Fermenting using previous batch yeast/trub?

I am looking to brew a mocktoberfest on Tuesday. I had purchased an extract kit with Wyeast 1007 and made a yeast starter, but it didn't take (too warm sitting on my counter I think). I have a cream ale in the primary with Wyeast 1056 fermenting right now. Primary should be done by Tuesday. Here's the plan, but I need to know if I should have some concerns.

1. Rack Cream Ale off primary to secondary (wouldn't normally do this, but want to use the primary for the mocktoberfest).
2. Dump mocktoberfest wort into primary right on top of trub/yeast cake at bottom of primary left over from cream ale.
3. Shake well and let that ferment the mocktoberfest.

Couple questions:
1. Should I remove the trub and yeast cake from primary and try to "wash the yeast"?
2. Are there concerns with sanitation with just dumping new wort onto old trub?
3. Will this actually work?

Gonna sub here. Doing this next weekend. I am assuming you just dumb the new beer in there and everything will settle out again. But is it recommended to aerate in the kettle? Or stir up the primary or what?

It will work. I did this for an imperial stout and it definately fremented. The only problem is, unless you're making a really high gravity brew, you are overpitching which can cause off flavors. But it does work. Try it and see for yourself.

EDIT: I did not wash the yeast cake, just cooled and transferred on top.

You can...but that's over pitching the yeast, by a lot. Yeast reproduction is essential for flavors, and with no reproduction required, no yeast flavors would be present. You could wash the yeast, make a starter, and pitch that into your next batch. Or if you are lazy and you feel that the trub is clean enough (like not packed with hop particles or other things you wouldn't want in your next batch), sanitize a small container (like around 1 cup in size), and scoop up a small amount of the trub and pitch that into your next batch. It's not very accurate, or the best process, but I have done that in a pinch, and it's better than pitching directly on the cake.

Well I have washed my yeast before it's not that big of a deal. I could bottle the first beer wash and then pitch a portion the next day when I brew. I kinda wanted to experiment with pitching on the yeast cake tho because I am planning on doing say an amaerican wheat then throwing a double/imperial IPA on top which sounds about right. This next beer however is a 3% hefe (first ag) and then a hopefully 5% dampfbier on top.

I just did something simlar.

I brewed a lower gravity Belgian Blonde. When that was done I bottled it while the boil was in progress of a Dubbel I was brewing. I took a couple of cups of yeast out of the fermenter, put it in a santized jar, while i cleaned the fermenter. When the wort was cool I just put those couple of cups of yeast that I took and pitched that.

I just pulled a sample after 3 weeks and it worked like a charm. Sample tasted great, finished a little lower than I expected. I am going to let it sit another week and bottle.

lestershy said:

It will work. I did this for an imperial stout and it definately fremented. The only problem is, unless you're making a really high gravity brew, you are overpitching which can cause off flavors. But it does work. Try it and see for yourself.

EDIT: I did not wash the yeast cake, just cooled and transferred on top.

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Well the cream ale I am brewing had an OG of 1.039 and I expect the OG of the mocktoberfest to be about 1.058-1.060 - not a big beer, but bigger than the cream ale. Is this still overpitching by far too much?

I use carboys, so I can't simply stick a sanitized spoon in and pull a cup or two out of the bottom. Seems like the best option would be to rack to secondary, pour 2-3 cups of trub into sanitized jar, wash yeast, then pitch the washed yeast into the new wort in the primary. Whadya think?

mhayden37 said:

Well the cream ale I am brewing had an OG of 1.039 and I expect the OG of the mocktoberfest to be about 1.058-1.060 - not a big beer, but bigger than the cream ale. Is this still overpitching by far too much?

Click to expand...

Yes, it would still be over pitching.

mhayden37 said:

I use carboys, so I can't simply stick a sanitized spoon in and pull a cup or two out of the bottom. Seems like the best option would be to rack to secondary, pour 2-3 cups of trub into sanitized jar, wash yeast, then pitch the washed yeast into the new wort in the primary. Whadya think?

Click to expand...

Yes