Yeast amount

[Poppajim]

I'm brewing in small batches of two gallons. The yeast packs that come with the kits are about 5g and the ones that seem to be the most popular are 11.5g. I'm guessing these are for 5 gal batches. I'm not using those kits anymore, but plan on using 3.3 lb cans of Unhopped LME and adding hops and grains myself. Can I use the whole 11.5g or should I be using half and storing half? If I store the open pack, how should I keep it?

[BlackDuck]

When I started with Mr Beer and was doing 2.5 gallon batches, I always pitched the entire 11.5 gram pack of yeast. I would rather pitch a little too much than under pitch. You should be good using the whole thing. Once the yeast pack is open, it really should be used rather quickly, that's another reason I just pitched the whole thing, then I never had to worry about using old yeast.

[The_Professor]

...Once the yeast pack is open, it really should be used rather quickly...

I've heard the same as BlackDuck mentions. I have also read someone's post where they stated they used half packs and they were fine for a couple weeks.
I have also read that for wheat or Belgian beers it is best to limit the pitching rate since "stressing the yeast" will give them more of their characteristic flavors.

For anywhere between 2-3 gallon batches I usually just use the whole packet. Depending on the OG I might use less for a wheat or Belgian.

Higher OG requires more yeast, so a small batch with a high OG would actually need the whole packet.

I usually assume a lager needs double the yeast an ale does.

[mashani]

To be clear: 5g in 2.5 gallon batch is "enough". But 11.5g in many 2.5g batches is "better". The closer you get to commercial pitch rates the better for the most part. An 11.5g pack in 2-2.5 gallons is a great pitch rate for many types of beer assuming the yeast isn't brand spanking new (it rarely is), storage conditions, and depending on how many cells you explode when pitching, IE dry pitching vs. rehydrating and/or how good you are at rehydrating and/or your worts OG. If you pitch dry, then for sure I say to pitch the whole thing. I do this often. It's going to get you a good fermentation.

But that high of a pitch rate can eliminate banana esters and some other esters in some yeast strains, so if you want the banana, I'd pitch half a pack. That's the kind of thing Professor is talking about. Note that this is yeast strain dependent, and the dry strains are difficult to coax banana out of anyways. With liquid yeasts, Wyeast will SAY when this is a problem in their description. It's more of an issue for Wheat beers then Belgians IMHO, although it can apply to some Belgian strains depending on what exactly you want to coax out of them. It also depends on temperature, not just pitch rate. If you don't have experience with the yeast strain then in general I'd say always pitch a lot unless you know why you don't want to, or the manufacturer says differently.

Whether I pitch less or not is highly dependent on what I'm making and what yeast strain I'm using. RE: Belgians and dry yeast - a full 11.5g pack of Abbaye Belgian yeast is perfectly fine to pitch in anything IMHO, that high of a pitch rate seems to do it no harm, it still makes wonderful flavors. A full 11.5g pack of Bella Saison is also fine to pitch in anything. Those are actually the pitch rates recommended by Danstar (they recommend 2 packs for 5 gallons not 1) for those yeasts. For American/British beers, S-05, S-04, Nottingham, or Windsor in anything - the whole pack is great too.

[RickBeer]

I split the 11 - 11.5 g packs between two 2.5 LBKs, at the same time. They are designed for 5 gallons, not 2 or 3. I do this for S-04, S-05, Notty, Windsor...

[HerbMeowing]

Pitching the entire 11.5 gram sachet into a 2.5G of a garden-variety wort is not only a waste but it's a fookin'crime against nature.

The easiest way to split a dry yeast pack in two is to measure out two level teaspoons.

[Kealia]

Funny that this conversation is going down right now. I just pitched a whole packet of 04 in a MrB batch this morning. I rarely use dry yeast and even more rarely brew with MrB or BrewDemon so I had no reason to keep half around.

Sent from my Nexus 7 using Tapatalk

[mashani]

And I would argue there is nothing wrong with that. I do not consider it a "crime against nature".

Depending on the age of the yeast, storage conditions, and the number of cells lost due to dry pitching or rehydrating without everything being perfect, that pack of dry yeast might end up with only 50 (worst case) to 75% (more likely) viability from its theoretical cell count after pitching. (folks have demonstrated this messing around with their dry yeast, I'm not just making that up). Where a starter made from liquid yeast is to grow n# of truly viable cells before pitching. So as I said, 5g is "enough" but if you really want to be sure to only get the ideal 2-3 generations of growth and get it going rapidly without a lot of lag then the whole pack is not too much. Especially if you are fermenting with a ale yeast at cooler temperatures instead of at real ale temperatures (which is what lots of people do with S-05 for their IPAs, and even S-04 for their supposed English beers, because nobody in 'Merica likes "real ale" anymore, they want their yeast to be tasteless. So when they use S-04 at English temps they bitch that it has a flavor, so they ferment it in the low 60s to avoid such flavor... which although in spec according to packaging, is under spec in all reality, anything under 64 is a pretty chilly temp for S-04 really - so consider it as described above).

IMHO, any ale yeasts at the low end of their temp range should be treated like Kolsch/German ale (hybrid) yeasts. Hybrid yeasts are ale yeasts not lager yeasts. They just happen to be super clean fermented at the low end of their temp ranges. But they work best because of this like a lager yeast with a higher pitch rate. So instead of 5m cells/ml < 1.06, if you go by hybrid/lager rates, it should be more like 7.5 or 10m cells/ml at low temps. Also consider by yeast mfg. spec, often they say something along the lines of that 5m/cells ML at real ale temps is < 1.06, but at 1.06 they magically bump it to 10m cells/ML (and at 1.075 up to say 15m cells/ML). So you brew 1.03 beers, 5m is great... but at 1.056? Why would you argue 5m cells/ML is great for that too, but 10m is too much when at 1.06 suddenly 10m is what you need? (mfgs will tell you to bump all of those numbers up by 5m for lager yeasts too). There are of course more precise formulas for theoretical ideal cell count based on actual degrees plato/sg, Mr. Malty uses one of them. The one Mr. Malty uses is actually one of the ones that suggest less cells per ml. Some others would suggest more yeast cells per ml.

So anyways - is it *necessary*? No. But is it bad or wrong or a crime against nature? No. You by no means are seriously overpitching to the point of making beer that goes wrong if you pitch the full pack dry into 2.5 gallons, especially if you are fermenting on the cool side of an ale yeasts temperature range. Unless you are making a mild or standard bitter or a lower gravity pale ale then most 'Mericans make. Then maybe.

The only crime against nature is that a pitch rate that gives me only 2 generations of growth in the fermenter and signs of active fermentation in 4-6 hours after pitching causes in my house is that it makes my Brett sad. But unless I want Brett beer, that is a crime I can deal with.

Just for some comparison purposes, say you make a 800ML to 1L stir starter of a liquid strain for that 2.5 gallon batch - depending on wort nutrients available you end up with around 130-150 billion viable cells or there about if you do it right. I pitch starters of that size into 2.5 gallon batches all the time.

If you take dry yeast and figure 20 billion cells/gram (which is about where it tops out and not necessarily true of some newer strains that they have managed to coax into dry form), and then say 75% of it survives pitching/rehydration/storage/age, then your at around 170 billion cells from 11.5 grams.

Is that a super over pitch comparatively speaking that will cause bad things to happen? No way. Especially not at cool temps. And even at real ale temps, again, not unless you are brewing a mild or a bitter perhaps. Or a wheat where you want any banana. But you won't get banana of note with dry strains anyways, unless you push the yeast out of spec (IE 78 degree ferment for WB-06, even if you only pitch half a pack in 2.5 gallons).

[Poppajim]

Thanks everyone for the great information. I didn't expect so much. I learned more about yeast here than all the time I spent elsewhere. Thanks again.

[Pudge]

Great topic we've stumbled into. Yeast handling is almost as important as the recipe, can be done countless ways, and is often overlooked.

[BigPapaG]

Mash, you missed a zero...

I'm sure you meant 200 billion as opposed to 20 billion in paragraph seven...

[Beer-lord]

I believe in over pitching a bit, mostly with liquid yeast. I think the sooner they do their deed, the better.
And I routinely play with the temps to adjust the taste though that's a learning curve for me.
Mashani pretty much tells it all and agree.
We tend to take yeast for granted and every portion of our beer plays its part so we should try to keep them all happy so they work together.

[mashani]

Mash, you missed a zero...

I'm sure you meant 200 billion as opposed to 20 billion in paragraph seven...

I meant 20 billion cells per GRAM - that's going with Mr. Maltys magical numbers for dry yeast. So it's 200+ billion per 11 gram pack in theory. But it's not that much once you consider viability lost. The reality is that nobody really agrees with how much yeast is in a dry pack for real.

I've seen tested quantities with rehydrated packs of yeast (done properly) range from an effective viable yeast pitch rate of 8 or 9 billion per gram to 14 to 16 billion for per gram depending on yeast strain. Which I mentioned as the 50-75% viability if 20 billion is the magical theoretical amount. I don't think the testers could control for storage conditions before they got the yeast - it would have to be obtained outside of retail channels to really do that. But since we all get our yeast through retail, it's still valid information.

Manufactures sometimes actually only guarantee 5 or 6 billion per gram for some strains. Which makes sense to me as a number that they can always meet based on the results I mentioned.

My point is that even going with the magical Mr. Malty numbers, it's not a significant overpitch (if even an over pitch at all), and will not cause trouble, except in very specific low gravity or high ester beers if you consider the viability lost above. Remember that Mr. Malty is always considering it 20 billion viable cells per gram with only age as the loss factor. This isn't reality based on lots of peoples tests.

I don't know that anyone will ever agree about true cell count/viability for dry yeast, but it's not something you are going to screw up for the most part by pitching more unless you are getting ridiculous.

[BigPapaG]

Ahhh, mis-read on my part...

Good show!

[RickBeer]

Thanks everyone for the great information. I didn't expect so much. I learned more about yeast here than all the time I spent elsewhere. Thanks again.

When you ask questions like this, some people like Mashani share their extensive knowledge and give most of us more knowledge than we could have hoped for. One of the big advantages of this forum are the quality contributors like him, Screwy, and others (NOT Brewbirds or Joe Chiante though... )