Starter with dry yeast

[Terek]

Settle down, children....christ, and I thought the mead makers were anal.....easy answer- it's YOUR beer, do what YOU want with it. Unless you're a professional, it's of miniscule importance - making great beer is easy. Everyobody step back, take a breath, and give it a rest.

Yes! Thank you.....this thread is getting out of hand.

 

[big_len]

Given that I know I'm going to be stressing the yeast when it goes into the fermentor due to the large amount of sugars and the upcoming baby boom in the yeast population, I'd much rather go in with yeast that already has the reserves it needs than go in with yeast that will need to replenish those reserves.

I was trying to ask this in a new thread for fear of further cluttering this one. How much of this internal reserve is left after the rehydration process (i.e. the yeast has been in pure water for approx. 30 mins?)

This is not an attempt to contradict what your point, it is a genuine question?

 

[big_len]

Settle down, children....christ, and I thought the mead makers were anal.....easy answer- it's YOUR beer, do what YOU want with it. Unless you're a professional, it's of miniscule importance - making great beer is easy. Everyobody step back, take a breath, and give it a rest.

This is the largest internet forum for discussing the particulars of homebrewing, if this isn't the stage for such rigorous discussion then I don't know what is

 

[boydster]

I was trying to ask this in a new thread for fear of further cluttering this one. How much of this internal reserve is left after the rehydration process (i.e. the yeast has been in pure water for approx. 30 mins?)

This is not an attempt to contradict what your point, it is a genuine question?

Good question, and one I certainly don't know the answer to. The trehalose is the protect the cell from stress... so I would venture to guess that much of it is still available to the cell until it is pitched. The glycogen I would imagine gets used more quickly as it is used to help rebuild the cell walls. I'd love to know if someone else has a better understanding. Otherwise I'll just end up researching it myself but no telling how long it'll be until I have a real answer.

 

[cjgenever]

I was trying to ask this in a new thread for fear of further cluttering this one. How much of this internal reserve is left after the rehydration process (i.e. the yeast has been in pure water for approx. 30 mins?)

This is not an attempt to contradict what your point, it is a genuine question?

Apparently none. There is only enough sustenance for about a half hour from what I understand. The first few seconds are of the most importance. After that the cells can regulate the fluid transfer across the cell membrane. I usually end up hydrating for three to five min.

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[boydster]

Apparently none. There is only enough sustenance for about a half hour from what I understand. The first few seconds are of the most importance. After that the cells can regulate the fluid transfer across the cell membrane. I usually end up hydrating for three to five min.

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What cause would the yeast have for depleting the trehalose? The glycogen has more of a reason to be depleted. Read the link I posted earlier. I ask the question earnestly, but I don't expect that you have the answer. Maybe someone else does though?

 

[big_len]

This dicussion seems to be going in an interesting direction for sure.

I can see that you guys (namely boydster and cjgenever) seem to both indicate that the sustenance/energy aspect of the reserves may well be depleted significantly during rehydration in water.

This trehalose topic sounds interesting though. I must admit I had not heard of it until now. The paper you (boydster) linked earlier seems to indicated that it does not play a signicant role, almost negligible it seems, in energy reserves. But it does indeed state that it is beneficial for stressed yeast, which it further elaborates specifically in response to temperature swings and dehydration/desiccation. It also appears to indicate that yeast naturally produces this compound in preparation for dormancy. I apoligise if I have misinterpretted this as I have only had a brief read and it is late here!

The paper is targeted at yeast survival however, so does it have benefits outside of those I could deduce above? It may well be in that paper but it certainly drifted over my head

 

[boydster]

I think from my initial read through the paper that the yeast during rehydration depend on the glycogen for energy and cell wall restoration and and then use the trehalose to help reduce the shock from being pitched into the wort. I need to research more to really arrive at any sort of conclusion though. I'm not a microbiologist by any means, so I learn as I go and encounter new situations like many others here.

Edit: Check out page 4, it's pretty specific to glycogen. I still stand by my initial thought that glycogen is what will be depleted during the hydration phase, and the trehalose will be more valuable to the cell as soon as the yeast is pitched.

Even according to Fermentis, though, the yeast is fine to keep in water for longer than the 30 minutes without dying or being contaminated, so if that is what you are worried about then take it off your worry list now. Check out their FAQ - it's linked in the Dry Yeast FAQ sticky or you can find it through their website probably (or through strong Google-fu). The issue with not pitching in the first 30 minutes is just losing the initial extra kick that was engineered into the product.

 

[max384]

Regardless of whether this discussion got heated on a few occasions (and I'm not blameless), I'm glad that cjgenever posted it. I've learned a lot from people who have posted here, and I read up on a lot of this myself in order to contribute to contribute to this conversation and for my own knowledge, of course.

Cheers!

 

[boydster]

Hmmmmm...

2. When yeast cells are dehydrated, they don't metabolize glycogen (stored food) to stay alive. As a result, dry yeast cells have healthy glycogen reserves and therefore don't require yeast starters. In fact, starters are detrimental to dry yeast. That's because glycogen gets used up pretty quickly after pitching, and homemade starters are less effective than laboratory propagations at building it back up.

Source: http://oshkoshbeer.blogspot.com/2010/06/joe-walts-on-advantages-of-dry-yeast.html

 

[boydster]

Double hmmmmmmm.....

The first topic will be Glycogen reserves. Glycogen is for animals what Amylopectin is for plants. In yeast, glycogen reserves serve to maintain life up until the point that glucose uptake from wort is possible. Producers of dry yeast (e.g. Danstar, Fermentis, etc.) take special care to make sure that their yeasts have adequate glycogen reserves to improve their survival rates. Interestingly, this is why it is often not advised that one make a starter with dry yeast. Making a starter uses up the glycogen reserves that the producer had included.

Source: http://makinthemtherebeers.blogspot.com/2007/07/perhaps-not-as-technical-tuesday-dry.html

Seems to confirm what kombat was trying to convey and what I also stated earlier. It's best to just use more yeast. A starter will work, sure, but one of the advantages of using dry yeast is the additional glycogen it is packaged with and you aren't maximizing that advantage when you make a starter. You're also depleting the trehalose in the starter, as I referenced earlier.

 

[boydster]

This is straight from Fermentis. It is regarding using "soft sachets" which just means packets of yeast that have some oxygen (and also likely some moisture) in them:

Can I use soft sachets?
No. If the sachet is soft to the touch, the seal has been damaged allowing Oxygen to enter the package. As the yeast enzymes will be activated, the glycogen reserves will be depleted causing a loss of viability over time

Bottom line is that glycogen is the "food" that provides the energy boost and is quickly depleted. The trehalose is used by the cell once it is introduced to the wort.

 

[max384]

Hmmmmm...



Source: http://oshkoshbeer.blogspot.com/2010/06/joe-walts-on-advantages-of-dry-yeast.html

See, this is where I'm not following the reasoning.

Glycogen reserves will be used up whether they're pitched into the wort or pitched into the starter wort. At some point, the yeast must be activated and start doing work, right?

So, I understand that the glycogen stores will be used up in the starter, but why is that a bad thing? At this point, they have nutrients to consume just like they would in the wort. I mean, if they're pitched into the wort, they'll eventually use up their glycogen stores there too and then they must 'fend for themselves.' So why not let them go ahead and use up their glycogen stores in the starter and begin propagating new yeast there before pitching into the wort?

This is really where my disconnect lies. I'm able to follow the reasoning of most of the group that is against making dry yeast starters up until this point.

 

[flars]

Lallemands' response to a question on making a starter with their dry yeast.

http://www.danstaryeast.com/articles/aeration-and-starter-versus-wort

According to what Dr. Clayton Cone has written, minimal amounts of sugars in the starter will produce the best results for increasing cell mass.

The response is to a certain question. The response doesn't address the benefits of a starter.

http://www.danstaryeast.com/articles/encouraging-yeast-growth

 

[big_len]

In yeast, glycogen reserves serve to maintain life up until the point that glucose uptake from wort is possible.

Does this statement indicate that glycogen will not be favoured for "consumption" when glucose is available?

If so, doesn't that mean that glycogen serves no purpose in the presence of glucose ?

EDIT: refined my question

 

[boydster]

See, this is where I'm not following the reasoning.

Glycogen reserves will be used up whether they're pitched into the wort or pitched into the starter wort. At some point, the yeast must be activated and start doing work, right?

So, I understand that the glycogen stores will be used up in the starter, but why is that a bad thing? At this point, they have nutrients to consume just like they would in the wort. I mean, if they're pitched into the wort, they'll eventually use up their glycogen stores there too and then they must 'fend for themselves.' So why not let them go ahead and use up their glycogen stores in the starter and begin propagating new yeast there before pitching into the wort?

This is really where my disconnect lies. I'm able to follow the reasoning of most of the group that is against making dry yeast starters up until this point.

The point is that they already have this glycogen and don't have to do any extra work to be able to metabolize it, so it's additional food and hence, an extra boost. It prevents them from wanting to go dormant while rehydrating and therefore encourages them to get into the reproductive phase more quickly once pitched. If you make a really big starter, the yeast will go into reproductive phase anyway, so that doesn't seem to be detrimental. It's if you make a starter that doesn't encourage much cell growth that you essentially waste that glycogen reserve. Further, making a 3L or even better, a 4L starter isn't always practical, and it's still much easier and (at least, for me) more affordable to just use a second pack in lieu of making a gigantic starter. Also, to maintain that level of activity, you pretty much need to pitch the starter at high krausen or else, again, some of the yeast metabolism will slow down, and most people don't want 3 or 4L of starter wort tossed into their beer.

I think the statement to not make a starter with dry yeast is a generalization, as most any blanket statement is, but I think it's made for good reason. Imagine how difficult it would be for Fermentis to explain all the caveats if they said that making a starter with the dry yeast was OK... "It's OK, but you need to take into consideration ALL of the following variables and then determine if it would just be more effective to buy a second packet." This, from the company that prints on the packet just to "Sprinkle into wort" because informing customers to rehydrate is asking too much. This, in a market where even the liquid yeast companies tell their customers to directly pitch 100 billion cells (at best...) because telling them on the packaging to make a starter might be off-putting. You see what I mean, I'm sure.

 

[max384]

The point is that they already have this glycogen and don't have to do any extra work to be able to metabolize it, so it's additional food and hence, an extra boost. It prevents them from wanting to go dormant while rehydrating and therefore encourages them to get into the reproductive phase more quickly once pitched. If you make a really big starter, the yeast will go into reproductive phase anyway, so that doesn't seem to be detrimental. It's if you make a starter that doesn't encourage much cell growth that you essentially waste that glycogen reserve. Further, making a 3L or even better, a 4L starter isn't always practical, and it's still much easier and (at least, for me) more affordable to just use a second pack in lieu of making a gigantic starter. Also, to maintain that level of activity, you pretty much need to pitch the starter at high krausen or else, again, some of the yeast metabolism will slow down, and most people don't want 3 or 4L of starter wort tossed into their beer.

I think the statement to not make a starter with dry yeast is a generalization, as most any blanket statement is, but I think it's made for good reason. Imagine how difficult it would be for Fermentis to explain all the caveats if they said that making a starter with the dry yeast was OK... "It's OK, but you need to take into consideration ALL of the following variables and then determine if it would just be more effective to buy a second packet." This, from the company that prints on the packet just to "Sprinkle into wort" because informing customers to rehydrate is asking too much. This, in a market where even the liquid yeast companies tell their customers to directly pitch 100 billion cells (at best...) because telling them on the packaging to make a starter might be off-putting. You see what I mean, I'm sure.

I agree it makes sense for them to recommend against making a starter out of dry yeast. Not only is it difficult to explain to the average consumer, as you explained, it's also counterproductive in terms of selling product. They'd MUCH rather recommend buying a second packet of their yeast than to make a starter.

Quite honestly, if making a starter out of dry yeast only served to increase cell count, I'd never even consider it. I'd just buy a second packet, since it would be easier and cheaper. However, it seems to me that a starter pitched at high krausen would be much healthier and start the fermentation faster than an equivalent amount of dry yeast. And this is really why I am interested in this discussion. If I could throw out half of a dry packet and pitch the other half into a starter and then get the original amount in the dry packet back after propagation, I may be willing to do this... Not for higher cell counts obviously, but for healthier yeast... But is this even the case? To me, it makes sense that it would be, but it seems many feel this isn't the case.

 

[boydster]

I don't know how you arrive at that conclusion. The yeast is literally packed with everything it needs to get a healthy start, assuming you rehydrate it, leaving no practical advantage to making a starter for the reason you describe. Making the starter will rob it of its trehalose reserve, so it will experience more of a shock when introduced to the wort. Pitching at high krausen means it won't be starting to slow down metabolism (so you overcome the need for the glycogen reserve), but it will still be subject to the stress of the high sugar wort ( which is the reason the trehalose is built in).

Edit: PLUS, you don't have to pitch the better part of a gallon of starter wort into your beer. Think about that for a second... in a 5 gallon batch, pitching 3/4 of a gallon of starter wort is a pretty big percentage of the final beer. Or you could pitched 230 ml of yeast slurry (2 packs rehydrated with 115 ml of water each) and have the advantage of the additional trehalose reserve. I know which one I would choose.

 

[max384]

I don't know how you arrive at that conclusion. The yeast is literally packed with everything it needs to get a healthy start, assuming you rehydrate it, leaving no practical advantage to making a starter for the reason you describe. Making the starter will rob it of its trehalose reserve, so it will experience more of a shock when introduced to the wort. Pitching at high krausen means it won't be starting to slow down metabolism (so you overcome the need for the glycogen reserve), but it will still be subject to the stress of the high sugar wort ( which is the reason the trehalose is built in).

I got it from the Yeast book discussed earlier:

"The starter's purpose is to create enough clean, healthy yeast to ferment your batch under optimal conditions. The primary focus of a starter should always be yeast health first and increased cell growth second. Many brewers mistakenly focus on cell growth at the expense of yeast health."

Later he says:

"Starters rarely have a negative side; even if there is little yeast growth, a starter helps to revive yeast for fermentation by activating metabolism, and therefore fermentation starts faster."

 

[boydster]

But that is referencing liquid yeast. Dry yeast packets are full of extremely healthy yeast, as long as you rehydrate properly. Liquid yeast is not always very healthy. Things like age and storage temperature play a huge factor in both viability and vitality. That just isn't as much of a concern with dry yeast.

 

[sandyeggoxj]

If dry yeast is so awesome then why aren't all the strains available dry?

Cheaper, no starters, healthier? How could we go wrong?

 

[max384]

WARNING: Long nerdy dense post!

I was reading the article you posted on trehalose earlier boydster, and found a few more articles, and I don't think trehalose protects the yeast against the osmotic stress of the more hypertonic sugar solution in wort, or at least not as much as has been attributed to it here. Rather, it protects against thermal stresses, which is why it is in such high concentrations in dry yeast.

From the article:

Trehalose functions:
-™ Trehalose has the ability to stabilise protein
structure such that in the presence of this
disaccharide many enzymes exhibit resistance to
heat and desiccation.

-™ Trehalose protects cells from temperature
extremes by stabilising membrane structure

-™ Trehalose is a most effective agent for
preventing damage to membranes by its ability
to prevent phase transition events in lipid bilayers

-Trehalose synthesis requires metabolic energy,
whereas no ATP is generated in its dissimilation
(Boulton and Quain, 2001).

It goes on to say:

Trehalose accumulation in the yeast cells has
important consequences for different commercial
applications. The fact is already accepted that high
trehalose levels are important for producing active
dry yeast. In this case, trehalose offers protection
during drying process. It also offers cryoprotection
when yeast is used in frozen dough (Higashiyama,
2002).

My take on this is that it is high in dry yeast because that is necessary in the production of the dry yeast itself, and it is useful in rehydration.

I also found an article titled: "Osmotic Stress Signaling and Osmoadaptation in Yeasts"

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC120784/

It's a very dense read, which I obviously haven't read all of, but from what I've gathered, trehulose doesn't play much of a role in osmotic stress defenses, and the role it does play as an osmolyte is unclear. Glycerol, on the other hand, does primarily protect the yeast cell from osmotic stress, such as putting them into a hypertonic sugar solution.

The pathways for production of glycerol, trehalose, and glycogen all start with intermediates of glycolysis (Fig. ​(Fig.11).11). The three compounds have different physiological roles: glycerol serves as an osmolyte (7, 48, 63, 228), trehalose might be a more general stress protectant and assists chaperones in controlling protein denaturation and renaturation (173, 560, 561), and glycogen is a storage carbohydrate (173).

and later in the article:

It is, however, still unclear if trehalose can serve the role of an osmolyte in S. cerevisiae, as it does in bacteria (280, 580, 581). The role as a protectant may rather be specifically relevant for heat stress and extreme forms of osmotic stress, such as desiccation and freezing (236, 527, 561, 580). Hence, it appears that glycerol serves as an osmolyte for proliferating cells, while trehalose accumulation may rather aim at survival when proliferation has ceased.

and

The trehalose content of commercial baker's yeast preparations may be as high as 20% of the dry mass (622). This high trehalose content, which is achieved by growing cells under constantly low sugar concentrations in a fed-batch system, is believed to protect cells during drying and rehydration as well as serving as an important source for carbon dioxide production during the initial phases of dough leavening.

However, they go on to say

Numerous studies demonstrate a correlation between the cellular trehalose content and the ability to survive diverse stress conditions, ranging from especially heat shock and desiccation to starvation, oxidative stress, ethanol stress, cold stress, freezing, hydrostatic pressure, and osmotic stress (references 139, 158, 173, 429, 560, and 595 and references therein).

Which does mention trehulose as an osmolyte, but this is unclear, as shown here:

A possible role of trehalose in yeast osmoadaptation is supported by the Msn2p/Msn4p- and Hog1p-dependent stimulation of expression of the genes encoding all enzymes in trehalose metabolism (501), the reported sensitivity to high osmolarity of the tps2Δ mutant (61, 238), and the diminished survival after severe osmotic stress of mutants unable to produce trehalose (238). However, yeast cells do not actually accumulate trehalose to appreciable levels after an osmotic shock

Another article I found (which I was only able to access the abstract):

"Trehalose lowers membrane phase transitions in dry yeast cells."

Recent work has clearly demonstrated a direct correlation between the amount of trehalose present in the yeast Saccharomyces cerevisiae and its ability to tolerate dehydration, but has failed to elucidate the specific role played by trehalose. By using Fourier transform infrared spectroscopy we measured the transition temperature of phospholipids in both intact S. cerevisiae and isolated plasma membranes dried in the presence and absence of trehalose. Our results show that trehalose lowers the temperature of the dry gel to liquid crystal phase transition in yeast from around 60 degrees C to about 40 degrees C, thus allowing yeast rehydrated above 40 degrees C to avoid the damaging effects of passing through a phase transition. These results explain both the need for trehalose and the observation that yeast must be rehydrated with warm water if they are to remain viable. Only when trehalose is present is the dry transition within a physiologically tolerable range and only when the cells are rehydrated above 40 degrees C will they avoid passing through a phase transition.

This supports that trehulose is a protectant in thermal stress and dessication rather than osmotic stresses.



Okay, okay, if you're still with me, here's why I posted all this. It seems that after this recent discussion, it seems that the only reason left (aside from cost and ease, of course) to favor rehydrated dry yeast over a dry yeast starter is the high levels of trehulose to protect against the osmotic stress of a hypertonic wort solution. However, it doesn't appear that this is even a benefit of having a high trehulose content.

 

[boydster]

Ok. So while I digest what you just posted... I just want to mention that none of it still offers any reason to believe that you'll have healthier yeast by making a starter, which is what you were driving at. So essentially, it's more work for no reward. Unless, of course, it is unreasonable for you to make it to the LHBS to purchase an extra packet of yeast before brew day and you need more cells than you have in the packet. But again, it isn't making the yeast healthier. Further, when is the yeast most susceptible to a thermal shock? For me, at least, it's during the first few days of fermentation when the yeast is most active. Having a backup plan is key. If my fermentation temperature control isn't perfect, the trehalose reserve seems like it might help with a little bit of extra protection from thermal shock? I guess that's what I want to review your links for, but I still just don't see how one would think the starter would result in healthier yeast like you were postulating earlier. Nothing I have seen would indicate that.

 

[max384]

Ok. So while I digest what you just posted... I just want to mention that none of it still offers any reason to believe that you'll have healthier yeast by making a starter, which is what you were driving at. So essentially, it's more work for no reward. Unless, of course, it is unreasonable for you to make it to the LHBS to purchase an extra packet of yeast before brew day and you need more cells than you have in the packet. But again, it isn't making the yeast healthier. Further, when is the yeast most susceptible to a thermal shock? For me, at least, it's during the first few days of fermentation when the yeast is most active. Having a backup plan is key. If my fermentation temperature control isn't perfect, the trehalose reserve seems like it might help with a little bit of extra protection from thermal shock? I guess that's what I want to review your links for, but I still just don't see how one would think the starter would result in healthier yeast like you were postulating earlier. Nothing I have seen would indicate that.

I've read it all over the place, on this site, heard it from both of my LHBS owners. I hear all the time that liquid yeast is better than dry, and that liquid is best when made into a starter, thus a starter is better than dry. I guess I've always had it in my head that liquid is better than dry. It also makes sense to me that a slurry of active yeast would be less stressed than a slurry of recently rehydrated yeast when put into the wort.

 

[flars]

This ferment went great. I've since repitched the slurry. It's going even better. I see no reason not to make a starter with dry yeast. I've posted on this because internet searches don't give much info.just a lot of "don't do it". Well,I did it.I'm just crazy like that.lol

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Trying to find basic information on whether or not you could make a starter with dry yeast was always frustrating. The usual liturgy was you can't make a starter with dry yeast because dry yeast is so cheap. One has nothing to do with the other.
Yes, you can make a starter with dry yeast. Lallemand site has some good technical articles on starters with dry yeast.
There is also an article on harvesting, storing, and re-pitching cold.

Thanks for starting this thread.

 

[boydster]

I've read it all over the place, on this site, heard it from both of my LHBS owners. I hear all the time that liquid yeast is better than dry, and that liquid is best when made into a starter, thus a starter is better than dry. I guess I've always had it in my head that liquid is better than dry. It also makes sense to me that a slurry of active yeast would be less stressed than a slurry of recently rehydrated yeast when put into the wort.

I understand that is your gut feeling, but I don't see anything to back it up and my own experience doesn't back it up. The "liquid yeast is better than dry, and that liquid is best when made into a starter, thus a starter is better than dry" statement is drawing a false equivalence between the benefits of using liquid yeast vs dry and making a dry yeast starter vs rehydrating. Saying liquid is better than dry is an opinion, and is wholly unrelated to whether or not you make a starter. Dry yeast is incredibly healthy if you rehydrate it properly. Making a starter wouldn't improve the vitality.

 

[cjgenever]

Boydster and max384,
You guys are both bringing up great points. I feel like we're grabbing at straws here and going back and forth with two slightly different real world situations in mind. In the situation that I was in the starter was well thought out and actually became part of the recipe.

Ferm temps were low for a starter to make good beer. I did temper it with the wort to help prep the yeast for the higher gravity. I am doubtful the temper was long enough to help. I seemed to have happy yeast and I certainly pitched enough cells because fermentation took off like a fresh slurry pitch.

That said, I think this thread has been a complete success. We have actually touched on the biology of what is going on. I am not convinced that a dry yeast starter is somehow less effective than a slant starter, cell counts being the same. I am totally convinced that dry yeast is best prepared to be pitched immediately after rehydration, but I think we have all been in agreement on that anyway. The argument has been on how truly detrimental a dry yeast starter is. I think this is where the disconnect is. The two arguments are so closely related that it is difficult to see that we are arguing about two different things, which makes seeing eye to eye difficult.

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[cjgenever]

We steeped it and got the same result!

The drying process is too stressful for many strains. 1096 is known to be cleaner than us-05, even though they are the same strain. This is because of the stresses out undergoes drying. As the process has been refined it has become less stressful to the yeast. This is why there are so many more dry yeasts available now as opposed to fifteen years ago. I don't think either is better.they both have a place at both the home and pro level. I like the extra control I feel I have with a slant, but often end up with a packet because that's what they have at my preferred lhbs. The more pronounced esters of us-05 are less of a problem with fine temp control.

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[sandyeggoxj]

The drying process is too stressful for many strains. 1096 is known to be cleaner than us-05, even though they are the same strain. This is because of the stresses out undergoes drying. As the process has been refined it has become less stressful to the yeast. This is why there are so many more dry yeasts available now as opposed to fifteen years ago. I don't think either is better.they both have a place at both the home and pro level. I like the extra control I feel I have with a slant, but often end up with a packet because that's what they have at my preferred lhbs. The more pronounced esters of us-05 are less of a problem with fine temp control.

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You mean 1056, right? Wyeast American Ale? Just wondering.

 

[cjgenever]

I'm out for a while. I need to reread these articles and take notes. Then I'll hit Google scholar.

FWIW, I was going to buy the yeast book last week, but the reviews turned me off to the idea. I expected it to dive into the biology at least a bit and talk about what we are talking about here. The reviews led me to believe that it was simply an organized reiteration of brew strong conversations between Zainasheff, White, and Palmer. I think I have those podcasts memorized by now. haha

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[cjgenever]

There is a yeast textbook for biomedical students with its own complimentary website on Amazon. $70 is nothing for a textbook.I'm going to look into it further. I've begun pricing decent microscopes, looks like ~$200. Looks like a yeast project will need to compete with a powdercoating setup for my motorcycle projects this summer. Hmmmm... decisions, decisions.

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[max384]

I understand that is your gut feeling, but I don't see anything to back it up and my own experience doesn't back it up. The "liquid yeast is better than dry, and that liquid is best when made into a starter, thus a starter is better than dry" statement is drawing a false equivalence between the benefits of using liquid yeast vs dry and making a dry yeast starter vs rehydrating. Saying liquid is better than dry is an opinion, and is wholly unrelated to whether or not you make a starter. Dry yeast is incredibly healthy if you rehydrate it properly. Making a starter wouldn't improve the vitality.

It seems after Googling that most of the 'liquid is better than dry' opinions are outdated with modern dry yeast techniques. So, I guess a lot of that still sticks around, it seems.

But why wouldn't making a starter improve the vitality of the yeast, if they're pitched in the wort when they're much more active?

 

[cjgenever]

What cause would the yeast have for depleting the trehalose? The glycogen has more of a reason to be depleted. Read the link I posted earlier. I ask the question earnestly, but I don't expect that you have the answer. Maybe someone else does though?

Sorry,I missed that. I was referring to the glycogen. I must admit, I now have a better understanding of the specific reserves in the cell thanks to your link! They are using the glycogen for food rather than building sterols and unsaturated fatty acids which are needed for cell wall construction during budding. That's the point being the olive oil thing, one less fatty acid to produce.

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[cjgenever]

You mean 1056, right? Wyeast American Ale? Just wondering.

Yeah,1056. Sorry, I'm on a phone here

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[IslandLizard]

Has anyone actually counted the (live) cells in a package of Fermentis yeast, with proper hydration. And then again half an hour to an hour after pitching?

From the US-05 product sheet (2012):
Viable cells at packaging: > 6 x 10^9/g
Package size 11.5g
Total cells per package > 69 billion

I know most literature (e.g., Palmer) refers to around 200 billion cells, and maybe that was or is correct or just the consensus, but 69 billion is only a bit more than a third. Is the actual count way understated? Mr.Malty thinks so (around 190 billion).

In comparison, a smack pack of WYeast claims to contain 100 billion cells. Even after 1 month of storage in the fridge it has 75 billion left, which is likely conservative. Pitching a single smack pack in 5 gallons of wort is rarely recommended, yet it contains as many cells as a sachet of dry, according to Fermentis.

The only thing I can think of where that 200 billion is coming from is that the dry yeast, when properly hydrated goes through a quick growth phase and doubles or triples the cell count at or right after pitching time.

Anyone?

 

[boydster]

Sean Terrill did, using US-05. Also Fermentis claims that the number on the packet is it guaranteed minimum (think: packet that is about to expire and has been stored at room temp) and that each packet contains roughly 150 billion live cells when it's packaged.

 

[cjgenever]

Zainasheff claims to have counted many times. He states 220bil/11.5g. Kaiser is a major voice in questioning these numbers as Zainasheff had never released any documentation on these tests.

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[boydster]

Right, but keep in mind Zainasheff isn't the only one who uses that estimate of roughly 20 billion per gram. Clayton Cone quotes that figure. Kaiser also mentions the same figure with dried WY2042 as recently as July 2013 (http://braukaiser.com/blog/blog/2013/07/01/yeast-growth-in-hopped-wort/ read the first paragraph under the "Growth Yield Over IBU" chart). I think the question becomes: how many of those dry cells are still alive after rehydrating. The answer to that depends heavily on the conditions of the hydration, but Clayton Cone says the same thing as CW & JZ - that it is possible to restore 100% viability if you of the viable cells with proper rehydration. How many of us accomplish that? Probably few, if any.

 

[cjgenever]

Thanks. I find it difficult to find what I'm looking for in kais' research via his site. Probably because I use the phone for everything. I find out hour or miss. I have found things on his site through Google that I couldn't find on the site via the site :-(

I don't dispute these numbers. In fact, I base my pitch on them.

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[cjgenever]

Boydster,

Speaking of kai, did you see his research on gravity in starters. I think it has bearing on some of the biology we've touched on. He shows that at 20 Plato the reproduction rate is lessened, but still substantial when compared to the more common starter gravity of 10 Plato. However, it seems that the trehalose would be increased in the cell due to the higher concentrations of sugar. If this is the case, and this trehalose is so important to the pitch, should we be considering higher starter gravities for really big beers to reduce osmotic stress?

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