Yeast Cake Questions

[Bonneville]

Hey all! I've been home-brewing for a few years now, but have a renewed interest recently. Browsing the forums, I've learned a lot... like White Labs/Wyeast should really be used for starters rather than direct pitch, which is what I have been doing forever.

As I was reading about yeast, starters, etc., I hit a few threads on yeast cakes. I decided I want to give this a try. So, here's the plan: I have an IPA using Wyeast 1272 in the primary that's ready for a secondary. I was planning my next beer to be an English Pale Ale, and was thinking this yeast could work (probably a bit fruity, but I always seem to brew "hybrids" for one reason or another). The recipe OG for the IPA was 1.067 and I measured a 1.064, so I don't think I need to worry about too much alcohol for the yeast. (Expected FG is 1.016, but I won't measure that until racking to the secondary).

Having never done this before, I have some questions:

1) It sounds as though people have poured wort right onto the yeast cake. Does this mean just rack out old beer, add new wort, and aerate? Do we need to clean out kreusen ring and attempt to re-sanitize without disturbing yeast cake?
2) The trub at the bottom will include not just yeast, but also some settled grain & hop residue. (I filtered wort when adding to primary, but some always gets through.) Will this have much of an effect on taste? The IPA was heavy on Amarillo and the EPA will be Kent Goldings.
3) Any other words of wisdom? I recently did my first primary in a carboy with some surprises, so I figured I would "ask first" this time. The primary in this case is a bucket.

Thx.

 

[andre the giant]

I've reused a yeast cake several times. Usually, it has been something like putting a hefeweizen on top of a hefeweizen yeast cake, so there has been no problem. IPA to EPA may be a little backwards, (I would brew the blander style first, then the more flavorful or hoppy style second on the same yeast cake) but I don't think this is a stretch.

I'm not sure how the hops in the trub will effect the flavor although I would assume it won't have much effect since bitterness and flavor are mainly extracted from the hops during the boil. Also, out of the ounces of hops you put into the IPA, only a few fractions of that will actually make it to the fermenter. Unless the trub has been in the fermenter for weeks and weeks, It shouldn't impart any flavor to your brew.

I would go for it. Just brew the EPA, rack the IPA to the secondary, rack the EPA right into the fermenter and aerate. Your fermenter is already santitized enough, otherwise your IPA would probably be exhibiting some signs of infection. Don't worry about the sanitizing, krausen ring, trub or anything. If your experience is anything like mine, fermentation will kick in within a few hours and it will be massive. There are billions, trillions? of hungry yeasties in the trub, and when they find the good clean wort, they will go INSANE. Any possible contamination from the krausen ring won't have a chance against healthy yeast.

Use a blowoff hose. It is a must.

Disclaimer: its been a couple years since I tried this. I stopped brewing for a year or so.

 

[Bonneville]

Cool. I wasn't sure if it was literally as simply as rack - add wort - aerate. Sounds likes that's all there is to it.

Granted, going from strong to weak is backwards, but we'll give it a whirl.

Thanks!

 

[double_e5]

I wouldn't rack a normal gravity beer on top of a yeast cake. Usually, when people do this they are going from a normal gravity beer to a big beer.

If you want to reuse the yeast, I would just save some of it and pitch the slurry. That way you can clean and sanitize your primary and not have all that extra trub, krausen ring, etc. in there. You will also be pitching the correct amount of yeast.

 

[Bonneville]

Hmm - Makes sense. Maybe brew the EPA as normal and then do a monster IIPA onto the cake down the road.

If I pitch some slurry into the new brew, how do I know it's the "correct amount of yeast"? Also, I was under the impression that it is fairly tough to over-pitch for a homebrewer... but maybe I am way off on that.

 

[double_e5]

Here is a great link:

Mr Malty Pitching Rate Calculator

It will tell you how big a starter, how much dry yeast, how much slurry, etc.

It is difficult to overpitch, but one thing I would classify as overpitching is reusing an entire yeast cake when it is unneeded. You still want the yeast to go through a healthy reproductive stage. When you put a normal gravity wort on a yeast cake they don't go through that healthy reproductive stage which can lead to under attenuation among other problems. Keep in mind, it is better to lean towards pitching too much yeast than not enough.

Your example of brewing an EPA and then pitching a big IIPA would be perfect.

 

[llazy_llama]

1: You have it pretty straight. Just rack as per usual, then pour the new beer straight in there. Don't sweat the krausen, just leave it in.

2: The existing sediment shouldn't effect flavor assuming you're following the dark beer onto a lighter beer's yeast cake methodology. If you have a big Imperial yeast cake, you'd better be pitching a big Imperial back onto it. Something like a Cream Ale is going to come out funk-ay with a capital FUNK.

3: Words of wisdom? Hmm... How about "Holding on to anger is like grasping a hot coal with the intent of throwing it at someone else; you are the one who gets burned." -Siddhartha Gautama

Seriously though, I know the My Malty tool is a great one, but on a homebrew scale, it's almost impossible to overpitch yeast to the point of off flavors. I've never been able to pick out an off flavor from a yeast cake pitch, even in side-by-side comparisons using the exact same recipe. Rack that beer, pitch your new beer, then use the time and money you've saved to savor a homebrew!