overpitching?

[jgress]

Can you overpitch yeast? Like I've heard of the risk of underpitching, or of killing of too many yeast cells by e.g. pitching dry yeast without rehydrating first. But are there risks with pitching too much? I'm making a gallon batch of Kolsch, and I got a vial of White Labs Kolsch liquid yeast. Pitching just half won't work since the liquid yeast doesn't last long after opening, so should I just pour the whole thing in?

 

[kombat]

You can overpitch, but in my opinion it's far less of an issue than underpitching. In your case, I'd pitch the whole vial into the batch.

 

[MaxStout]

I've been told that over-pitching can cause off-flavors. But that has to be WAY overpitched, like a couple times or more than what's needed.

If you have the available fermenters, why not make a couple more 1-gallon batches and split the yeast? You can use this calculator to determine the proper pitch rate. Plug in numbers and see how many gallons you can pitch with the vial.

 

[flars]

You can also make a large starter with the vial of yeast. Pitch what you need and save the remainder. You will have fresh yeast, that has not fermented a beer, to use for your next brews.

Harvesting yeast from the primary will also build your stock of yeast for future brewing.

 

[billl]

"Pitching just half won't work since the liquid yeast doesn't last long after opening, so should I just pour the whole thing in?"

Not sure who told you that. The yeast don't really care if you open the lid as long as you don't let contaminates in. Lots of brewers save yeast in mason jars etc from batch to batch with no issues.

 

[Cyclman]

Save the yeast, use it as a starter for your next beer. Overpitching can cause less flavor, as ester flavors come from the yeast propagating (why Belgians often intentionally underpitch). Obviously, a lot depends on the style you're doing, an IPA it would matter much less than a dubbel.

 

[vNmd]

I've been told that over-pitching can cause off-flavors. But that has to be WAY overpitched, like a couple times or more than what's needed.

If you have the available fermenters, why not make a couple more 1-gallon batches and split the yeast? You can use this calculator to determine the proper pitch rate. Plug in numbers and see how many gallons you can pitch with the vial.

I use the new yeast calc site every time and have noticed the difference in the two stir plate aeration values are not really close to each other (306 vs 377 billion total cells for example). I have also heard over pitching by a lot is bad. I usually guesstimate the average of the two different values, but since there is a 20ish percent difference in the aeration values - is 20ish percent enough to be concerned about over pitching if the lower value is more accurate? Does anyone know if one of those values is more accurate than the other when calculating total cells?

 

[MaxStout]

I use the new yeast calc site every time and have noticed the difference in the two stir plate aeration values are not really close to each other (306 vs 377 billion total cells for example). I have also heard over pitching by a lot is bad. I usually guesstimate the average of the two different values, but since there is a 20ish percent difference in the aeration values - is 20ish percent enough to be concerned about over pitching if the lower value is more accurate? Does anyone know if one of those values is more accurate than the other when calculating total cells?

There was a thread that kicked around the different stirplate calc methods. I can't recall if there was a consensus; you can check out the thread and draw your own conclusions. I used the more conservative formula on Yeastcalc.

I don't think overshooting pitch rate by 20% will be bad. There are so many variables in yeast handling and the prep of starters, that 20% becomes sort of negligible anyway. I think you start to have problems when you double or triple the rate.