Dry Yeast Pitch Rate and Bulk Dry Yeast

I started recently using dry yeast, and I know there is a ton of info on dry yeast in this and other forums, and I have been poking around what I could find readily in an effort to simplify my use of dry yeast, and pin down some expectations regarding pitch rates, attenuation, temperatures, esters and other flavor components, etc. Also new to me is the notion I can buy dry yeast in bulk which should give me the ability to better control my pitch rates while minimizing waste and lowering cost.

Right now I’m really not that worried about spending another $4 on a second packet of US-05 to ensure my fermentation is healthy, but I feel as though, since I’ve moved to using dry yeast, I’ve gotten away from more accurately controlling pitch rates and have to wonder; is my beer as good as it could be if I am not being that particular about pitch rates? I control just about every other variable to the Nth degree in my process, but this one variable has sort of gone by the wayside.

That said, this begs a couple of questions: 1) Assuming one is using a reliable yeast calculator, how much of a tolerance is acceptable for a calculated pitch as expressed in cell count? 2) Does dry yeast respond differently than liquid yeast with regard to growth rate? In other words; would 306B cells of dry yeast pitched directly into the wort result in the same fermentation (same growth rate, same final cell count, etc.) as 306B cells of slurry propagated from a package of liquid yeast?

Example: I calculate 306B cells required for 6.5 gallons of 1.068 SG wort. Now, I take a certain amount of a dry yeast and, assuming, say, 6B cells/gram I calculate how many grams needed to get to my 306B cells (51g), weigh it out from my bulk container and pitch accordingly.

If pitching 306B cells of slurry from a starter made with liquid yeast I feel pretty confident I’m getting a good healthy pitch. But for some reason I feel like pitching 4.6 packets of dry yeast for a 1.068 wort is overkill. The Lallemand site tells me I need 5 packets – they also say I need 521.63B cells! Something seems fishy here.

My goal is to buy dry yeast in bulk and store it cold like I do for my bread yeast and weigh it out as needed based on cell count required for a given SG and volume. But I want to be sure I’m using the correct amount of dry yeast and not going overkill.

 

I use 1 gram per liter for no other reason than I heard a Fermentis presentation from the AHA convention say that was recommended. However, they were discussing 34/70 I just use the rate for all dry yeasts.

 

Hey, that's just their claim. People previously calculated the amount of yeast cells in Fermentis packs and they figured it had more than 200B cells per pack. That puts it at >17B per gram. It makes sense they are going to use the "safe" number, a minimum guarantee. Not to mention most people will splurge it directly to the wort, killing most of them(but still leaving them with a sufficient amount)
They also had an expiration date of 1 year up until recently when they bumped it, except dry yeast clearly lasts way more than that. They just used the numbers they can guarantee.
Fermentis packs say one pack of yeast should be good up to ~8 gal, so I trust that number to be safe.

 

The brewersfriend calculator might be more useful for what you are trying to do. Buying in bulk, if you are going to brew regularly and will use it up over let's say 5 years, seems like a good way to go, but keep in mind that over time, your interests change and you may branch out and abandon that particular yeast altogether. Perhaps even quit brewing (God forbid!). I can say that I also made my own bread for years and had a large package of instant dry yeast in my freezer for something like 7 years and it always made good bread. It was long expired and I continued to use it with no problem.
Not sure why they put such a short time period (about 2 years is what I've seen) on the brewing yeast packages, maybe they don't last as long? Seems like they would be using the same technique for making the yeast.

 

I've seen estimates up to 18B/g which, if even somewhat accurate, it sounds as though one could average anywhere between 10-15B/g in an average packet of dry yeast, depending on yeast type, I would assume. So even if I assumed 150B viable cells per 11g packet of, say, US-05, that would mean that if I pitched just one packet in my 6.5 gallon batch of 1.068 wort, I'd be grossly underpitching, yes? My last couple of IPAs clocked in at 1.068 and I did get 6.5 gallons into the fermentor and I did pitch two packets of US-05, and even though it did take greater than 12 hours before any activity was noticed (I used to get about a 6- to 8-hour lag when using a starter with liquid yeast), it seems each batch fermented out just fine.

I'm sure I read an article recently in one of the brewing mags - from Fermentis, I think - indicating that the "pitch directly into the wort kills half the viable cells" thing was just a myth now that the processing techniques have gotten so much better. I think there may also be a Brulosophy write up on this topic indicating little to no difference in performance between dry yeast that was rehydrated vs. dry yeast that was just tossed directly into the wort. I apologize for the lack of credible references - I'm sure I could dig them up if I took the time.

The question still remains; does dry yeast act differently during the first 8-12 hours after pitching than the same cell count of liquid yeast?

 

caution: not related to question that remains (see above).

When experts disagree (as they did in in the early 2010s with dry yeast)

• The book "Yeast" (published fall 2013), p 124, has a similar statement on the "kill rate" when pitching directly.
  
• The "way back machine" has Fermentis product information sheets (S-04 was one of them) from the early 2010s which offer direct pitching of dry yeast as an option (for example, https://web.archive.org/web/20110812160409/http://www.fermentis.com/fo/pdf/HB/EN/Safale_US-05_HB.pdf)

there is a way forward

edit: added archive.org link

 

Interesting note in the archived Fermentis sheet;

Could explain why my lag times are longer now - I have been sprinkling the dry yeast directly into my conical while filling from the bottom - who knows if it clumped, I never checked. I also normally pitch right around 65 F so this is below their recommended dry-pitch temperature. Next time I will rehydrate and see if this affects my lag time. I may also try pitching at a higher temperature and slowly dropping to my desired fermentation temp over a 6-8 hour period (or so).

 

I recently found new information on the Fermentis website - for both dry pitching and rehydration: https://fermentis.com/wp-content/uploads/2019/10/Brochure_Tips_and_Tricks_BAT_BD.pdf
The 68 degree reco for dry pitching is gone. I plan to dry pitch on my next batch. For rehydration, the hydration media temperature is now 50 - 82.4F, and ideally shoud be close to fermentation temperature. This is much lower than the previous reco.

 

Dried yeast is extremely viable, much much better than most "experts" will proclaim. One single pack of dried yeast, even without rehydrating, is PLENTY for 6.5 gallons of 1.068 ale wort. Based on dozens upon dozens of batches of experience, I haven't had any problems with the following basic assumptions:

With DRIED yeast, I split my packs. 1/2 pack good for 5 gallons of ale, or approximately 1/8 pack per gallon. Or 1 pack good for 5 gallons of lager, and 1/4 per gallon.

For LIQUID yeast... of course you should always use the entire pack, and make a starter for anything more than say 3 gallons unless it's super-duper fresh just manufactured in the last couple weeks.

See also this thing, read it in its entirety, especially the last 3 or 4 pages:

https://www.homebrewersassociation.org/forum/index.php?topic=27438.0

 

I agree that pitching rehydrated vs. dry makes no difference, but that's just about how much yeast is in each pack as well. At 250B cells per pack, even if only 100B survived, that's still more than sufficient for the vast majority of homebrewers since we rarely if ever go above 8 gal batches, and most people brew ales which have way more leeway than lagers. The comfortable range is way more than most people think. To overpitch or see a difference in the end result, you need to use an almost equal wort-to-yeast ratio. To underpitch, you have to throw away most of the pack.
I don't think the "pitching directly kills half the cells" thing is a myth, the science behind it checks out for me. If someone working in this field or a microbiologist shows me a paper or an experimental data indicating otherwise, I am more than happy to change my beliefs.
I have previously pitched to an entire yeast cake, and just 1/4 of the yeast cake. No real difference, except in the lag time. It's way easier to underpitch than it is to overpitching, but even that's hard to do unless you are acting careless.

This is what I do as well. I save the other half for another batch or keep it in the fridge after sealing it back and placing it a near-vacuum bag. I do this just to have some yeast if my fermentation gets stuck or doesn't work out for some reason, though I never had to resort to using the other half so far. Previously I just had some yeast stored in beer bottles, but just saving some of the pack I can then multiply in a starter in case something goes wrong is just easier.

I don't think so, the pack itself suggests a single pack for up to 8gal straight into the wort, and 1.068 isn't so high as to be a stressful environment for the yeast, though it's the start of the upper-end. I could see the underpitching argument above 1.08(or simply a larger batch), though.
I think most people can agree the estimates and suggestions of yeast producers are going to be on the safe side, since they want to sell you more yeast and make sure their yeast actually works. As long as you are in the suggested range and the gravity isn't so high, I'd say that's far from underpitching let alone an obvious case of it.

 

All great information, and my questions have been adequately addressed. Thanks guys for all the input - much appreciated. This is exactly why I like this forum!

 

When I wrote reply #6, I didn't make time to track down this link (posted a couple of years ago) - it was written a well before the Fermentis E2U announcement.

 

Thanks for the link!

Previous versions of this document have been good. This one also looks like a great "point in time" resource for those who brew with dry yeast.

It's good to see the brochure reinforce that one can either pitch dry or rehydrate (page 20)

Also, there's a Q&A page at https://fermentis.com/en/tips-n-tricks/questions-and-answers/

 

.5 - .8 grams per liter for ale, .8 - 1.2 grams per liter for lager. I round to 1 gram per liter for both.

 

I planned on buying Safale US-05 in bulk and getting more exact about pitching rates, especially as I was considering going up to 6.5 gallons batches where I'd ferment 4.5 gallons in a keg and 2 gallons in a small fermenter for bottling. It's harder to use packets for that split.

But then I decided to just stick with 4.5-5 gallons in a keg, and use one packet. A lot of people think that's underpitching. But I feel like 1 packet in 5-5.5 gallons is (by far) the most common pitching rate in homebrewer circles, and our beer comes out good. If we were severely underpitching, wouldn't most of us have consistent off flavors? And if one packet wasn't enough for a normal-strength beer, wouldn't the yeast companies just come out with a packet that's better suited for the most common brewing rates (~5 gallons, ~5% ABV), such as 14 grams instead of 11.5 grams?

I get my yeast for great prices at Label Peelers. At around $2.50/packet, and the convenience of just cutting open the packet and sprinkling it onto the wort, it just made more sense for me to stick with packets.

 

Thanks - I hadn't found that before. I noticed that it shows the higher temperature range (25 - 29C) for rehydration of ale yeast, while the Tips and Tricks brochure shows 10 - 28C. I emailed Fermentis and asked about it and will post what I find.

 

Good point - I'd think the homebrewing community would be large enough to elicit a change in the packet size for dry yeast if needed; I have to assume that the 11.5g packet size was developed specifically for homebrewers. If no such change is being asked for, the masses must be getting acceptable results pitching one packet into an average 5-6 gallon batch of ale.

Aw crud; this begs yet another question - why 11.5 grams? How'd they come up with THAT number?

 

Seems fair to "cross-check" their material.

and perhaps another: why does it vary by yeast lab? My most recent package of Nottingham was an 11 gram package. My most recent M44 package was a 10 gram package.

 

Well, Mangrove Jack probably loses 1-1.5 grams when they repackage the yeast from the other manufacturers. ;D

 

Fermentis answered:
"Thank you for contacting Fermentis. All our strains can be direct pitch into the wort, as long as the wort is between 10 to 28°C. That will not affect the yeast viability, vitality and resulting beer. If you want to rehydrate the yeast, also do it between those temperatures.

This is the latest information we have on our strains based on the latest trials. I apologize that there still is some potential confusing information in our written documentation."

Apparently the FAQ section still has some old info, and 10 - 28C is the optimum range when either direct pitching or rehydrating.

 

Anything Fermentis: 1 sachet for 5 gallons up to ~1.065.
Anything Lallemand: 1 sachet for 5 gallons up to ~1.060. I have a feeling Lallemand packs less cells than Fermentis.

This was my experience in the past 3 years with around 90 batches brewed to date.

However, lately, I have been adding more yeast. I have not noticed a difference between new and old batches in terms of fermentation, aroma, flavour, etc.

 

After Fermentis answered my rehydration temperature question, I went on to ask about dry pitching on foam. My question: "I'm planning on pitching direct (dry) for my next batch. But I use top-off water, which I stir in before pitching. (In order to get 65F overall pitching temperature, the top-off water can be much colder or warmer than the wort from the kettle, depending on the season.) This prevents me from exactly following the instructions in the Tips and Tricks section: "To do so we recommend using the necessary quantity in weight of ADY and to put it into the fermentation vessel during the first part of the wort cooling step." The surface is very foamy. I'm concerned about sprinkling the yeast on the foam and leaving it, and my concern about contamination prevents me from waiting 10 minutes before stirring. I think gently stirring the yeast into the wort immediately after pitching would approximate the results that the instructions call for. Would this be correct?"

I got this answer:
"Direct pitching is the method with the lower chances of contamination as there is no yeast handling prior pitching. But, in your case, with the presence of foam on the surface of the liquid is for sure not ideal. Sprinkling the yeast on the foam will leave some yeast outside of the liquid which is no good. I will definitely rehydrate the yeast with water or wort in a sanitized container and pitch that slurry. If you stir, remember that is has to be gentle, max 100rpm on a stir plate or equivalent. Agitation (over 100rpm) during rehydration is the main cause of loss of viability in the yeast."

 

Here’s how I pitch dry yeast:

 

Any chance that you will put some/most/all of your Q&A with them into a single post that can be referenced in the future?

 

Not sure if this was addressed, if you buy Fermentis in the bulk package, you’d need to use it all within 7 days according to the rep who spoke at nano-con

 

Any chance that you can put some/most/all of what you learned at nano-con into single post that can be referenced in the future?

 

Any chance that you will put some/most/all of your Q&A with @BrewnWKopperKat into a single post that can be referenced in the future?

 

From what I remember...

No need to rehydrate

Use two packs when OG is over 1.060

Can pitch directly into wort and not lose half the cells

Once a pack is opened must be used within a few days

And dry yeast can be reused up to 5 times before tossing

 

I wonder; why? This would make useless my initial idea of buying dry yeast in 500g bags. I suppose I could by the sachets in bulk...

Hey, wait a minute... now that I think about it; I've been using the same batch of dry yeast for bread making for over 3 years - it just sits in an airtight container in my freezer - and those loaves come out just fine. Couldn't the same apply for US-05 or any other strains of brewer's yeast?

 

I buy jars of active dry yeast that I keep in the fridge for bread baking. Not sure why the same can’t be done for other dry yeast.

 

When I was considering bulk dry yeast, I saw plenty of people that vacuum sealed it and put it in the freezer. I don't think that should be an issue.

 

I've been head scratching over the "use in 7 days" bit too. I likewise buy bricks for baking and just keep it in a Mason jar in the fridge with no issues. I wondered if the concern (especially for commercial brewers) was the possibility of contamination once open, but can't see how a week or a minute presents a different risk if there's a risk at all. Maybe they just want you to throw it out so you'll throw another couple Benjamins at them sooner.

And as for repitching 5 times... dry yeast is no different than liquid yeast in this respect. Once pitched, it is a liquid culture. There is no number of generations you can go that is set in stone. You might go dozens of generations, or indefinitely, or only one or two. It's mainly dependent on the yeast and the conditions it experiences (oxygen, nutrients, alcohol, handling and storage....) If you like the job it's doing, reuse it. As soon as you're dissatisfied, replace it.

 

By popular demand, here is the info I got from Fermentis:

1-11-20 ME: Your FAQ page answers the question "I see the recommended rehydrate temp for ale yeast is 25~29°C? My pitching temp for ale is 18°C. Will this not "stun" the yeast?". The Tricks and Tips page states "The temperature of the hydration media is between 10 and 28°C (50-82,4°F); and should ideally be close to fermentation temperature." This is lower temperature than the previous recommendation, and lower than shown on the FAQ page. It the lower temperature range a new recommendation?

1-13-20 FERMENTIS: Thank you for contacting Fermentis. All our strains can be direct pitch into the wort, as long as the wort is between 10 to 28°C. That will not affect the yeast viability, vitality and resulting beer. If you want to rehydrate the yeast, also do it between those temperatures.

This is the latest information we have on our strains based on the latest trials. I apologize that there still is some potential confusing information in our written documentation.

1-14-20 ME: Thanks for the explanation.

I'm planning on pitching direct (dry) for my next batch. But I use top-off water, which I stir in before pitching. (In order to get 65F overall pitching temperature, the top-off water can be much colder or warmer than the wort from the kettle, depending on the season.) This prevents me from exactly following the instructions in the Tips and Tricks section: "To do so we recommend using the necessary quantity in weight of ADY and to put it into the fermentation vessel during the first part of the wort cooling step." The surface is very foamy. I'm concerned about sprinkling the yeast on the foam and leaving it, and my concern about contamination prevents me from waiting 10 minutes before stirring. I think gently stirring the yeast into the wort immediately after pitching would approximate the results that the instructions call for. Would this be correct?

1-14-20 FERMENTIS: Direct pitching is the method with the lower chances of contamination as there is no yeast handling prior pitching. But, in your case, with the presence of foam on the surface of the liquid is for sure not ideal. Sprinkling the yeast on the foam will leave some yeast outside of the liquid which is no good. I will definitely rehydrate the yeast with water or wort in a sanitized container and pitch that slurry. If you stir, remember that is has to be gentle, max 100rpm on a stir plate or equivalent. Agitation (over 100rpm) during rehydration is the main cause of loss of viability in the yeast.

 

If it were a $5 package of yeast, I'd mention that many small batch (and one gallon batch) probably use partial packages. Personally, for my one gallon batches, I pitch a quarter package & put the rest in the fridge for another batch (rubber band to close it tightly, others probably vacuum seal the package). Yup, the beer comes out fine.

But 500 gram bricks appear to be around around $100 and I have no experience with this type of packaging. Maybe it scales up, maybe to doesn't.

 

I just used a partial pack of S-189 that was in the refrigerator for 2 full years, and it started up just fine within 24 hours. Not vacuum sealed, no rehydration, no problem.

 

I think the core reason is companies playing it safe honestly. Almost every other product in general lasts way longer than their supposed expiration date too. It's not like the rest of the pack is exact. These numbers are just what they deem to be safe with no risk of getting sued.

 

https://www.lallemandbrewing.com/en/united-states/products/brewing-yeast/ has a "storage" tab which offers a summary explanation. Recent (didn't see it in the current Fermentis information) information for Fermentis was similar. I'm only looking at yeast labs this time - but the last time I looked, advice for MJ branded yeast would be similar.