over pitching yeast

If it is possible to "over pitch" yeast (in otherwords, pitch too much yeast), what are some guidelines for what is too much yeast, and what is the result of over pitching? I would like to pour a Rogue Mocha Porter clone onto an existing yeast cake of WL051 (California V). The cake is in a primary that an IPA has been sitting on for nearly three weeks. Should I be concerned about over pitching? I am aware of the Mr Malty pitching calculator, I have it bookmarked.

we have discussed this extensively in other threads, and there is a huge debate about overpitching, the search function is great for finding this type of information. I pitch on top of yeast cakes and don't find any major flaws from overpitching, so I say don't worry about it. But that is just my opinion, others have varying opinions; and don't be fooled, they really are opinions and based on personal experience etc....

Yeah, who is it that said that most of us grossly UNDER pitch yeast? I figure pouring the wort right onto the cake should be A-OK.

I don't do it ONLY because I never brew that close together. I brew after week 1 I transfer into secondary and put back into the fermenting fridge and then let hang out there for a couple of weeks. Only after I keg do I have room in the fermenting fridge for another batch.
A bunch of people here on HBT do just that, dump directly onto the yeast cake. I say go for it you aren’t going to over pitch.
Cheers
JJ

Donasay said:

But that is just my opinion, others have varying opinions; and don't be fooled, they really are opinions and based on personal experience etc....

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Weeeeeeel....no. They're not. While mine is an opinion based on personal experience, that opinion has the fortunate circumstance of being backed by decades of published brewing science, as well as hundreds of years of recorded brewing experience, which says that overpitching is as bad as underpitching. That takes it out of the realm of opinion and into established fact. Sorry.

KayaBrew, I suggest you harvest some of the slurry from your WLP051 cake - great yeast, BTW - and use the Mr Malty calculator to determine how much slurry to pitch. You don't have to wash the yeast, so long as you use it within a week or two. Just sanitize a clean Mason jar and scoop out some slurry. Consult the Mr Malty calculator beforehand so you can overshoot your requirements by about 50%.

Then clean your fermenter. That's my biggest beef about knocking out onto an intact cake: putting fresh wort into a filthy fermenter just gives me the heebies. I know all the arguments, I know - it's just nonsensical that you can look at all that gunk and call it 'clean'. [shudder]

KayaBrew said:

Yeah, who is it that said that most of us grossly UNDER pitch yeast? I figure pouring the wort right onto the cake should be A-OK.

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I'm one of the ones who talk about grossly under-pitching. In fact, I talk about homebrewers rarely taking the time to properly manage fermentation, part of which is to pitch an appropriate amount of yeast. That means neither over- nor under-pitching. Can you make beer without paying close attention to your yeast? Yes. But the conscientious brewer carefully considers all of his ingredients and techniques and how they interact. What drives me to distraction are those brewers who will carefully study and painstakingly select the choicest malt and hops, then delve deeply into water chemistry, then sift through the White Labs and Wyeast catalogs for the perfect yeast strain; once all that's done, they just toss in a smack-pack or vial - or pour their fresh wort onto a cake - and call it a day. All that knowledge gained, all that effort expended, just to stop short because they don't understand or even care to understand fermentation management.

I say it plainly, without intending offense: Knocking out onto a yeast cake is perceived as an advanced technique. It is nothing of the sort. It is a technique used by people who don't really understand fermentation management or don't care about the impact of pitching rate on their beer. (That last is for people who have tried the technique and not been bitten in the arse by it yet.)

Cheers!

Bob

Another thing to consider, and this is just from reading and research, not experience (perhaps someone can back me up or shoot me down?), but depending on the IBU count of your IPA, you may run into issues with the yeast not being able to do their job because of the hop oils that have coated the yeast cells.

I'm sure there's more to it, I just can't quickly find where I found that info while at work.

Another informative response, Bob. Thanks for taking the time, I will be taking your advice!

Sure thing! Harvesting isn't hard, and if you do it correctly you can pitch out to ~10 generations.

Have fun!

wrong thread.

KayaBrew said:

If it is possible to "over pitch" yeast (in otherwords, pitch too much yeast), what are some guidelines for what is too much yeast, and what is the result of over pitching? I would like to pour a Rogue Mocha Porter clone onto an existing yeast cake of WL051 (California V). The cake is in a primary that an IPA has been sitting on for nearly three weeks. Should I be concerned about over pitching? I am aware of the Mr Malty pitching calculator, I have it bookmarked.

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In an effort to specifically answer your question;

1) yes, it is possible to over-pitch
2) as previously stated, short of counting yeast cells, the average home brewer has the Mr. Malty yeast calculator or other calculators available online/in brewing software.
3) over-pitching can result in a less-estery, less ale-like beer because there is no need to the yeast to multiply (because there's more than enough to do the work already).
4) the RMP has an OG of ~ 1055? and your IPA was probably about the same? If so, then you are probably over-pitching. The good news is that the RMP doesn't have a huge need for an estery profile and does have a fairly strong malt flavor profile.

Bottom line?

Can you rack onto the IPA yeast cake? Yes, you can
Would I do it? No, I wouldn't
What would I do? At the very least, I would wash my yeast and try to pitch the correct amount according to the tools at my disposal.

I'm a big fan of trying to get things as close to ideal as possible. Fermentation is one of the biggest factors in the flavor/quality of our beer. Why would I buy expensive ingredients and take a whole day to pain-stakingly brew, only to not care about the proper yeast rate and fermentation process? I use Mr. Malty every time and ferment in a temp-controlled chamber.

This is something I have wondered about myself. So just to see what would happen I brewed up a 2 Gallon 1050 OG IPA and dumped in a full 11g package of Danstar Windsor (re-hydrated). I will update in 5 more days with my findings to that point and hopefully 7-10 days later with those.

From what I know it's possible to overpitch but the ramifications from doing so are less detrimental to your beer than those from underpitching.

I've pitched onto a whole yeast cake before but would never do it again. I either wash the yeast or save 1-2 cups (depending on both the "original" beer and the style going onto the cake) of slurry for pitching. You want to pitch enough yeast to ensure a healthy fermentation while making the yeast you do pitch work hard to get the job done. I agree with Bob that it's desireable to clean your fermenter between batches, although I'm sure thousands upon thousands of batches have been made without doing so.

Good luck!

Hmmm. Yesterday I over pitched because I want to get a quick turnaround on a stout kit. I pitched the packet of dry yeast, and I had another packet of dry yeast from another ale kit I made but used a liquid yeast instead.
Within 2 hours the thing was bubbling like mad, and was pretty warm (maybe that will help with some esters that I won't have from pitching properly).

I hoping because it is a stout that it won't matter too much. The time constraint is my biggest thing. We'll see.

norciabrewmonk said:

Hmmm. Yesterday I over pitched because I want to get a quick turnaround on a stout kit. I pitched the packet of dry yeast, and I had another packet of dry yeast from another ale kit I made but used a liquid yeast instead.
Within 2 hours the thing was bubbling like mad, and was pretty warm (maybe that will help with some esters that I won't have from pitching properly).

I hoping because it is a stout that it won't matter too much. The time constraint is my biggest thing. We'll see.

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How did that work out for you?

It still took about 3 weeks to completely ferment. The FG was still a few points higher than what the kit said it should be.

Not worth the extra packet of yeast, although since this was just a kit package, it really wasn't like I wasted it.
Probably can't expect much with kit beers anyway. I don't think I've ever had one attenuate to what the package said it would.

Still the beer turned out fine.

If overpitching leads to less esters and shorter lag times (is that right?)... what is the consequence of underpitching? More esters from the yeast? Longer lag times (if you don't use a starter)? Lower ABV in general? Or just a longer time in the primary before it reaches FG?

I'm curious because up till now I've been doing Mr Beer kits, which come with a mere 2grams of dry yeast. But from what I understand, the 5- and 6-gallon recipes call for 11.5 grams. That math doesnt work out, and Im curious of the consequence it had on my first few batches.

ps - Sorry to revive a 2-month-old thread. I was wondering about this today, and did a search rather than start a new thread.

My experience is that under pitching will accentuate the esters produced by a strain of yeast. I know I severely under pitched a Belgian liquid yeast and ended up with an in your face, over the top banana and clove flavor profile that time, allot of time, has not seen the lessening of those flavors. Since banana and clove are flavors this yeast gives of, the under pitching brought those flavors front and center.

Alright, I'm to late to go back band change this, but not to late to get an opinion. I racked my wort onto a cake from an IPA. The IPA was an OG of 1.082, the barley wine I just put in was 1.120 did I over pitch?

randmc said:

Alright, I'm to late to go back band change this, but not to late to get an opinion. I racked my wort onto a cake from an IPA. The IPA was an OG of 1.082, the barley wine I just put in was 1.120 did I over pitch?

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Hmmn, It is about how many healthy yeast cells you have. You started with a fairly "big" beer. Total guess - everything being equal - You'll be fine.

The previous batch didn't have anything that stressed the yeast, did it?