a bit of time to condition/clean up before i bottle. I was also hoping to do a stout and just pour the stout wort right on top of the yeast sediment immediately after siphoning the porter off. Does anybody think that this could be a bad idea? Most of what ive read about this procedure has been about people doing it right after siphoning to a secondary container right after the initial intense fermentation and i know nothing about using the yeast after the full fermentation.

 

[zyx345]

I'm actually planning on doing the same for 2 batches of Hefeweizen using the same yeast. From what I understand you can reuse the yeast but I believe it contains more cells so fermentation will kick off much faster and probably more vigorously. I've also heard that you don't want to do this if your prior beer is a high gravity beer, i.e. 1.075+.

This is an interesting site for saving the yeast cake without going through the process of yeast washing:

http://www.mikebeer.net/reuseyeast.htm

 

[Golddiggie]

Use Mr. Malty to figure out how much of the cake to keep in the fermenter for the next brew...

Personally, I don't pour right onto a cake. I harvest and wash the yeast before using part of it again. This way what it was used in previously doesn't really matter. There's a sticky in the yeast section about washing yeast...

On another note, I wouldn't just assume the first brew is done just because it's been 2 weeks... IF it's a low OG brew, it could be done. But, there's also a high probability that it will be even better if you leave it on the yeast for another week or two. IMO, a two week primary is a very short primary. A 'normal' OG brew, for me, stays on the yeast at least 4 weeks now. More often it's been turning into 5-6 weeks. Far better, IMO, to take a couple of SG readings, 2-3 days apart, to confirm it's hit a FG, and TASTE the brew before racking and bottling it up. Don't just assume that giving it ~14 days is enough time for the yeast to do all that they can for the brew... Yeast don't care about human time frames... They also don't work to our schedules. We need to adjust our schedules to allow them enough time to give us great brew...

 

[Airborneguy]

I pour right onto the cake when I am brewing and bottling/kegging on the same day and am making a beer that can use that same yeast. Otherwise, depending on whether I need any, I just sanitize a mason jar and scoop some yeast into it and throw it in the fridge. I don't see the need for washing unless you plan on re-using the yeast a ton of times. I then warm the mason jar up, and pour some into a starter wort before my next brew.

 

[Calder]

You can put your next beer right onto the cake. It will take-off.

But ....... You would do better to take the cake and pour it into several mason jars, and just use about a quarter of the cake. Put the other mason jars in the fridge and you can use them on other beers.

The reason for using only part of the cake is so it reproduces new cells. With a full cake, the yeast doesn't reproduce much bacause it is already at a large population, and the old cells can become stressed, and may slow down at the end. Also, when yeast reproduce, they set some of the yeast character (flavors) which will be missing if you use the whole cake. Over-pitching can also lead to increased fusels being created.

Sure use Mr.Malty if you can figure out what setting to put in. I just use a quarter of the cake, no starter required.

 

[brewit2it]

Short answer, yes you can pour your cooled wort of your next batch on top of the yeast cake from the prior batch with no problem. It has nothing to do with whether or not you used a secondary. And as long as it doesn't get infected you wont get any extra off flavors, fusels, etc. Just make sure you control the temps, use good ingredients and good clean technique and you will be fine.