repitching on slurry

I've never reused yeast before and want to try on my next batch. I understand that I can wash the yeast to remove the trub and other junk that accumulates. I also understand that I could repitch onto the slurry left in the bucket. My concern is that I don't filter out hops before I pitch and I leave them in the primary where they settle to the bottom during fermentation. Would it be bad to pitch onto this trub? Should I have filtered the hops before fermentation if I planned on fermenting another batch on top of this slurry?

Thanks in advance for the help.

I dont think it would be a problem personally. Hell ive had a vanilla bean in my trub ive used for my last 3 batches and ive had no problems yet with that. i think everything was probably extracted from those hops in the boil. even if there would be an effect from them it would probably be similar to dry hopping rather then contamination.

It is never a good idea to simply toss fresh wort onto a pile of trub and yeast.

In the first place there is simply too much yeast. A proper pitch is a definite, determined quantity of yeast. Overpitching is bad brewing practice. Most beers we brew benefit from yeast character (even lagers!); overpitching is a guaranteed way to remove that character. That makes mediocre beer.

In the second, have you looked inside that fermenter? Yuck! In my world, fresh wort goes into clean, sanitized vessels. Period.

I know many brewers knock out onto yeast "cakes" all the time and claim good results. I'm not calling them liars. I do challenge them to place one of their overpitched beers next to a beer that's been properly pitched and tell me which is better.

Hey, if it were really that easy, commercial brewers would do it. But they don't.

You're better off harvesting slurry, even if you don't bother to wash the yeast. Just scoop some slurry off the bottom of the fermenter with a sanitized implement and store the slurry in a sanitized Mason jar until you're ready to pitch. Don't wait too long, though, or you'll be building a starter.

Cheers,

Bob

Bob here is probably right with everything he is sayin, but that doesnt mean that it will turn out bad if you do it anyway. If you just want to dump it in I think you will still make great beer.

Pivot, you and I only disagree on certain levels. I think he'll make better beer if he uses good brewing practice. I don't mean to say beer made by knocking out onto a yeast cake makes bad beer, 'cos it doesn't. It just makes mediocre beer compared to properly-brewed beer, in my experience. Believe me; I've tried it. Blind tasting and everything.

Cheers!

Bob

So with either method, dumping onto the yeast cake or harvesting slurry and pitching a known amount, the hops in the trub will not affect my next batch, correct?

Thanks for the replies!

Bob said:

It is never a good idea to simply toss fresh wort onto a pile of trub and yeast.

In the first place there is simply too much yeast. A proper pitch is a definite, determined quantity of yeast. Overpitching is bad brewing practice. Most beers we brew benefit from yeast character (even lagers!); overpitching is a guaranteed way to remove that character. That makes mediocre beer.

In the second, have you looked inside that fermenter? Yuck! In my world, fresh wort goes into clean, sanitized vessels. Period.

I know many brewers knock out onto yeast "cakes" all the time and claim good results. I'm not calling them liars. I do challenge them to place one of their overpitched beers next to a beer that's been properly pitched and tell me which is better.

Hey, if it were really that easy, commercial brewers would do it. But they don't.

You're better off harvesting slurry, even if you don't bother to wash the yeast. Just scoop some slurry off the bottom of the fermenter with a sanitized implement and store the slurry in a sanitized Mason jar until you're ready to pitch. Don't wait too long, though, or you'll be building a starter.

Cheers,

Bob

Click to expand...

Jamil Zainashef recommends pitching onto a yeast cake in his brewcast episode for either a maibock or a dopplebock, I forget which. He's won a competition here or there, oh, and he has that pitching rate calculator thing. But you're right, its NEVER a good idea to pitch on a cake.

In my experience, a yeast cake can work just fine. I just stick to a couple rules that work for me:

A: Go from a low gravity beer to a higher gravity beer. Ie...an english mild to an ipa

B: a fairly light colored beer to a darker beer...keeping in mind rule A. Ie...an esb @5% abv to a strong porter @7%.

Just wanted to relate my experiences. I also tend to pitch on a cake that is low on hops with a beer that has a higher hop rate.

haha okay I think we have deviated from the OPs original question haha.

It seems he intends to pitch onto the cake as long as the hops wont damage his beer that may or may not be residing in said yeast cake

Bob said:

Pivot, you and I only disagree on certain levels. I think he'll make better beer if he uses good brewing practice. I don't mean to say beer made by knocking out onto a yeast cake makes bad beer, 'cos it doesn't. It just makes mediocre beer compared to properly-brewed beer, in my experience. Believe me; I've tried it. Blind tasting and everything.

Cheers!

Bob

Click to expand...

I completely agree with you. I guess if you want perfect brewing practice then yes I agree with Bob entirely and there are better ways to go about it. But the time saving aspect of pitching directly onto a yeast cake CAN be tempting and I have done it a few times without any dire consequences and made good beer. so its all up to you

Bob said:

It is never a good idea to simply toss fresh wort onto a pile of trub and yeast.

In the first place there is simply too much yeast. A proper pitch is a definite, determined quantity of yeast. Overpitching is bad brewing practice. Most beers we brew benefit from yeast character (even lagers!); overpitching is a guaranteed way to remove that character. That makes mediocre beer.

In the second, have you looked inside that fermenter? Yuck! In my world, fresh wort goes into clean, sanitized vessels. Period.

I know many brewers knock out onto yeast "cakes" all the time and claim good results. I'm not calling them liars. I do challenge them to place one of their overpitched beers next to a beer that's been properly pitched and tell me which is better.

Hey, if it were really that easy, commercial brewers would do it. But they don't.

You're better off harvesting slurry, even if you don't bother to wash the yeast. Just scoop some slurry off the bottom of the fermenter with a sanitized implement and store the slurry in a sanitized Mason jar until you're ready to pitch. Don't wait too long, though, or you'll be building a starter.

Cheers,

Bob

Click to expand...

As for the overpitching concern, I would never pitch onto a yeast cake for that reason... unless you're pitching a very large wort. I've used this method for a few fantastic imperial stouts. It's the very best method I've found for starting a beer that big (90+ points).

I would never consider it for something even marginally less than that.

I'd take that challenge by the way! The only problem is that my RIS never lasts as long as I'd like!!!

Zooom101 said:

So with either method, dumping onto the yeast cake or harvesting slurry and pitching a known amount, the hops in the trub will not affect my next batch, correct?

Click to expand...

Unless it's some insanely hoppy IPA yeast cake and your fresh wort is Mild or something, correct. I mean, you have to be sane about it.

Bob

Awesome. That's the answer I was hoping for. I'm going to plan on using Mr Malty's pitching rate calculator to determine how much slurry to use for my next batch. If time is a concern, I could always dump out about 75% of the slurry and pitch on top of the remainder. Please correct me if I'm wrong or have misinterpreted any of your responses.

Thanks again for the replies! I'm excited about saving $8.00 on each batch from here on out.

JoMarky said:

Jamil Zainashef recommends pitching onto a yeast cake in his brewcast episode for either a maibock or a dopplebock, I forget which. He's won a competition here or there, oh, and he has that pitching rate calculator thing. But you're right, its NEVER a good idea to pitch on a cake.

Click to expand...

Trying to decide if that's a passive-aggressive snark or not. I'll go with my gut and say, "Not."

First, Jamil is not infallible. While he's not technically wrong, some of us have more brewing background than homebrew competition wins.

Second, even with high-gravity lager beer, I can't think of a situation in which the dregs from a 5-gallon batch won't be overpitching - unless the fresh wort is 10 gallons of 1.100+ bock wort. Then, yeah, you might have a point.

The Rule of Thumb for pitching is 1 million active cells per milliliter of wort per degree Plato. Thus, for a wort of OG 1.048 (12°P), you need 12 million cells per milliliter of wort. There are 3785 milliliters per US gallon, or 18,925 per 5-gallon batch. Thus, you need 227.1 billion cells to properly inoculate the wort.

Fix et al. estimate approximately 1 billion yeast cells in 1 milliliter of slurry, due to trub and other non-yeast material (that number is massaged slightly based on personal experience). That number goes up when the slurry is washed - not important for the present example, but keep that in mind. Thus:

227 ml of slurry is required.

You'll forgive me if I consider an ale pail with 2" of slurry on the bottom contains just slightly more than 227 ml.

Even when considering a wort of 1.097 (23°P), you need ~435 ml of slurry. That's still about half of what I get in the bottom of an ale pail after a "normal" ferment.

So yeah, if you're brewing freaking gigantic beers, or doubling the batch size (brew length) and brewing a bigger beer, using all the slurry makes sense.

Still doesn't stop my "Look at that filthy fermenter OMGWTFBBQ!!!!11!!" button from being pushed, but I can't force anyone to be clean.

Cheers!

Bob

I tried this for the first time a month ago and the result was very good. I dumped a Belgian Strong Ale on top of the yeast cake from my IPA. If I had planned it out I would have done it in reverse because the 8oz of hops did impart some flavor to the Strong Ale, but I don't think any normal hop addition would make a huge difference. The Belgian had a very healthy, long fermentation and tastes great.
Experimentation is half the fun so go for it.