Dry yeast cell counts

[Andy Brosius]

Apologies in advance for the painfully basic question, but how many yeast cells are found in a small (11 gram) packet of dry yeast? I'm finding conflicting info - Palmer suggests 100 billion, but BeerSmith says 200 billion. I can't find any information on the Safale website.

What I can say is that I routinely had fermentation issues (off flavors) when using only 1 pack of dry yeast. Since increasing to 2 (for medium gravity ales), I'm getting much more consistent results. I do rehydrate (sometimes with wort, sometimes with sterilized warm water).

Thanks!

 

[RM-MN]

Do a search on yeast cell counting and look at the possible errors in that. Safale may not want to publish the cell count because of the potential errors that are inherent in the process.

The biggest factor in off flavors in your beer are in the fermentation temperature. Do you have a way of controlling that? If not, do some reading about how to control it.

 

[VikeMan]

Apologies in advance for the painfully basic question, but how many yeast cells are found in a small (11 gram) packet of dry yeast? I'm finding conflicting info - Palmer suggests 100 billion, but BeerSmith says 200 billion. I can't find any information on the Safale website.

If you really want to know, get a sachet of yeast, a microscope, a hemocytometer, pipettes, and some distilled water. And some methylene blue, if you want to know how many of the cells are actually viable. Count away!

Then repeat for each strain, because by weight (11 grams or whatever), the count could vary by strain.

I'm kind of kidding, but I may actually do this myself, because the anecdotal "counts" are all over the place, as you found. OTOH, I'm not really a dry yeast guy, so I'm really not sure if I care enough.

 

[BrewnWKopperKat]

Safale website

In the BE-134 product information sheet (PDF), there is this: Typical analysis: Viable yeast > 1.0 *10**10 cfu/g

Are you using a phone or tablet to access their site? The desktop/laptop download section for the BE-134 page looks like this.

where the flags are the "clickable" links. On my iPad, the flags look like individual dots. If I zoom to maximum size, they are clickable.

 

[VikeMan]

In the BE-134 product information sheet (PDF), there is this: Typical analysis: Viable yeast > 1.0 *10**10 cfu/g

So, an 11.5 gram pack of BE-134 would have 11.5 grams x 10B cells/gram = 115B cells

 

[dmtaylor]

~200 billion. And it remains viable for YEARS in refrigeration, not weeks or months as MrMalty or other sources might have you believe.

LENGTHY discussions surrounding this topic:

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

 

[eric19312]

I spent a lot of time down this rabbit hole and finally decided it doesn't actually matter. 1 pack is enough for a beer up to 1.060 use more beyond that. Double it for cold fermented lager, one pack is fine for warm fermented lager.

Safale does report a number on the yeast data sheet that comes in at something like more than 60 billion cells in a packet of US-05. I think the disconnect comes from trying to apply cell count formulas developed for liquid yeast to dry yeast. Just don't do it. One pack is fine. Also keep your dry yeast packs dry and in your fridge and just forget about adjusting for viability based on manufacturing date.

 

[Andy Brosius]

Thanks all - a lot of excellent information here, though I guess it's not as straightforward as I had thought.

RM-NM: I use a chest freezer with an inkbird, though I've been having some problems with temperature fluctuations (I actually started another thread about it). That certainly could explain it, though some people seemed to think the swings I was seeing wouldn't actually impact the wort to any great extent.

BrewnWKopperKat: Thanks for finding that - very useful indeed. And thanks, Vikeman, for translating it into something that can be understood even by an innumerate like myself.

dmtaylor: So for 200 billion, would you pitch 2 packets of dry yeast? Thanks for that link - I'll definitely have a read.

eric19312: Interesting. I've been having consistency issues which I think can attributed to stressed yeast, and increasing to 2 packets seemed to help considerably. I should admit, rather sheepishly, that when using 1 packet I was not actually rehydrating first. When I increased to 2 packets, I also started rehydrating. The results have been decent, so I'm kind of scared to test out a single packet with rehydration.

 

[Jim R]

I just decided to now only buy liquid yeast (as fresh as possible) and then take the time to make a yeast starter the day before brew day. It isn't that expensive, it doesn't take much time at all and the results are virtually guaranteed with very fast initiation of fermentation.

 

[dmtaylor]

dmtaylor: So for 200 billion, would you pitch 2 packets of dry yeast? Thanks for that link - I'll definitely have a read.

My conclusion from everything I've learned not just through reading and arguing with people but also from personal experience:

1/2 pack is plenty for 5-6 gallons of ale of say 1.065 or less. If higher OG then use 1 full pack.

1 pack is plenty for 5-6 gallons lager <1.065, or if really high OG then use 2 packs.

That's a pretty safe set of guidelines, has never failed me in a zillion batches. I almost always used dried yeast, love dried yeast whenever possible.

And, by the way, I NEVER rehydrate. I just sprinkle on top of the wort. I don't even mix it in. I don't aerate. All of that is a waste of time and effort, I promise.

 

[Andy Brosius]

Jim R: Liquid yeast is definitely better, but unfortunately where I live it isn't available. The next time I manage to get some, I should start yeast farming.

dmtaylor: If what you're saying is true, then I have no idea what may have been causing my beers to be so inconsistent. I've never had a bad batch with liquid yeast, but dry yeast has been unpredictable.

 

[thehaze]

What exactly was wrong with the batches fermented with dry yeast? There are lots of commercial breweries and many that make amazing beer, using dry yeast, so I don't think the quality of the yeast could have been an issue, unless you underpitched or something else entirely happened. But if you can tell us more - recipe, mash temp., pH, pitch rate, fermentation temp. and schedule, etc. - that could help us, help you.

 

[BrewnWKopperKat]

edited: let's take this in a different direction.

A couple of years ago, once we "got past "You must rehydrate dry yeast or you will kill half the yeast!", there were a number of interesting discussions around the idea of making a starter using dry yeast for very specific reasons.

For many people, almost all the time, there is no reason to make a starter.

People who were unable to successfully order liquid yeast online and those where were "price sensitive" to the cost of yeast in general found that dry yeast, with a starter, was a good way to brew. IIRC, in these topics, there was the occasional "I find that IQ-42 brand dry yeast tastes better after I've made a starter" post.

Sorry, no science and no links (at the moment). I may have saved some links in my notes. If someone is interested in the links, I'll see what I can find over the next couple of days.

 

[eric19312]

eric19312: Interesting. I've been having consistency issues which I think can attributed to stressed yeast, and increasing to 2 packets seemed to help considerably. I should admit, rather sheepishly, that when using 1 packet I was not actually rehydrating first. When I increased to 2 packets, I also started rehydrating. The results have been decent, so I'm kind of scared to test out a single packet with rehydration.

I did go back and re-read your original post after posting and realized this might be reasonable objection. However you also mention you are still working on temperature control. Perhaps overpitching the dry yeast is helping you overcome flaws that could also be addressed with temperature control. With the overpitch the yeast are spending less time in their growth and reproduction phase and get on to production of alcohol sooner. Ester production is highest during growth and reproduction. So combining a too hot fermentation with a relatively low pitch might be recipe for a lot of ester expression--not what you want if you were planning a clean american ale yeast fermentation.

I harvest and reuse US-05 but always have spare dry packs on hand. I do find that a fresh dry pitch will take close to 24 hours to start bubbling while my harvested pitches go much faster but my guess is that is a function of cell count. With good temperature control both beers turn out as expected.

I have also stopped rehydrating after practicing that for many years. Safale put out some studies showing it had no impact on fermentation vs sprinkle on top of the wort and I see every single yeast handling step as a potential chance for contamination.

 

[friarsmith]

Last year at Homebrew Con, I attended a Fermentis/Safale lecture. It was mainly focused on results of testing 34/70 at various temperatures. The two presenters were technical/lab types. After the lecture, I spoke with one of them and asked "Off the record, how many viable cells are in a standard packet." His answer was "As long as the packet hasn't reached it's expiration and it has been refrigerated, our testing of older packets usually results in at least 150 B, but they're often closer to 200B."

 

[Andy Brosius]

One beer that I've had some issues with is a robust porter (derived from a recipe in Brewing Classic Styles). The first time I brewed it (with liquid yeast), it is magnificent. Since then I've brewed it twice with dry yeast (US-04), and both times it was off. The first time there were clear off-flavors which to me were indicative of poor fermentation (though the alcohol content was high), and the second time it just tasted a bit rough - a friend described it as "hot and boozy." I'm afraid I'm not proficient in identifying specific flavor compounds, but suffice it to say the second and third iterations were not very pleasant.

Here are the details from the most recent attempt:

• Malt: 10.5 pounds Maris Otter, 4.5 pounds Munich, 12 oz Carafa II, 8 oz Carafa III
• Hops: Saaz, Challenger, Willamette 36 IBUs
• Color: 38.5 SRM
• OG: 1.068 / FG: 1.008 (BeerSmith estimated 1.019)
• ABV 7.9% (versus estimated 7.2%)
• Primary fermentation at 65 F, increased to 70 F after 2 days, fined and cold crashed 5 days later

Another recipe I had issues with was an ESB, using Lallemand London ESB English Style Ale yeast. A different yeast, but the same weird off flavor.

 

[Andy Brosius]

eric19312: It could very well be a temperature issue. Because I didn't have the probe attached to the fermenter, there's a good chance the actual wort was outside of the desired temperature range. Your explanation of the extra yeast masking some of the effects of the high temperature seems very plausible.

friarsmith: Very interesting indeed. Did they talk about rehydration at all?

 

[BrewnWKopperKat]

Last year at Homebrew Con, I attended a Fermentis/Safale lecture. It was mainly focused on results of testing 34/70 at various temperatures.

Thanks!

There is also general information from Fermentis here:

• Answers about yeast and fermentation (including some Q&A on rehydration)
• Beer fermentation tips and tricks | only for brewers (follow the links to the PDF)

 

[friarsmith]

friarsmith: Very interesting indeed. Did they talk about rehydration at all?
[/QUOTE]

Yes. IIRC they determined rehydration makes little difference in the fermentation process and finished product. One of the presenters, during the Q & A, went as far as to say "don't bother" with rehydration. In my experience, rehydration does seem to shorten the lag time, at least in terms of visible signs of fermentation.

 

[Novacor]

I just decided to now only buy liquid yeast (as fresh as possible) and then take the time to make a yeast starter the day before brew day. It isn't that expensive, it doesn't take much time at all and the results are virtually guaranteed with very fast initiation of fermentation.

I used to do the same thing. I figured that liquid yeast was better and a more advanced (therefore better) way to homebrew.
I ended up using a packet of dry yeast once after a starter got contaminated with fruit flies and that batch came out just as good as any I brewed with liquid yeast.
Now I still do use liquid yeast if I need to step up the cell count or if I'm looking for a specific strain, but I use us-05 on any recipe that calls for 1056 or 001. Saves me a few steps and a few bucks per batch.

 

[brewbama]

Fermentis recommends .5 g - .8 g per liter wort for Ale. So, 1 pack 11 g will inoculate 22 liters of avg strength Ale. As strength increases inoculation rate should increase up to 17 g per 22 liters.

I much prefer the Lallemand dry yeast pitch rate calculator for a more precise measure. My APA took 13 g BRY-97 for 5.5 gal (21 liters) of 1.050 wort. I used 15 grams then vacuum sealed the remaining pkg for next brew. The mfr says if resealed under vacuum the yeast is good until the expiration date (2 yrs from mfr).

which leads me to a gripe I have with BeerSmith. It only displays 1 digit for pkg of dry yeast. If you load 1.3 pkg it will round down to 1 in the recipe display. Either the display should be X.x pkg or better yet XX grams.

 

[BrewnWKopperKat]

I harvest and reuse US-05 but always have spare dry packs on hand. I do find that a fresh dry pitch will take close to 24 hours to start bubbling while my harvested pitches go much faster ...

p 28 of the Fermentis "Tips & Tricks" (link to PDF) brochure shows a "one day lag" with US-05. The chart also shows a long gradual rise to "full" attenuation. Not likely one could go from grain to glass with US-05 in a week.

The line for S-04 seems to suggest 40% attenuation by day 2 & 50% by day 3. But, as the chart notes YMMV: "Apparent attenuation is indicative and may vary under different conditions."

 

[thehaze]

I've been using 1 sachet for 5-6 gallons with an OG of max. 1.060 for some years. Then at some point, I brewed some beers which I added 2 sachets of yeast. I can't say I noticed huge differences, but for me the batches made with 2 sachets seemed to " pop " more in terms of esters and phenols. Of course, some yeast benefit from underpitching, some don't. For anything higher than 1.075 I will use 3-5 sachets, depeding on OG. My latest Pastry Milk Stout has an OG of 1.103 and finished ( intentionally ) at 1.052. I used 5 sachets. I am still enjoying that beer and it just becomes better. However, I am not saying that 5 sachets is what everyone should use, but the beer turned out on point.

 

[ncbrewer]

I emailed Fermentis about their new recommendation that dry pitching is perfectly fine. I asked about dry pitching on foam. The answer included: "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."

 

[BrewnWKopperKat]

I emailed Fermentis about their new recommendation that dry pitching is perfectly fine. I asked about dry pitching on foam. The answer included: "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."

Has this information changed the way that you brew?

 

[ncbrewer]

Has this information changed the way that you brew?

Based on the latest Fermentis recommendations, I had decided to start dry pitching, but I was concerned about pitching on the foam. I asked if gently stirring after dry pitching would approximate their method. Based on their answer, I decided to continue rehydrating.

 

[brewbama]

Why not fill a portion of the way, add the yeast, then finish filling the FV. That’s the method they recommend. Adding the addition wort halfway thru will knock the yeast down into contact with the beer.

 

[BrewnWKopperKat]

I emailed Fermentis about their new recommendation that dry pitching is perfectly fine. I asked about dry pitching on foam. The answer included: "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."

Was there any mention of anticipated off flavors in the beer when dry pitching onto the foam? Any mention of how long the yeast had to sit on the foam before the off flavors were noticed?

 

[ncbrewer]

Why not fill a portion of the way, add the yeast, then finish filling the FV. That’s the method they recommend. Adding the addition wort halfway thru will knock the yeast down into contact with the beer.

Was there any mention of anticipated off flavors in the beer when dry pitching onto the foam? Any mention of how long the yeast had to sit on the foam before the off flavors were noticed?

I'll answer both of these by showing the whole exchange. The bold font is mine. (I originally just pulled portions to avoid cluttering the thread):
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?

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.

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?

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.

ME:
I understand my situation is not typical and greatly appreciate your giving me a "custom" answer to fit my circumstances. Great customer service.

Edited for clarity

 

[BrewnWKopperKat]

FERMINTIS: ... lower chances of contamination ...

OK - so it's not a off-flavor concern, but a contamination concern.

Personally, I brew smaller batch sizes and don't "top off" - so I don't have a lot of foam to deal with when pitch dry yeast (without rehydration).

I also store open packages of dry yeast more than seven days and, so far, the beer comes out fine.