How much yeast do you REALLY need?

[BrewnWKopperKat]

Over pitching is far better than under pitching for many reasons.

What would the pros/cons of over/under pitching be?

Also "truely" over-pitching on a home brew level is very difficult.

What amount of yeast would be a "truely" over/under pitched amount of yeast (assume a 5 gal batch)?

 

[fendersrule]

I expect people with more experience to answer most of your questions better. I've only made 30 batches but have used all types of yeast.

Under pitching is severely worse because longer lag time (more chance for infection) and more yeast stress leading to off-flavors. Over pitching on the home brew level (not in the "technical sense" but the "let me throw 2 packets in here instead of 1 packet" sense) = ZERO cons other than a few extra bucks in price. Over-pitching from a technical term (when you are REALLY over pitching which is HARD to do on a home-brew level) someone else can answer. Probably off flavors of sorts, but two packages of US-05 ain't going to do that. I don't even expect that three packets would either.

Be careful with some of the liquid yeasts. The little "packs" sometimes don't have the CFU count than a package of dry yeast would have (it still works fine as I found out, just a longer lag than what I'd like). Like always, read the instructions that come with your yeast. When picking up a packet of dry yeast, I am more confident that the yeast is good since it's frozen. With the liquid stuff, it seems more volatile to the environment, shipping, aging, etc. Neither are better compared to each-other. I buy what the recipe calls for.

Go to the manufacturer's website and do what they recommend. Other yeast calculators are making a lot of assumptions. I'd trust the manufacturer of the yeast more than anyone else. Some of them have OG calculators that tell you how much yeast to use. White lab prints an OG range right on their liquid packets. I do whatever that says.

 

[bleme]

I used 1 gram of dry Aurland #38. It took 22 hours to really get going, but made 5 gallons of fine beer...

 

[jgmillr1]

Dry wine yeast is typically pitched at a rate of 1g/gal and it's S. Cerevisiae like ale yeast. Proper rehydration is necessary as well as using yeast under 1 year old to avoid stuck fermentations. And these yeasts will ferment a 1.09 SG wine dry. So, I'm not seeing why the dose rate needs to be higher in beer.

 

[Qhrumphf]

Oh come on people, has anybody ever taken Biology? It's like a petri dish...any amount of yeast will do! It multiplies rapidly and soon becomes a huge colony! Even if you use just like 1/4 teaspoon, you're good to go.

Sat through a 20 minute random "biology" video on YouTube and am now a microbiologist. Took elementary school social studies and know everything about how government works.

Sit down before you hurt yourself.

Ultimately unless you're using a microscope and counting cells, it's all guesswork. Regardless, some strains/families (ie Kviek) do well with ridiculously low pitch rates. Most do not. Don't oversimplify it.

 

[Farside]

When I'm running multiple batches in a row, I'll pitch the entire yeast load from the previous batch into the new batch.

When I'm starting a batch with fresh yeast, I always start the yeast from a 5g packet for a period of time to grow it out. For a 5 gal batch it might be only 48 hours. for a 12 gallon batch it will be 3-5 days.

 

[BrewnWKopperKat]

I know anecdotes aren’t very useful either, but ...

... agreeing with (and perhaps building on) the anecdotes comment ...

I'm finding that anecdotes may lead to curiosity
which may lead to more casual observations
which may lead to controlled observations
which may lead to reproducible controlled observations
which may lead to more casual observations ...

I don't see how one can have "brewing science" without casual observation.

 

[SteveH aka shetc]

My personal experience is undoubtedly anecdotal as I am not collecting data of any sort. I do like the data collected by Brulosophy though it is mostly 1 off experiments. I switched to Imperial because of their success with that product.

For example, http://brulosophy.com/2019/03/28/ye...ter-in-an-amber-ale-the-bru-club-xbmt-series/

 

[mattdee1]

Under pitching is severely worse because longer lag time (more chance for infection) and more yeast stress leading to off-flavors.

^^ See, these are exactly the types of "established facts" that had me expecting that my batch of sorely under-pitched beer would end up sucking, yet, somehow, some way, it was completely fine.

The infection fighting benefits of a short lag time make a lot of sense intuitively, and for that reason alone I generally shoot for making starters with liquid yeast to shorten the lag time. But even there, I'm guessing that half-decent sanitation practices would more than buffer against a few extra hours of lag time. A lag time of over 24 hours certainly didn't matter in my recent experience.

As for under-pitching causing "yeast stress," this is one of those things that I have read a thousand times on forums and have just accepted as a real thing with real impacts on my beer because, well, it must be a real thing otherwise people wouldn't be talking about it all the time... right...?

Now, I'm not saying it's not a real thing; my concern is that the propensity for rote repetition of such nuggets of wisdom is out of proportion with the actual threat posed, which ultimately isn't very helpful to any of us. How many of us can:

1) claim to have direct experience with adverse effects in their beer that are directly attributable to "yeast stress due to under pitching." Surely it will be dependent on yeast strain, so for argument's sake, let's take a dirt-common yeast like WLP001 or US-05.

2) describe what the yeast stress effects actually do to the beer. Not theoretically using a bunch of esoteric biology jargon, but a real-world, qualitative description. If I have a basic beer like a blonde ale, which is light-tasting by design and will not be able to hide the markers of fermentation flaws, what will the markers of "yeast stress" taste like?

I'm genuinely curious here, not being a smart ass.

I have used those yeasts dozens of times, often in defiance of suggested pitching rates. Yet, it would be flat out deceptive of me to claim that I can speak on either of these points from direct personal experience.

 

[odie]

I did an RIS on a single dry packet of US-05. Very high OG. I ended up with 14%. One pack is all you probably will ever need on any beer.

 

[downzero]

I have never had a beer fail to ferment or have a stuck fermentation. I generally use dry yeast but my NEIPA I just made with liquid yeast and no starter (1.066) was done after 3-4 days. I fail to see the point of all this concern over pitch rates. I've had similar luck with repitched yeast.....what I get out of the fermentation is beer every time. I am thinking about making some starters in the near future just to see if the beer tastes any different, but I'm really having a hard time figuring out why. And as for commercial breweries pitching the equivalent of 3 vials, in that case, we're all massively underpitching and the calculators are all too modest. My yeast sure don't seem stressed, though.

 

[CascadesBrewer]

Interesting thread and interesting to see the wide advice and practices from experienced brewers. I do feel like yeast health and management are things that you need to play with and adopt a process that works for you.
My overall thoughts on yeast and fermentation is that:

1. It is one of the most important aspects of making great beer.
2. There are a dozen factors that impact this (pitch rate, yeast health, ferm temp, aeration, etc.)
3. If you do a few of them well, you can get by with lesser practices on the others.

For many years my general practice was to make a small starter (~24 oz, 600 ml) with a new pack (Wyeast/White Labs). I made the starter the evening before and pitched the entire active starter. I don't have a stir plate. I am coming back to the realization that this simple process might be my preferred method, even if the cell count growth is minimal.

I often do 2.5 gal batches and direct pitch a new pack. This is a good way for me to try out new yeasts and build up yeast for future batches.

These days I harvest yeast from my fermenter. I have had very good results direct pitching the slurry from either a 16 oz or 8 oz jar into a 5 gal batch. I like the idea of not messing with making a starter. I am still trying to figure out how much the age of the yeast impacts this.

I am starting to cycle back to making a starter with my harvested yeast by mixing up 24 oz of starter, and pitching the slurry from an 8 oz jar of yeast and then direct pitching the active starter into my batch. I am finding that I get faster starts and more vigorous fermentations. Even if the beer is not better, it is done a day or two earlier. It is always reassuring to see some signs of fermentation before going to bed on brew day. I did this for a 5 gal batch of a 1.118 Imperial Stout and I had excellent fermentation and attenuation (seems to taste okay...aging on oak cube now).

 

[Hoppy2bmerry]

@odie Perhaps, but just because you can, doesn’t mean you should ... off flavors. The variables with liquid... how was it handled before you got it? Was the correct temp held steady? Is it past its prime? A starter fixes that or won’t, but at least you know if you are pitching viable yeast.

 

[bleme]

at least you know if you are pitching viable yeast.

This is probably the most easily justified answer for me. I pitched dead yeast once. It sucked. I haven't bought liquid yeast since then, because I hate the bother of starters...

 

[mattdee1]

My overall thoughts on yeast and fermentation is that:

1. It is one of the most important aspects of making great beer.
2. There are a dozen factors that impact this (pitch rate, yeast health, ferm temp, aeration, etc.)
3. If you do a few of them well, you can get by with lesser practices on the others.

^^ this is a balanced take; I like it.

 

[Nanuk-O-Dah-Nort]

Technically you need "1"

and under optimum conditions, in one day, you'll have over 1Trillion

So...

But to make a specific taste/product, there are optimum amounts.

but it would seem other amounts work fine also.

 

[CascadesBrewer]

Technically you need "1" and under optimum conditions, in one day, you'll have over 1Trillion

So I am pretty sure that this idea is just false. I am not sure if 1 cell could grow to a trillion in one day but "optimum conditions" involve continuous stirring and aeration. That is good for yeast growth but makes terrible beer. In a standard wort there is just not enough oxygen and nutrients to support the number of generations of growth needed to get close to 1 trillion from 1. It would take 30 generations to get from 1 to around 1 billion, where pitching 2 billion cells only needs a few generations to get to 8 billion (which is a number I have read is what you end up with in a 5 gal batch with a decent pitch).

So maybe you don't need to pitch 2 billion (in a typical 5 gal 1.055 batch), maybe 1 billion works fine, maybe 500 million active yeast works well...but pitching 1 or 1,000,000 cells is bound to lead to issues.