[flbrewer]

I have some general questions around over pitching;

-Will using more yeast than called for make for a longer fermentation period?
-At what point do you technically over pitch?
-Is it always bad, sometimes bad, who cares, if you over pitch?

[Jimmy K]

From what I've heard, it's hard to over pitch. You'd need to pitch a ton of yeast, like double or triple?. It would ferment quicker with more cells to do the work. Many of the yeast derived flavors (good ones) are created during the growth phase, when cells are multiplying. If you overpitch, you shorten the growth phase and reduce those flavors. This is probably more important in styles with dominant yeast flavors. There might be other effect too.

[flbrewer]

Interesting you mention double or triple....a few 1 gallon batches I've done instruct you to use half a pack of dry yeast (meant for a 5 gallon batch). In my mind, that would be enough yeast for a 2.5 gallon batch and I'm most likely using almost 3x more yeast.
Additionally, these one gallons are taking longer to ferment out fully and I've had some issues with acetaldehyde that I think may have to do with pulling off the yeast in 2 weeks vs. waiting longer.

[Jimmy K]

Huh, there may be more to this than I'm aware of. My info on overpitching is mostly hearsay.  Acetylaldehyde is caused by stress, so if overpitching stresses the yeast that's not surprising.

[Jeff M]

Interesting you mention double or triple....a few 1 gallon batches I've done instruct you to use half a pack of dry yeast (meant for a 5 gallon batch). In my mind, that would be enough yeast for a 2.5 gallon batch and I'm most likely using almost 3x more yeast.
Additionally, these one gallons are taking longer to ferment out fully and I've had some issues with acetaldehyde that I think may have to do with pulling off the yeast in 2 weeks vs. waiting longer.

a 5g batch of 1.048 Wort has a recommended pitch rate of 10grams of dry yeast assuming 90% viability.  if you are pitching half a pack of a 5 gram packet into 1g  then you are fine:)

Jeff

[klickitat jim]

Yes you can over pitch, pitch the correct amount for best results. However it's not as sensitive as some believe. If you need 350 billion cells and pitch 353 billion, no problem in my opinion. Pitching 700? Probably way too much.

From what I've read and heard and experienced, pitching too much can cause the yeast to go dormant too soon because they think there's not that much work to do. Well, they don't THINK, but that's the end result.

Personally,  I use a good pitch calculator and translate ml to cups, and I round off to nearest quarter cup

[majorvices]

YOu can often times get away with over pitching no problems. But you may leave the yeast weaker for the next harvest. Also, you may change the flavor of the beer some, it depends on the yeast, beer, and how much you have gone over. People often thing a short 4 hour lag is a great thing, but you actually want some lag. 12-24 hours lag is actually a good thing. If you are getting a 12 hour lag you are probably right in the zone, based on my experience.

Try to get close to pitching an appropriate pitch. You have some leeway up or down. IME it's often better to over pitch than underpitch, unless you are really going for stronger yeast flavors as in Belgians and Heverweizens.

[In The Sand]

Interesting you mention double or triple....a few 1 gallon batches I've done instruct you to use half a pack of dry yeast (meant for a 5 gallon batch). In my mind, that would be enough yeast for a 2.5 gallon batch and I'm most likely using almost 3x more yeast.
Additionally, these one gallons are taking longer to ferment out fully and I've had some issues with acetaldehyde that I think may have to do with pulling off the yeast in 2 weeks vs. waiting longer.

Use a yeast pitching calculator. I use mrmalty.com but there are others available. Then you'll see how difficult it is to over pitch (or even pitch the appropriate amount of yeast).  IME it's extremely hard to over pitch.

[reverseapachemaster]

I've heard the issues with overpitching are mostly related to losing yeast character in the beer. I seem to recall I've read something about the excess of yeast in the beginning can result in a big jump in temperature as fermentation kicks off and that can cause some high temperature-related fermentation problems.

[majorvices]

I've heard the issues with overpitching are mostly related to losing yeast character in the beer. I seem to recall I've read something about the excess of yeast in the beginning can result in a big jump in temperature as fermentation kicks off and that can cause some high temperature-related fermentation problems.

It can be that, but it also can cause major problems on the health of the yeast harvested. Kind of like putting too many sheep to graze on a small pasture. They end up not having enough nutrients and not replicating enough. The reverse, not enough sheep on a pasture, the replicate a lot but never replicate enough to consume all the grass. That's the way I've read Palmer describe it anyway.

[ynotbrusum]

I think that over pitching can result in excessive ester production in Addison to the other problems noted above.  The ester production results from an incomplete life cycle IIRC - can't find my Yeast book to confirm....

[Thirsty_Monk]

I've heard the issues with overpitching are mostly related to losing yeast character in the beer. I seem to recall I've read something about the excess of yeast in the beginning can result in a big jump in temperature as fermentation kicks off and that can cause some high temperature-related fermentation problems.

It can be that, but it also can cause major problems on the health of the yeast harvested. Kind of like putting too many sheep to graze on a small pasture. They end up not having enough nutrients and not replicating enough. The reverse, not enough sheep on a pasture, the replicate a lot but never replicate enough to consume all the grass. That's the way I've read Palmer describe it anyway.

Good explanation.

I would say that harvesting issue when over pitching is that you do not have enough growth and then you harvest old yeast.

[HoosierBrew]

I've heard the issues with overpitching are mostly related to losing yeast character in the beer. I seem to recall I've read something about the excess of yeast in the beginning can result in a big jump in temperature as fermentation kicks off and that can cause some high temperature-related fermentation problems.

It can be that, but it also can cause major problems on the health of the yeast harvested. Kind of like putting too many sheep to graze on a small pasture. They end up not having enough nutrients and not replicating enough. The reverse, not enough sheep on a pasture, the replicate a lot but never replicate enough to consume all the grass. That's the way I've read Palmer describe it anyway.

Good explanation.

I would say that harvesting issue when over pitching is that you do not have enough growth and then you harvest old yeast.

+1.  Really good analogy.

[euge]

I've heard the issues with overpitching are mostly related to losing yeast character in the beer. I seem to recall I've read something about the excess of yeast in the beginning can result in a big jump in temperature as fermentation kicks off and that can cause some high temperature-related fermentation problems.

It can be that, but it also can cause major problems on the health of the yeast harvested. Kind of like putting too many sheep to graze on a small pasture. They end up not having enough nutrients and not replicating enough. The reverse, not enough sheep on a pasture, the replicate a lot but never replicate enough to consume all the grass. That's the way I've read Palmer describe it anyway.

Good explanation.

I would say that harvesting issue when over pitching is that you do not have enough growth and then you harvest old yeast.

+1.  Really good analogy.

Plus 100.

You can certainly can run into dead yeast off flavors by over-pitching from a repitch. Poor performance from sick and scarred yeast and off flavors there too. I think it takes real discipline and timing. A conical to clean things up. Nothing I have.

[flbrewer]

Just bumping this because I went to Mr. Malty and entered in some information around a 1 gallon IPA. The necessary yeast from a standard 11.5g dry yeast pack is only .2! I've been pitching at least a half a packet on these one gallon batches.