Dry Yeast Email from Ferments

Ingredients
1

I had some questions about dry yeast that I emailed Ferments about recently. I thought the group would enjoy the discussion.

Q: I have enjoyed using Fermentis dry yeast because of the storage convenience. I especially like the beer brewed with the 34/70 lager strain. I was surprised that the cell count per gram was lower than expected, specifically on the lager yeast. Can you briefly explain why dry yeast is “different” from liquid cultures and why it initially needs less? Also, why is the lager cfu/g significantly lower than the ale?

I have read that dry yeast has more sterols and glycogen in reserve before they are put into stasis (which is why it doesn’t need aeration) and was wondering if that was why the initially required cell count is lower than the 1 million cells per ml per degree Plato guidelines.

Thanks for your help.

Response:
KREITER Bryan - Fermentis
Jan 31, 2023, 10:07 AM

to me

Hi Keith,
I’m happy to hear Fermentis yeast is working well for you. The primary advantage vs liquid is ease of use, which includes the ability to direct pitch or rehydrate as well as shelf stability. With performance comparable to liquid cultures, it just makes a lot of sense for many brewers. The advantage of liquid is the sheer variety of strains and genetics. Not all strains can be dried successfully, so we will never have the same variety.

The difference in the cell concentration is mainly related to a difference in cell size. Cell size varies between strains, and lager cells tend to be larger than ale cells, thus fewer per gram. Another factor, though minimal, is that pastorianus is more difficult to dry. This resulted in slightly lower viable cells per gram for lager vs ale. Improvements in the past ten years or so have closed this gap and the viability for ale and lager is now virtually the same. I was told that we may adjust the spec for SafLager upward to be in line with SafAle in the near future, but this has not happened yet.

What you heard about sterols and glycogen is accurate.  Fermentis yeast is produced in purely aerobic condition in a batch fed process, maintaining sugar concentrations below 0.5%. This ensures all the sugars are used for biomass and no alcohol is produced during propagation (no alcohol stress).  Most liquid producers do not achieve pure aerobic condition (but close) and do not batch feed the sugars. When sugar concentration is higher than about 0.5%, the Crabtree effect comes into play and alcohol is produced. Alcohol is a stressor and our yeast have never been exposed to this stress. The saturation with oxygen allows the yeast to produce ample fatty acids, sterols, glycogen, then we dry them and preserve them in this state. They have all the building blocks they need for growth and a complete fermentation. This is why we say, when pitching a fresh brick, that oxygenation is not necessary (no harm if you do). For lack of a better term, they are “pre-oxygenated.”  In dry form, the fatty acids, sterols, viability, vitality and all other factors are stable. In a liquid culture, the cells can be consuming these reserves and viability and vitality will be decreasing steadily from packaging to the time of use. Our yeast can begin growing with the reserves they already have and liquid cultures will need to synthesize the fatty acids and sterols they need to grow (oxygen required).

If you are fermenting >18 plato, I would recommend rehydrating the yeast and oxygenating the wort. I say this because our studies were all in conditions below this, so we can’t say with certainty that there is no benefit above this point.

Lastly, we may in the future make some refinements to pitching rates for some strains. The rates will still be dry mass based, but might be more like grams/ml/Plato. Pitching rates are more important for some strains than others.  In our studies of SafLager W-34/70, pitching rate had little effect on fermentation kinetics or flavor. For BE-256, if you pitch too much in lower gravity wort, you can get sulfur….

I hope this helps! Take care!
Bryan

2

That response is packed full of great information. Much of it is well known but some is new like the future pitch rate adjustment. Thanks for posting it Keith.

3

My main question was why the recommended cell count was actually lower for dry yeast than for liquid yeast, but he filled in a  lot of extra stuff as well. I didn’t;t post it because it was just for my personal information. But with all the recent comments about dry yeast, I thought it had some relevancy.

4

In our studies of SafLager W-34/70, pitching rate had little effect on fermentation kinetics or flavor. For BE-256, if you pitch too much in lower gravity wort, you can get sulfur….

As a small batch brewer (3 gallons into fermenter) that always pitches a full pack of yeast (dry or liquid) I have always wondered if my overpitching could cause problems.  I guess the answer is “probably not, but maybe?”.

5

I’m anxious to see their new pitch rate recommendations. But I wonder how they will get the word out.

6

i sent in the email form asking if they have or would make a lallemand style pitch calculator and they never replied.

7

Maybe that’s a touchy subject for them - they seem to be good about answering questions in general. In fact, once I emailed and asked about an inconsistency in their description of a yeast strain. They said it was an error, thanked me for pointing it out, and sent me about 15 yeast packets of various strains to show their appreciation - also a beer glass. I was very impressed.

8

loooooooooool then i am ready to send them a whole bunch of info about inconsistencies in their often absurdly labeled yeast packets. im guessing that was the US05 temperature range misprinting/error?

9

Yeast packet info vs web site info: evidence suggests favoring web site info.

From  Brewer's yeast strains - Our range of active dry yeast for beer - Fermentis

eta: personally, I go to the current “landing page” for a strain and then follow the links to the PDFs. Direct links to PDFs may, over time, lead to product information sheets that are not the most recent.

10

My question was: "Your web page for BE-256 shows it to be POF negative in the “SAFALE™ BE-256 OVERVIEW” section. But below, there is a statement “It produces several flavor active components, such as as fruity esters and phenolic / spicy components, at high concentrations.” I’m wondering if it is POF+ or POF-.

Secondly, I can’t find whether it contains cerevisiae var. diastaticus. I would like to know whether BE-265 contains it, as well as knowing how to determine whether other Fermentis yeasts contain it."
Fermentis reply: " Your remark is very pertinent, the SafAle BE-256 is POF -, its main characteristic is to produce esters especially isoamyl acetate,

For your second question, no the SafAle BE-256 is not diastaticus, in our range of yeasts for homebrewers only the SafAle BE-134 and WB-06 are diastaticus,

Your message allows me to realize that our webmaster did a mistake on the webpage of the SafAle BE-256, the text you have highlighted is coming from another page and shouldn’t appear here, Can I offer you a swag bag to thank you for your help?"

11

Many thanks for posting this. I often keep links to web pages so that I can access them directly. Apparently, that isn’t a good idea. I’m surprised that Fermentis would keep outdated PDFds on the internet that people could use. In some cases it would be ok, but not ideal. But I imagine that in some cases there are changes to the products, and using old procedures would be a problem.

12

It takes a LOT to overpitch. I brew 3 gallon batches and just toss in the entire pack (dry) all the time. Two packs for lager.
For milds and ordinary bitters I like Muntons which comes in smaller packs.

13

I agree that it takes a lot to over pitch. But, if you want to get the pitch rate right, just measure the yeast in a sanitary container on a grams scale. It couldn’t be easier.

14

thanks for that message. yeah BE-256 is not diastaticus and it is a beast and yeah certainly POF-. in flavour i relate it to what piraat and gulden draak taste like in a strong beer.

15

Most web sites seem to assume that one will access PDFs from the “landing page” rather than bookmarking the PDF directly.  Sometimes a site will overwrite the old PDF with the new PDF; sometimes a site will use a new name for the PDF.

Specifically with yeast product information PDFs, things don’t change that much with the newer versions.  A couple of years ago, when I was tracking them more closely, I found some older (2014/2015) ones in the “internet archives”.  Pitching dry was an option then.

The strength of starting with the “landing page” is that one can catch those occasional notices (e.g. Fermentis using up old packaging).