Can you pitch too much yeast?

Is there an upper limit to the amount of yeast you can pitch? I had two mason jars with 1/2" of yeast on the bottom each. I pitched both into a 5 gal batch (1.049 OG) and fermentation took off. It is going really strong. Does too much yeast and to active a fermentation affect anything? How much is too much yeast in a 5 gal batch?

There's an interesting thread here, a big debate topic.

https://www.homebrewtalk.com/f163/why-not-pitch-your-yeast-cake-166221/


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WHAT DEBATE?????

Overpitching is easy to do.

Mostly, overpitching results in much faster fermentation, resulting in out of control temps.

Also yeast do not get to reproduce as much as they want to, they get bored, violent, canniballistic etc.

Yes you can over pitch. You need yeast reproduction, and the compounds produced during reproduction, to make a good beer. Over pitching removes this reproduction stage and leaves a beer thin and flat. I've personally properly, under, and over pitched and based on the results I'd rather under pitch than over any day. Depending on the density of your slurry you may not have been too far off. Check out mrmalty.com to get a better sense of proper pitching rates.

Ok....after reviewing MrMalty.com I believe I slightly over pitched my 1.050 og pale ale. Repitching from a slurry you should use 148ml (based off of my harvest date). This is just over 1/2 a cup and I probably pitched 3/4 of a cup. Fermentation was the most active I have ever had.

So I can expect a slightly thin beer. Flat? You must mean flat in some taste level. Co2 is regulated by the PSI.

A personal note to self - The WLP comment "Use 1 vial for 5 gal of beer...." is a BIG FAT LIE. It is way off. You need at least 2 and more if you do not use a starter and use them right away. Wow.......I need to start culturing my own yeast more often.

zaxsan said:

Wow.......I need to start culturing my own yeast more often.

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This was half the reason I got into yeast slanting. However the real reason was two stuck brews that I put down to dodgy yeast from LHBS. Having yeast that I have grown up from a slant I know exactly how viable it is and I have a pretty good idea (after doing a few) of quantity required to do the job. The cost.. is practically nothing. I save the hot break and hop material from the bottom of the brew kettle and strain out about 2-3qts of wort and can this with my pressure cooker it usually makes enough starter wort for the next batch of beer. If you read the sticky on slanting you will see all you need is some smaller containers (slants but I use baby food jars) a pressure cooker, agar, a blow torch and a loop of nichrome wire and you are in business.

Clem

Clem - silly question but when you use the slant do you just scrape off the yeast from the agar base or do you throw the lot into the starter wort?

I am a die hard yeast cake re-user.

I leave the yeast in my primary until I brew again.

I discard any excess (usually 3/4 of a cake) and leave the desired quantity. Pitch new wort, there you have it.

Got 19 batches from one packet of dry yeast.

cheezydemon3 said:

I am a die hard yeast cake re-user.

I leave the yeast in my primary until I brew again.

I discard any excess (usually 3/4 of a cake) and leave the desired quantity. Pitch new wort, there you have it.

Got 19 batches from one packet of dry yeast.

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Sounds sanitary. 19 batches, that's a tad more than is recommended.


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I am not so sure about pitching yeast 19 times.......I believe as you "reuse" yeast it can change the characteristics it offers to the beer. Perhaps a US-05 might not really change much, but any special strain would change over time. By no means am I saying this is a problem, but it would be hard to hit you style exact with a yeast cake used 19 times. (I also do not brew with the same yeast enough to even think about this)

After reading this thread and the others I believe I will start to wash my yeast and use it three times before starting with a fresh batch. And I will probably start making starters for my WLP and then storing them cool until I am ready to brew.

The deeper I get into homebrewing the more complex the system gets.......but the better my beer has become. I will starting pitching yeast better and see what becomes of it.

Thanks for the insight.

el_caro said:

Clem - silly question but when you use the slant do you just scrape off the yeast from the agar base or do you throw the lot into the starter wort?

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Not a silly question at all, I mucked around with some slants for a while but trying to get the wort into the slant was messy at best. I did not want to use a funnel as it was yet another source of infection and those early stages of yeast propagation are the critical ones for sanitation.

So my solution is with slants I scrape as much off with a nichrome loop into a 10ml wort solution in a test tube then to a 50ml of wort in a baby food jar but I prefer to use baby food jars with agar on them. This way I pour about 50ml into a slanted baby food jar, there is an excellent amount of surface area in the jar for the yeast to grow on and so I have a very quick initial ferment off the "Slant". I then pour this into a 250ml flask with about 150ml of wort and put it on the stir plate. This steps starts my crash cool, decant, swirl and pitch into the next starter routine. I then step 500ml to 1L -2L(depending on what is required). I leave this in the fridge until I'm ready to brew then morning of the brew I decant. swirl and pitch into a stater around the same size as the last step just to wake them up and get them in a eating kind of mood, I then pitch this whole starter so I don't stir this one as I don't want it too oxidized.

To figure out my yeast cell number I use around 180 million yeast cells per ml (this number came from Maltose Falcon website on yeast propagation and maintenance; good read!) when mixed on a stir plate so a 1L is around 180 Billion Yeast cells.

Clem

I think you can over pitch. I think it's a very difficult thing to do however and don't believe exceeding MrMalty's starter size by a liter or two is going to get you the negatives described in this thread. I'm no scientist, that just comes from experience with a stir plate and making starters for every beer...