Pitching Rate Tolerance

[3 Dawg Night]

I've brewed a few 1-gallon batches, and I'm planning to move up to 3-gallon batches soon. As a small (i.e., less than 5-gallon) batch brewer, and a new brewer in general, I'm having trouble figuring out how close I ought to try to be to my calculated pitching rate. Obviously, if I'm under the calculated pitch rate, I should make a starter, but what if I'm slightly over the calculated pitch rate?

An example:
I'm getting ready to brew a 3-gallon American Pale Ale using SafAle US-05. The Brewer's Friend yeast calculator tells me that a packet has 110B cells available, and that the target pitch rate is 75B cells. Is that close enough? Should I pitch the entire packet, or should I try to weigh out 3/4 of the packet?

 

[Immocles]

I brew 2.5G-4G batches mostly. If I'm pitching a new pack of yeast, I use an entire packet (smack pack/white labs/dry). I'll occasionally pitch a packet of us05 with a bit over half (because I also brew 1G batches on occasion and only use a third of a packet) and not think twice about either way.

 

[VikeMan]

I'm getting ready to brew a 3-gallon American Pale Ale using SafAle US-05. The Brewer's Friend yeast calculator tells me that a packet has 110B cells available, and that the target pitch rate is 75B cells. Is that close enough? Should I pitch the entire packet, or should I try to weigh out 3/4 of the packet?

In general, an overpitch is less problematic than an underpitch. That said, I would have no problem pitching less than a full pack, if that's what my target rate called for.

ETA: I think some people see pitching less than a full pack as "wasteful" if the rest of the pack doesn't get used. But if it doesn't make more beer, or make better beer, how is it wasteful?

 

[brewbama]

The mfr recommends 50-80 g/hl for -05. So, that’s .5-.8 grams per liter. 3 gal = 11.4 liters. Therefore 5.7 - 9.1 grams. I’d meet it middle of the road and pitch 7 grams.

 

[VikeMan]

View attachment 676937

The mfr recommends 50-80 g/hl for -05. So, that’s .5-.8 grams per liter. 3 gal = 11.4 liters. Therefore 5.7 - 9.1 grams. I’d meet it middle of the road and pitch 7 grams.

They quote a pitch rate that ignores wort gravity? Why not, I guess. That's not much worse than the directions the big two liquid yeast manufacturers provide.

 

[brewbama]

I suppose that’s where the variance of .5- .8 comes in. Low end for low octane and high end for high octane.

Lallemand (a dry yeast competitor) uses wort gravity as a variable in their calculator. If you were using BRY-97 (a different West Coast Ale yeast), the result would be based on gravity and volume.

 

[ike8228]

What happens if he over pitches? I’ve been wondering that myself. Is there such a thing? What if you make a starter and it becomes ‘too big’? How do you know/measure a starter (how many cells are in it).

 

[RM-MN]

There is very little differences in a slightly under pitched or slightly over pitched beer. You have to get pretty far off the ideal to be noticeable. The ideal pitch is primarily for a big brewer who needs the fermentation to start quickly before any bacterial infection can get started and needs the fermentation to be over as quickly as reasonable to be able to empty the fermenter and start a new batch. I would presume that getting a second fermenter would not be a financial hardship for most homebrewers.

 

[VikeMan]

What happens if he over pitches?

The main consequence of over pitching is a bland beer, with reduces esters, i.e. "too" clean.

Is there such a thing?

Yes. But I'll add that the term "over pitching" is subjective, because we're all free to choose the pitch rate we want for any given beer. So "over pitching" would be IRT that choice, not necessarily some standard. As an example, I pitch my Imperial Stouts at lager-like rates or even higher, intentionally discouraging esters.

What if you make a starter and it becomes ‘too big’?

I'm not sure what you mean by "becomes" too big. The way to build a starter is to decide on the desired pitch rate, estimate the number of cells you're starting with (using # of packs and age), and put that data, along with your starter method (e.g. shaken or stirplate) into a yeast calculator. It will tell you how big a starter to make.

How do you know/measure a starter (how many cells are in it).

You'll never know for sure, unless you count cells with a microscope. But the cool thing about yeast starter cell growth is that if you (or the calculator) underestimated or overestimated your starting cell count, the change in output is not linear. For example, if you started with only half the cells you thought you had, the post-starter cell count will be more than half of the amount you were aiming for. And if you somehow started with twice the cells you thought you had, the post-starter cell count will be less than double the amount you were aiming for. So even though you (or more likely a calculator) have to estimate the starting cell count, the nature of the growth curves makes the post-starter cell count somewhat self correcting.

 

[VikeMan]

The ideal pitch is primarily for a big brewer who needs the fermentation to start quickly before any bacterial infection can get started and needs the fermentation to be over as quickly as reasonable to be able to empty the fermenter and start a new batch.

I'll just add that having yeast stay ahead of bacteria should be just as much a concern for homebrewers. Not (necessarily) for financial reasons, but for quality.

I'll also add that with proper sanitation, an under pitch shouldn't be of much concern (strictly from an infection standpoint) for either type of brewer. But there are other reasons not to do it.

 

[3 Dawg Night]

There is very little differences in a slightly under pitched or slightly over pitched beer. You have to get pretty far off the ideal to be noticeable.

That's really the crux of my question. is 1M cells "slightly" under/over? Is 10M? 100M? 1B?

 

[madscientist451]

Using the whole pack isn't going to hurt anything. When its done, save the yeast slurry in a jar and use about half of that in the next batch.
If you are making a beer like a heffeweizen and are looking for a specific clove/banana flavor ratio then your pitch rate is more important.
But in regular ales and lagers, more yeast is usually better than not enough.