Fundamental shift in yeast starter preparation?

[Bassman2003]

I agree, kind of nebulous. "Normal" would be normal (13P wort). Where this discussion makes sense to me is attenuation. Using the normal 13P methods, it seems good attenuation is tied to a numbers game. More yeast often results in better attenuation in a shorter time frame. Less of these cells results in decent attenuation in a longer time frame. This suggests the cells themselves might be on the tired or weak side while the 2P cells seem to be able to do the same job with fewer workers. Thus showing that the health of the 2P cells allows for better performance. Flavor is unknown as you stated. (This is assuming that the examples in the table shown above were pitched into a fermentation).

 

[McMullan]

I wouldn't read too much into the claims yeast propagated in 2P wort express improved vitality compared with yeast propagated in higher gravity starter worts. It wouldn't surprise me, because even relatively low ethanol levels represent a significant stress factor in the fermentation environment. But it is more likely a very short-term effect that disappears and seems to overlook relatively high vitality of repitched freshly harvested yeast cells. - why serial repitching is practiced post propagation.

 

[Bassman2003]

Good points. I think this space needs some more experimentation to solidify any benefits. There could be some there there but results in finished beers would be needed.

 

[IslandLizard]

Gordon Strong has reported that the often makes lagers and just pitches a single smack pack. Being a 4 time Ninkasi winner, he should know what beer should taste like. How does he get by without making a starter? You can't get much cheaper on starters than not making one.

Age and origin of that smack pack has much to do with the vitality and live cell count. I don't want to discredit Gordon Strong, but he may not obtain his yeast in places and at times, most homebrewers typically buy theirs: on a whim at their local store, or online, the yeast being 2-4 months old, on average, with an unknown history.

We don't know Gordon's batch size either... Maybe he brews 2 or 3 gallon batches. One fresh smack pack should work splendidly.

Also, a 1.040-1.045 OG Lager is similar to most starter gravity. With good wort oxygenation and pitching a fresh, highly vital pack, it may work very well.
One such pack in a Doppelbock would likely have a whole different outcome.

[Gordon Strong...] How does he get by without making a starter?

Maybe you can ask him?
Then report back to us how and under what conditions it works for him.

 

[CascadesBrewer]

I think they called it "under attenuated" because it was less attenuated than the attenuation they got from the non-typical process.

In the study they got the best attenuation from pitching harvested yeast, the worst attenuation from yeast built up with the normal propagation wort, and the attenuation of the yeast propagated in the low gravity/high nitrogen wort was in the middle. So they were using the repitched yeast as the base line to judge "underattenuation." I am not sure I recall seeing any other yeast performance metrics in the study (like lag time, or time to FG).

 

[CascadesBrewer]

We don't know Gordon's batch size either... Maybe he brews 2 or 3 gallon batches. One fresh smack pack should work splendidly.

I am not sure what Gordon has said in other venues. From his book "Brewing Better Beer" he says:

"There are two main ways I use yeast. Either I'm working with fresh yeast, or I'm reusing yeast from an existing batch. If I'm going to pitch new yeast, I will almost always make a starter to get the fermentation starting quickly." (page 130) There is some more info on his process for making a starter (1L with 85 grams of DME and yeast nutrient), and his process for working with harvested yeast.

 

[CascadesBrewer]

One open question I have about the low gravity starters is about the type and amount of "yeast extract" used. The extract used by the paper is "yeast extract 19512, OrganoTechnie S.A.S., France" which I have not seen listed for sale. Info: Yeast Extract - Organotechnie, fermentation and diagnostic peptones

The paper lists using 16g of yeast nutrient per L for the low gravity starter (plus some zinc). Depending on the purchase price, 16g per L of Fermaid-O or Fermaid-K would add about $1.50 to $4.00 to a 2L starter, negating any cost savings in DME. If instead a mix of say 1g/L of a yeast nutrient + 5g/L of DAP could be used, that would be around $0.80 for a 2L starter.

 

[McMullan]

I don't think 'lab grade' yeast extract from different suppliers is variable enough to matter, tbh. I've used several brands without noticing any difference. They all stink as bad as each other. But it is very expensive to use at the suggested rates beyond millilitre volumes. Cervomyces, in bulk, might actually be more viable, economically I don't think yeast extract is equivalent to fermentation 'aids' either. Yeast extract is so much more than a N source, which exposes another issue with the research, I'd say.

 

[onlyhere4science]

In the study they got the best attenuation from pitching harvested yeast, the worst attenuation from yeast built up with the normal propagation wort, and the attenuation of the yeast propagated in the low gravity/high nitrogen wort was in the middle. So they were using the repitched yeast as the base line to judge "underattenuation." I am not sure I recall seeing any other yeast performance metrics in the study (like lag time, or time to FG).

Need to remember statistics here... The paper shows no statistically significant difference in attenuation between harvested yeast and yeast propagated in ANY wort gravity that included nitrogen to achieve a C:N at 100. Harvested yeast did not perform statistically better, with the exception compared to yeast propagated in low nitrogen wort, and this difference increased as OG increased.

In the study they got the best attenuation from pitching harvested yeast, the worst attenuation from yeast built up with the normal propagation wort, and the attenuation of the yeast propagated in the low gravity/high nitrogen wort was in the middle. So they were using the repitched yeast as the base line to judge "underattenuation." I am not sure I recall seeing any other yeast performance metrics in the study (like lag time, or time to FG).

Lag time for propagation and time to reach end of fermentation were all reported in the paper... See Figures 2 and 3. Fermentation time increased for yeast pitched in high OG wort. Lag time increased linearly w/respect to OG for yeast pitched in low nitrogen wort.

I wouldn't read too much into the claims yeast propagated in 2P wort express improved vitality compared with yeast propagated in higher gravity starter worts. It wouldn't surprise me, because even relatively low ethanol levels represent a significant stress factor in the fermentation environment. But it is more likely a very short-term effect that disappears and seems to overlook relatively high vitality of repitched freshly harvested yeast cells. - why serial repitching is practiced post propagation.

As a home brewer if you only get one shot to make a beer, seems like you'd want that first beer with propagated yeast that perform optimally. Even pro brewers sometimes only get one tank to ferment and then sell, with no shot to blend with tanks that have harvested yeast. ¯\_(ツ)_/¯¯\_(ツ)_/¯

I agree, kind of nebulous. "Normal" would be normal (13P wort). Where this discussion makes sense to me is attenuation. Using the normal 13P methods, it seems good attenuation is tied to a numbers game. More yeast often results in better attenuation in a shorter time frame. Less of these cells results in decent attenuation in a longer time frame. This suggests the cells themselves might be on the tired or weak side while the 2P cells seem to be able to do the same job with fewer workers. Thus showing that the health of the 2P cells allows for better performance. Flavor is unknown as you stated. (This is assuming that the examples in the table shown above were pitched into a fermentation).

Seems like there is some confusion here. The paper reports that the same number of cells were pitched in the fermenters. Pitch rate in the fermenters was the same. The variable of pitch rate is eliminated. This is outlined in the methods section. They even eliminated the variable of dilution from the prop pitch to ensure volume and pitch rate were the same for all fermentations...

Brewery wort (370 mL) was added to sterilised 450 mL jars. Dissolved oxygen in the wort was 6 mg/L, determined using a HQ30D portable dissolved oxygen meter with a field luminescent DO sensor (Hach, Loveland, CO, USA). The pitching rate was 0.5x106 cells/mL/OG°P. Yeast cultured in YCM were included as a control in separate fermentations with yeast cultivated in high or low C:N media. Yeast were cultured in duplicate as described above into 25 mL of media until late log phase, and the viable cell concentration for each culture was determined. The volume of cells needed to meet the target pitching rate were centrifuged at 3,000 x g for 5 minutes at 22°C. The yeast pellet was reconstituted in 30 mL of wort and pitched into fermenters for a total wort volume of 400 mL.

 

[onlyhere4science]

I don't think 'lab grade' yeast extract from different suppliers is variable enough to matter, tbh. I've used several brands without noticing any difference. They all stink as bad as each other. But it is very expensive to use at the suggested rates beyond millilitre volumes. Cervomyces, in bulk, might actually be more viable, economically I don't think yeast extract is equivalent to fermentation 'aids' either. Yeast extract is so much more than a N source, which exposes another issue with the research, I'd say.

They do kinda mention this. I def think components of yeast extract that were non-nitrogen likely contributed positively. Def something future research could build on. While they say they interpreted results based on nitrogen (as that's what the recipes were based on), anyone could replicate the recipes and see what other factors besides metals were different and therefore potentially contributing. They could then go on to modify those non-nitrogen comments to see how performance is affected.

While the added nutrients and metal ions from yeast extract could have some impact on performance compared to standard wort, the interpretation of results in this study is focused on the differences in available sugar and nitrogen.

Future research can build on these results by investigating why yeast cultivated in standard wort with a high C:N ratio leads to sluggish and stuck fermentations. If wort was supplemented with FAN in the subsequent fermentation, could yeast overcome the deficiencies generated during propagation? Additionally, the scalability of this propagation protocol should be assessed to determine the impact on large scale fermentation performance. Finally, questions remain on the impact on the organoleptic quality of beer produced with yeast propagated under different conditions.

 

[CascadesBrewer]

Need to remember statistics here... The paper shows no statistically significant difference in attenuation between harvested yeast and yeast propagated in ANY wort gravity that included nitrogen to achieve a C:N at 100. Harvested yeast did not perform statistically better, with the exception compared to yeast propagated in low nitrogen wort, and this difference increased as OG increased.

Thanks for the clarification...I need to take a closer run through of the article text and not just look at the graphs.

 

[McMullan]

Need to remember statistics here... The paper shows no statistically significant difference in attenuation between harvested yeast and yeast propagated in ANY wort gravity that included nitrogen to achieve a C:N at 100. Harvested yeast did not perform statistically better, with the exception compared to yeast propagated in low nitrogen wort, and this difference increased as OG increased.


Lag time for propagation and time to reach end of fermentation were all reported in the paper... See Figures 2 and 3. Fermentation time increased for yeast pitched in high OG wort. Lag time increased linearly w/respect to OG for yeast pitched in low nitrogen wort.


As a home brewer if you only get one shot to make a beer, seems like you'd want that first beer with propagated yeast that perform optimally. Even pro brewers sometimes only get one tank to ferment and then sell, with no shot to blend with tanks that have harvested yeast. ¯\_(ツ)_/¯¯\_(ツ)_/¯


Seems like there is some confusion here. The paper reports that the same number of cells were pitched in the fermenters. Pitch rate in the fermenters was the same. The variable of pitch rate is eliminated. This is outlined in the methods section. They even eliminated the variable of dilution from the prop pitch to ensure volume and pitch rate were the same for all fermentations...

Brewery wort (370 mL) was added to sterilised 450 mL jars. Dissolved oxygen in the wort was 6 mg/L, determined using a HQ30D portable dissolved oxygen meter with a field luminescent DO sensor (Hach, Loveland, CO, USA). The pitching rate was 0.5x106 cells/mL/OG°P. Yeast cultured in YCM were included as a control in separate fermentations with yeast cultivated in high or low C:N media. Yeast were cultured in duplicate as described above into 25 mL of media until late log phase, and the viable cell concentration for each culture was determined. The volume of cells needed to meet the target pitching rate were centrifuged at 3,000 x g for 5 minutes at 22°C. The yeast pellet was reconstituted in 30 mL of wort and pitched into fermenters for a total wort volume of 400 mL.

Indeed, as I typed above, the data are very limited. But I'm wondering why anyone would express any willingness to accept the authors' conclusions - opinions, strictly - regardless The hypothesis really isn't that difficult to test. The research was published over 2 years ago. The lack of confirmation is deafening, and usually means the research findings weren't as valid as assumed, in terms of the authors' suggested benefits. I could be wrong, there might be a flurry of better designed experiments published at some point, to confirm the authors' research, but, until then, I'm content doing what I do to make yeast starters. Mainly because it seems to work very well, for some reason.

 

[mashpaddled]

Both the podcast and the brulosophy experiment are brutally wrong. I have no idea why anybody pays attention to them and the twenty vagrants in their garage.

Start with the premise that yeast given the most healthy and complete diet and compare them to yeast given a diet primarily of sugar, the yeast with the healthy and complete diet reproduce more favorably. If you start from an obvious place, you end up at the same conclusion as the paper.

The purpose of that kind of research is to help large breweries (and distilleries) produce repeatable beers on a repeatable timetable. Under those objectives, you want healthy yeast to perform efficiently and fully attenuate every time. You don't want sluggish or incomplete fermentations leading to production delays and batch variations. As a homebrewer, a few extra days in the tank for a few extra gravity points may not be a big deal. She's exploring whether a cost efficient balance to lab conditions (using expensive growth media) versus the usual starter technique exists and if so, whether it produces a better result. There are some attempts in the thread to extract entirely different points from her research.

 

[onlyhere4science]

Indeed, as I typed above, the data are very limited. But I'm wondering why anyone would express any willingness to accept the authors' conclusions - opinions, strictly - regardless The hypothesis really isn't that difficult to test. The research was published over 2 years ago. The lack of confirmation is deafening, and usually means the research findings weren't as valid as assumed, in terms of the authors' suggested benefits. I could be wrong, there might be a flurry of better designed experiments published at some point, to confirm the authors' research, but, until then, I'm content doing what I do to make yeast starters. Mainly because it seems to work very well, for some reason.

"I could be wrong" nah ur definitely right - it's totes crazy there hasn't been another literature article published yet on this very specific topic which all labs and all brewers are paying close extremely close attention to. I assume you read the journal article immediately when it came out like apparently the rest of the world's scientists so you could hop on the train to proving or disproving? I mean considering it takes 6 mo - 1 yr to publish in a peer-reviewed journal, the research itself by these would-be labs wouldn't take any time at all...surely not! These things are so easy to test as u say! Resources are most definitely unlimited and freely distributed by these labs, especially during COVID!!

Deafening indeed. Thank you for reminding us how the science cycle works. <3

I say this as a quality tech in a small brewery with very little resources who would love to test this out, kinda why I came here to see if any home brewers were taking it on after I heard the podcast. But idk, what do I know. ¯\_(ツ)_/¯

 

[Bassman2003]

Seems like there is some confusion here. The paper reports that the same number of cells were pitched in the fermenters. Pitch rate in the fermenters was the same. The variable of pitch rate is eliminated. This is outlined in the methods section. They even eliminated the variable of dilution from the prop pitch to ensure volume and pitch rate were the same for all fermentations...

Brewery wort (370 mL) was added to sterilised 450 mL jars. Dissolved oxygen in the wort was 6 mg/L, determined using a HQ30D portable dissolved oxygen meter with a field luminescent DO sensor (Hach, Loveland, CO, USA). The pitching rate was 0.5x106 cells/mL/OG°P. Yeast cultured in YCM were included as a control in separate fermentations with yeast cultivated in high or low C:N media. Yeast were cultured in duplicate as described above into 25 mL of media until late log phase, and the viable cell concentration for each culture was determined. The volume of cells needed to meet the target pitching rate were centrifuged at 3,000 x g for 5 minutes at 22°C. The yeast pellet was reconstituted in 30 mL of wort and pitched into fermenters for a total wort volume of 400 mL.

Thanks. I am confused a little on the volumes of the starters as they would need to be different if the final pitches were all the same cell count. But, this should hopefully clear away the idea that underpitching is somewhat part of the experiment.

 

[onlyhere4science]

Thanks. I am confused a little on the volumes of the starters as they would need to be different if the final pitches were all the same cell count. But, this should hopefully clear away the idea that underpitching is somewhat part of the experiment.

NP! The volume of the props produced more cells/mL than needed to meet the pitch rate target of the fermenters/jars.

From my understanding of the methods section, they withdrew the volume of cells from each prop required to hit the fermenter pitch target, spun the cells down to get rid of the prop liquid, reconstituted the pellet in the wort they would be fermenting in, and added that to the ferm. So all the ferms started with the same total volume and the same total amount of cells / mL.

 

[McMullan]

"I could be wrong" nah ur definitely right - it's totes crazy there hasn't been another literature article published yet on this very specific topic which all labs and all brewers are paying close extremely close attention to. I assume you read the journal article immediately when it came out like apparently the rest of the world's scientists so you could hop on the train to proving or disproving? I mean considering it takes 6 mo - 1 yr to publish in a peer-reviewed journal, the research itself by these would-be labs wouldn't take any time at all...surely not! These things are so easy to test as u say! Resources are most definitely unlimited and freely distributed by these labs, especially during COVID!!

Deafening indeed. Thank you for reminding us how the science cycle works. <3

I say this as a quality tech in a small brewery with very little resources who would love to test this out, kinda why I came here to see if any home brewers were taking it on after I heard the podcast. But idk, what do I know. ¯\_(ツ)_/¯

You'll need some wort, yeast extract, yeast, microscope and a hydrometer to monitor fermentation performance.

 

[onlyhere4science]

You'll need some wort, yeast nutrient, yeast, microscope and a hydrometer to monitor fermentation performance.

That’s not going to get a paper published, but sure…

 

[McMullan]

That’s not going to get a paper published, but sure…

It's pretty much what was done by the authors of the paper being discussed here. Why do you need to publish a paper about it? Aren't you more interested in testing the hypothesis for yourself, in your own brewery environment? Is there a business case to justify it?

 

[onlyhere4science]

It's pretty much what was done by the authors of the paper being discussed here. Why do you need to publish a paper about it? Aren't you more interested in testing the hypothesis for yourself, in your own brewery environment? Is there a business case to justify it?

I was really just here to see if others had tested it… but of course I’d be happy to sit down and answer these personal questions that pertain to my own career situation and curiosity in extensive detail for you to ruminate on and apply to the broader discussion we were having on why there isn’t a huge amount of other publications that built on this work. I’ll get right on it.

 

[McMullan]

They were rhetorical questions really. Don't waste any more time on me. You'd be much better off spending your time scribbling down a simple experimental design and just getting on with that instead. Let us know how it goes

 

[onlyhere4science]

They were rhetorical questions really. Don't waste any more time on me. You'd be much better off spending your time scribbling down a simple experimental design and just getting on with that instead. Let us know how it goes

Will do! Thanks mate.

 

[bionicbelly]

When I grow up yeast, I start with a frozen 50ml vial. Go to 250ml of wort then ~2L. I pressure can my wort so I make a single mason jar with double strength wort and dilute with water. So I am seeing some opportunity to increase the dilution a bit as well as increasing yeast nutrient. While my container is limited to ~3L, I could probably add some more water and a little less wort. This is with an assumption that the C:N ratio has a linear application from high to low.

This is exactly my method as well. Could be fun to do a side by side using the same amount of concentrated wort, and change the final concentration to see what happens. I've got a 5L flask, so I could have the room to do this.

 

[troxerX]

Moving forward, does anyone that went through the paper want to give it a try tabulating a quick recipe for 2L, 3L, 5L starters for (g/l) DME, dextrose, fermax (or Wyeast nut), yeast extract, magsulf, zinc, calcium chloride?

 

[bionicbelly]

Moving forward, does anyone that went through the paper want to give it a try tabulating a quick recipe for 2L, 3L, 5L starters for (g/l) DME, dextrose, fermax (or Wyeast nut), yeast extract, magsulf, zinc, calcium chloride?

This would be sweet.

 

[troxerX]

This would be sweet.

The group could start using it and report back for everyone to benefit. I have a few yeast starters to prep myself and I could be the first to report if someone were to take a stab later today. By the way the paper may not mention or be specific to some of the ingredients I listed above (recommended amounts will be great)

 

[bionicbelly]

Contains: Proprietary blend of vitamins, minerals, inorganic nitrogen, organic nitrogen, zinc, phosphates and other trace elements.
This is Wyeast yeast nutrient. I'm not sure we will be able to actually get to a 100 C:N ratio with this. Which sucks, cause this is what I have.

 

[VikeMan]

Contains: Proprietary blend of vitamins, minerals, inorganic nitrogen, organic nitrogen, zinc, phosphates and other trace elements.
This is Wyeast yeast nutrient. I'm not sure we will be able to actually get to a 100 C:N ratio with this. Which sucks, cause this is what I have.

Why not? Because the nutrient contains some "carbon" or because the amount of nitrogen is unknown (but probably knowable)? If the former, the carbon in the nutrient wouldn't count. The carbon that would matter for the C:N ratio is in carbohydrates (sugar).

 

[bionicbelly]

Contains: Proprietary blend of vitamins, minerals, inorganic nitrogen, organic nitrogen, zinc, phosphates and other trace elements.
This is Wyeast yeast nutrient. I'm not sure we will be able to actually get to a 100 C:N ratio with this. Which sucks, cause this is what I have.

Why not? Because the nutrient contains some "carbon" or because the amount of nitrogen is unknown (but probably knowable)? If the former, the carbon in the nutrient wouldn't count. The carbon that would matter for the C:N ratio is in carbohydrates (sugar).

Because the amount of nitrogen is unknown. As the product page says, it is proprietary, and the wyeast contact page does not look like they want to answer questions from homebrewers.

 

[bionicbelly]

Not sure how important getting to an exact 100 C:N ratio is though, as the experiments only test 850 and 100 C:N ratios. I mean, 200 might be pretty good? I don't know. The YCM used was 100 C:N, so that's why that ratio was used.