Overpitching

[The Bone2]

Seems like underpitching is a potential problem. Make a starter, increase the cell count, blah blah.

What is the impact of "overpitching"? What if you used (2) vials of yeast instead of just one?

What if you made your starter with (2) vials of yeast instead of just one?

No underpitching, right?

 

[SuperiorBrew]

Is overpitching yeast harmful?

If the beer is overpitched, yeast do not grow though a complete growth cycle. This results in few new yeast cells, which makes for unhealthy yeast and low viability by the end of fermentation.

I always use the calculator on MrMalty.com

 

[DeathBrewer]

it is very difficult to overpitch. unless you pitch like 5 packs of dry yeast, you will be fine.

2 vials in one batch is a fine amount of yeast for any batch (except possibly very large beers.) 2 vials in a starter would be fine (but probably unnecessary...just step up your starter a few times and save some money)

EDIT: but yes, check out good ole mr. malty's calculator:

http://www.mrmalty.com/calc/calc.html

 

[gruntingfrog]

Additionally, in beers that benefit from esters and phenols which are caused by yeast reproduction, overpitching will keep these from being produced resulting in a lackluster beer. For example, an overpitched hefeweizen would be quite boring indeed.

 

[DeathBrewer]

yes, but 2 vials for a 5 gallon hefe would not be overpitching

 

[gruntingfrog]

Definitely not.

 

[david_42]

Many of us pitch on the cake occasionally. That's about the only time a home brewer might get close to over-pitching and I've never seen a problem doing it.

 

[Funkenjaeger]

You've got to remember that even when homebrewers make starters and all that, we're almost always STILL underpitching, by commercial brewers' standards anyway. Most of us could probably safely double (if not triple, quadruple, or more) the size of our typical starter and still be perfectly fine, but making gigantic starters is more expensive, and not necessary enough to bother with unless you're dealing with a huge beer where you need all the yeast you can get.

From the White Labs FAQ:

An often quoted number is to pitch 1 million cells/ml/degree Plato of beer, which equals about 250 billion cells for 5 gallons. That is okay, more cells are not detrimental until about 400 billion cells.

400 billion cells is a lot. You'd probably need to pitch at LEAST four liquid yeast packs/vials, assuming they were totally fresh, or way more of them if they were a month or more old. Even with dry yeast, you'd likely need 3-4 packs, and that's assuming they're in good shape and you rehydrate for maximum viability.

As david_42 says, pitching on a yeast cake seems to be the only likely way for a homebrewer to overpitch. If you put a big beer on a smaller beer's yeast cake I think you're almost certainly fine. If you were trying to use a yeast cake from a bigger beer on an identical (or smaller) beer, you may want to start thinking about removing some of the yeast cake, but I don't think that's a huge concern, especially if you wash your yeast cake, which involves the loss of some of the yeast anyway.

 

[TheBone]

If overpitching is rarely a problem,
but underpitching is a common problem,
and using two vials of yeast is not a problem,

then...

The only reason not to pitch two vials of yeast would be the cost? ($5-8 per 5 gallons?).

That seems like a small price to pay for improved beer.

 

[zoebisch01]

If overpitching is rarely a problem,
but underpitching is a common problem,
and using two vials of yeast is not a problem,

then...

The only reason not to pitch two vials of yeast would be the cost? ($5-8 per 5 gallons?).

That seems like a small price to pay for improved beer.

True, it is a logical conclusion....but....you can make fantastic beer on standard amounts. There is really no need to do so. If you want to pitch 2 vials, you are better off making a starter to increase your cell count as most people do.

I personally would not put the money of 2 vials into a 5 gallon batch. In fact my batches are closer to 6 gallons and I get great results....and.....I have always direct pitched my packs. I have racked onto a cake for a high gravity batch, in fact that is my methodology rather than making starters. If I want to brew high gravity I do a primary brew with the yeast I want for the high gravity and then take advantage of the process.

Underpitching I think isn't nearly as much of a common problem but rather lack of aeration, temperature and general initial health of the yeast are.

 

[cheezydemon]

Save your yeast. When your batch is done and kegged or bottled. Pour half of the yeast cake into a sanitized jar and refridgerate.
Pitch on the leftover cake.

 

[Scimmia]

If overpitching is rarely a problem,
but underpitching is a common problem,
and using two vials of yeast is not a problem,

then...

The only reason not to pitch two vials of yeast would be the cost? ($5-8 per 5 gallons?).

That seems like a small price to pay for improved beer.

Which is why almost everyone here recommends a starter. A 2 liter starter (non stirplate) will about double the cells in a "pitchable" tube/pack from ~100 billion to ~200 billion, for a fraction of the cost of another tube.