Yeast immobilization: magic beans of fermentation

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Warthaug said:
But now you're talking about a completely different thing. To get ester production (either to make lipids or to make flavour compounds) you need the yeast to make the precursors, which is an aerobic process. Cell division is not required - but its also hard to put yeast into an aerobic state, along with everything else they need to make precursors, without having them divide. Your bead system may be an exception to that - there is no (biochemical) reason why you shouldn't get proper ester production, and you should be able to generate precursors (without cell divisions) by exposing the yeast to aerobic conditions - i.e. by oxygenating your wort.
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First of all, I <3 this thread all the more for all the great tangential scientific discussion that is coming out of it. I am learning a lot from it.

Given what you are saying - that oxygenation is important to ester formation and is also needed for yeast growth - would it be possible to eliminate ester formation by 1) not oxygenating my wort and 2) massively over-pitching to compensate for the poor oxygenation's effect on yeast growth? What would be the side effects of that? Obviously my goal is to eliminate ester production without having to keep such a close eye on ferm temperatures (which is difficult for me without investing a lot of money in equipment or labor)
 
MalFet said:
Considering that this is what I said originally, I think what's confusing (at least to me) is that it's not clear exactly what you're objecting to.
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I had miss read your original (I've just reread it) - I had understood it comparing same mass object to same mass object and differing shapes. This is vastly different than being able to make smaller massed objects. Additionally I suspect that time is more valuable than surface area, but that is just me.

I appologize for the confussion (which started with me.)
 
A totally different question which I don't recall being mentioned.

If the 'magic beans' hold all the yeast, what suggestions are there for carbonation? Yeah I know keg, and pitch new yeast? That is pretty much it isn't it?
 
ACbrewer said:
A totally different question which I don't recall being mentioned.

If the 'magic beans' hold all the yeast, what suggestions are there for carbonation? Yeah I know keg, and pitch new yeast? That is pretty much it isn't it?
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I suspect you may get some 'escapees' from the surface but how many? I would not back sweeten with something fermentable and assume there would be no further fermentation, especially if bottling.
 
ACbrewer said:
I had miss read your original (I've just reread it) - I had understood it comparing same mass object to same mass object and differing shapes. This is vastly different than being able to make smaller massed objects. Additionally I suspect that time is more valuable than surface area, but that is just me.

I appologize for the confussion (which started with me.)
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No worries man, I can see how it might have been unclear. :mug:

ACbrewer said:
A totally different question which I don't recall being mentioned.

If the 'magic beans' hold all the yeast, what suggestions are there for carbonation? Yeah I know keg, and pitch new yeast? That is pretty much it isn't it?
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Honestly, I have no idea. I was just about to post about an interesting turn of events related to that question here.
 
<QUOTE>It is a really curious phenomenon. The yeast are trapped in a ball of calcium alginate, but still perform fermentation of sugars.</QUOTE>

I believe there's a theory on cancer cells that similar to this concept. The Warburg Hypothesis. I don't think your yeast balls are anaerobic however.
 
Strange twist!

I promised a photo to MrNatural yesterday and failed to post one. I got home late and checked the beer, which in all honestly looked exactly the same as it did the day I pitched. This morning, still exactly the same.

At lunch, I swang by the house to get something I had forgotten, and by then the bead-batch had thrown a krausen! I'm not completely sure what to make of it. There can't have been much fermentable sugar left by this point...my corrected refractometer reading put me at about 1.020 (+/- a few points).

As far as I can think, there are two possibilities: 1) I picked up something wild, or 2) yeast on the surface budded off and colonized the batch free-range style. Nothing notable about smell, though perhaps I'll know more once I crash and taste. The beer is cloudier than it was this morning, but still quite a bit clearer than the control batch.

I play to carry the beads forward to a few more batches, and I'll be very interested to see if this happens next time.

photo-59463.jpg

(Sorry for the rotated image...I'll fix it later.)
 
MalFet said:
@Warthaug - Interesting discussion, but this has gotten more detail-driven than is germane to this context.
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hardly the first time a HBT thread went off topic; IME, usually the best discussions start this way... :drunk:

MalFet said:
I'll admit that I remain skeptical about your explanations in significant part because you speak with a great deal more certainty about the role or non-role of esters than anything I've seen in the primary literature.
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But which primary literature? Brewing vs. biochemical? They are quite different. Like I said in my last post, the processes which create esters are (partially) oxygen dependent. In the brewing world oxygen dependent processes are almost impossible to separate from cell division. Its much less of an issue in the biochemical literature where work is done under more controlled conditions.

And I'd point out again that we are talking about two things; I never said cell division (or, at least, the processes that occur concurrently; not necessarily due to the division process itself) were not required for ester production - indeed, I pointed out repeatedly that precuror production is an oxidative process that typically occurs at the same time as cell division. I was addressing the 'myth' that ester production itself occurs at this time - it doesn't (at least, not to any significant extent). Ester production occurs after cell division has largely ceased and anaerobic fermentation has begun. These conditions are required to a) provide the ethanol used in the esterfication process, b) activate the expression of the esterfication genes, and c) ensure a large enough pool of acetyl-CoA for these reactions to progress.

MalFet said:
I have no doubt that it is very complicated, and you are necessarily correct that anything said on a beer forum will be an oversimplification. But, time and again I've seen the peer-reviewed claim that yeast reproduction is necessary for a "normal" ester profile. Perhaps there are ways around that, but in the normal course of things the link that people around here establish between population growth and flavor profiles seems to be a reasonable translation from the scientific literature.
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In my experience, translation from scientific (at least, biochemical/genetic literature) to brewing is poor. And while I try to be nice, the brewing literature generally sucks (as in, is of poor scientific quality).

MalFet said:
I'd love to learn that yeast immobilized in alginate (hardly my process) are an exception to this, but that seems unlikely. In fact, every technical description I've seen on alginate fermentations list as the primary downside the poor ester profile caused by the lack of yeast reproduction. If there's a way around this problem, that could salvage the technique, but so far at least it seems that the big money players at AB-InBev and SABMiller haven't yet found it.
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I'd counter this by saying:
1) In my (limited) reading no one has tried to alter ester profiles through controlling oxygen concentrations, etc, and
2) I don't see the big brewers having much interest in this method, simply because it doesn't simplify things for them. They would still have to filter for cold break and any yeast that escaped the beads, plus this appears to slow fermentation, so there is little incentive to add the extra steps of generating the beads & recovering them later. As a homebrewer I'm intrigued, but I don't see much of a commercial upside to this.

Bryan
 
chocotaco said:
Given what you are saying - that oxygenation is important to ester formation and is also needed for yeast growth - would it be possible to eliminate ester formation by 1) not oxygenating my wort and 2) massively over-pitching to compensate for the poor oxygenation's effect on yeast growth? What would be the side effects of that?
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Typically high pitch rates reduce esters, but I'd be wary of not oxygenating; while the main reason for oxygen is to get some cell division, it does have an impact on non-ester flavour compounds. I think (but am not sure) that less O2 can create more phenolics or higher alcohols (I forget which).

Bryan
 
MalFet said:
2) yeast on the surface budded off and colonized the batch free-range style.

The beer is cloudier than it was this morning, but still quite a bit clearer than the control batch.
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This is my guess, especially based on the cloudiness. Poor sanitation would probably show up later and slower.
 
MalFet said:
As far as I can think, there are two possibilities: 1) I picked up something wild, or 2) yeast on the surface budded off and colonized the batch free-range style.
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This brings up an interesting point - I'm not hypothesizing that you have contamination, but if the yeast aren't propagating throughout the wort, then they won't have an opportunity to "crowd out" other critters that might have slipped through the cracks. Perfect sanitation would be even more critical.
 
Hermit said:
This is my guess, especially based on the cloudiness. Poor sanitation would probably show up later and slower.
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I would agree. So if the yeast is indeed budding off is there a point to immobilization? other than a degree clearer beer?
 
chocotaco said:
This brings up an interesting point - I'm not hypothesizing that you have contamination, but if the yeast aren't propagating throughout the wort, then they won't have an opportunity to "crowd out" other critters that might have slipped through the cracks. Perfect sanitation would be even more critical.
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the yeast are still using up a large portion of the available nutrition as well as producing alcohol so I'm not sure if crowding out would matter.
 
Warthaug said:
1) In my (limited) reading no one has tried to alter ester profiles through controlling oxygen concentrations, etc
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You should read more broadly then. ;)

This relationship is extensively explored in the brewing literature, and virtually every review article discusses the experimental findings. See, for example, "Control of Ester Synthesis During Brewery Fermentation" (Smart 2008).

I understand that it is a great deal of fun for the basic research guys to denigrate the applied research guys (and I'm sure I'm guilty of it in my day job), but ultimately the purpose here is to brew better beer, right? If you're actually trying to do something, the basic science literature is generally incredibly frustrating. To that end, I'm not sure what good comes from separating oxygen-dependent processes from cell division if, as you say, "in the brewing world oxygen dependent processes are almost impossible to separate from cell division".

If there's an upshot here for beer brewing rather than explorations in metabolism, I'd love to hear it. Sincerely. I must admit, though, I'm having a very hard time extracting a tangible punchline from the distinctions you're carving. :mug:
 
MalFet said:
I understand that it is a great deal of fun for the basic research guys to denigrate the applied research guys (and I'm sure I'm guilty of it in my day job), but ultimately the purpose here is to brew better beer, right? If you're actually trying to do something, the basic science literature is generally incredibly frustrating.
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I don't think I denigrated anyone; as I said, I try to be nice. But by the standards of most bio fields, the commercial fermentation literature is sub-par.

I've found the basic literature to be very useful for some of my wild yeast and "custom-strain" stuff; I guess 'useful' is in the eye of the beholder.

MalFet said:
To that end, I'm not sure what good comes from separating oxygen-dependent processes from cell division if, as you say, "in the brewing world oxygen dependent processes are almost impossible to separate from cell division".
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Well, in your experiment it may be possible to do just that - its an exciting prospect (at least, it is to me). But going back to my OP, it again is consistent with esters not being produced during the aerobic/cell division portion of the ferment.


MalFet said:
If there's an upshot here for beer brewing rather than explorations in metabolism, I'd love to hear it. Sincerely. I must admit, though, I'm having a very hard time extracting a tangible punchline from the distinctions you're carving. :mug:
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Well, firstly I did start my posts in reply to a metabolism question, so the direction of the conversation makes sense (at least, it does to me).

The upshot for brewing could be more control over the final product - being able to separate flavour production from other aerobic processes (which your beads may be able to do) would give us a great deal more control.

Bryan

EDIT: unless I'm mis-reading, the paper you cited didn't look at yeast in beads, but rather just at ester production in general.
 
I agree, this conversation y'all are having has provided me with a great deal of information using language that I (a layperson) can mostly follow. I don't think it's tangential at all. In fact I think it is highly relevant to the questions at hand. Not to mention highly entertaining! And it gives us something to do until the Mupor guys get back from TX and start posting again!
 
Update!

When I got home yesterday, the mysterious krausen had already dropped and the beer was bright again. There's not much sediment in the bead sample jar (especially compared to the control sample), so if renegade yeast broke free from their containment and attempted to repopulate, it was a short-lived rebellion.

I know it's still early, but I couldn't resist the temptation to pull a few samples to taste. I took a bit of each beer and crashed them in the fridge for ~24 hours. They've both reached equivalent (presumably terminal) gravities and they are identical in color. I had my lady friend pour a triangle test and I let them warm up to the low 50s. I don't have a great palate, but the difference was very significant. Here are my notes:

Beer B, C: still quite green, significant acetaldehyde; very "British", with fruit tones (apples, grapes) and sweetness. Muddled and harsh hop bitterness.
Beer A: Very, very clean. Not quite bland, but rather thin mouthfeel. Hops punch through, stay neutral. Grain.

As I later discovered, B&C were the control and A was the bead-beer. At this point, I don't think there's much of a conclusion to draw, since the control beer still tastes so young. For example, I don't know if it's the bead-beer that's thin or if it's just the recipe's thin and the control beer doesn't come across that way yet.

What's most striking, though, is that the bead beer tastes like a *finished* beer even though it's just five days old. It's not a great beer, but nor is it a terrible one. Then again, this wasn't a recipe for a great beer. I'm pleasantly surprised, at least to the point where I intend to keep experimenting.

:mug:
 
Alright, just for you passedpawn:

This isn't the beer, but I made up another batch of the beads to test a notion I had that didn't end up going anywhere. So, I mixed up a 15 Brix sugar solution about four days ago to test out some other properties of the beads. My refractometer now reads 5 Brix, though I have no sense whatsoever of whether or not that's done. The small streak next to the '4' in the second picture is a bubble floating up.

There's very little sediment here as you can see, and the sugar water has remained clear throughout. For what it's worth, it now tastes exactly like Duncan Hines vanilla cake mix.

photo1-59468.jpg

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I wonder if the tiny sediments and krausen would disappear from later batches as the "outside" or surface yeast lose the ability to reproduce (if they had any) any any loose pieces are washed from the beads.
 
Hermit said:
B&C 'yeast bite' flavor maybe?
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Depends what you mean. I don't think I'm tasting yeast in suspension, but certainly there's a lot that still needs to breakdown further and drop out.

fizgig said:
I wonder if the tiny sediments and krausen would disappear from later batches as the "outside" or surface yeast lose the ability to reproduce (if they had any) any any loose pieces are washed from the beads.
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That's actually what I've been speculating. I didn't rinse the beads particularly well after I made them for the beer batch, though I did for the sugar water batch. It could be that that made the difference.
 
Wow! Very interesting results. Thank you for your updates, MalFet. You're doing the nerdy work for those of us who can't get the time. I vote for you as rad researcher homebrewer of the year!
Rad thread. Rad experiment. Keep up the good work!
 
MalFet said:
Beer B, C: still quite green, significant acetaldehyde; very "British", with fruit tones (apples, grapes) and sweetness. Muddled and harsh hop bitterness.
Beer A: Very, very clean. Not quite bland, but rather thin mouthfeel. Hops punch through, stay neutral. Grain.
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Beer A is quite possibly like that due entirely to the lack of carbonation. Hopefully you'll still have enough by the end of this to do a similar tasting with carbonated samples.

I mentioned early in the MuPor thread that the ester profile would probably be nonexistent. Despite several parties insisting that this wouldn't be an issue (for various reasons), it just didn't seem possible for yeast with totally (or almost totally) inhibited reproduction to produce a "normal" ester profile, so it shouldn't really be much of a surprise (nor is it). However, even though it validates what I (and others, including yourself) have said, I'm not quite ready to call it confirmed just yet, based solely on a single tasting. Obviously there needs to be a number of samples, preferably using very different types of yeast. I think at the very l least there ought to be an extreme-ester Belgian bubblegum strain, which should be (separately) fermented at both high AND low temperatures.

Still, that's only a huge problem for certain beer styles. At this point, I'm not really seeing much of a downside with neutral beers, and most wines and other fermented beverages (yet). To me, wine in particular seems like a great potential use for this, especially since it's (usually) not carbonated, and because yeast sediment generally isn't tolerated in wine nearly as much as it's tolerated in beer. Not to mention that it could have great implications for backsweetening by hobbyists. Of course, this depends on whether or not enough yeast is left behind to restart fermentation (see last paragraph).

MalFet said:
That's actually what I've been speculating. I didn't rinse the beads particularly well after I made them for the beer batch, though I did for the sugar water batch. It could be that that made the difference.
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Doubt it. The sugar water obviously just doesn't have break material. I wouldn't expect it at all to have sediment nor even a krausen regardless.

One experiment that would be very worthwhile though would be to test if enough yeast "falls off" (or whatever) to meaningfully ferment, determining if simply removing the beads is a viable alternative to pasteurization in a more conclusive manner than just a visual assessment of the sediment. Basically, just ferment a batch, remove the beads, and then add more fermentable sugars (as a boiled or even sterilized solution, if possible). Needless to say, it needs to be given much more time in order to distinguish between a non-fermenting sample and a sample that is merely fermenting slowly. If it appears that it DOES still ferment, the same experiment should be carried out with the exact same beads several more times (minimum), in order to rule out not only accidental infection, but also to take into account the possibility that any yeast present might have merely "washed off" from the outside of the beads.
 
The risk of bottle bombs when using live yeast is just too big a threat at this point and could take YEARS to fully resolve by experiment by the home brewer. At what point are you comfortable giving a bottle to someone?
 
Hermit said:
The risk of bottle bombs when using live yeast is just too big a threat at this point and could take YEARS to fully resolve by experiment by the home brewer. At what point are you comfortable giving a bottle to someone?
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Hmm...interesting. Why do you think there's more of a risk with the beads than with regular yeast?
 
MalFet said:
Hmm...interesting. Why do you think there's more of a risk with the beads than with regular yeast?
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I guess I didn't write my post well enough to continue the train of thought. My concern was when he mentioned "back sweetening". If you have a few live cells they might take a very long time to reproduce enough 'bud'dies to consume all of the sugar.
 
Hermit said:
I guess I didn't write my post well enough to continue the train of thought. My concern was when he mentioned "back sweetening". If you have a few live cells they might take a very long time to reproduce enough 'bud'dies to consume all of the sugar.
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Oh right. That's definitely true. I strongly suspect that there is yeast in suspension even under ideal circumstances. The no-pasteurize thing is a very cool idea and fully worth exploring, but I'm skeptical that it will work.
 
Hermit said:
The risk of bottle bombs when using live yeast is just too big a threat at this point and could take YEARS to fully resolve by experiment by the home brewer. At what point are you comfortable giving a bottle to someone?
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I'm not sure. I'd probably start with a month using plenty of fermentables in a test (ie not with bottles). If I were to do it myself, I'd do a few other samples alongside it, maybe using (for example) a single "grain" of dry yeast, perhaps a couple more with the "pitch" increasing by an order of magnitude each time, and maybe even from the tip of an inoculating loop using plating technique to reduce it to a "single" cell. Then I could see how long those take to get a sense of how long I need to wait for the un-beaded sample. I'd most likely do all these experiments at a slightly elevated temperature, probably in the 80°-100° range.

And of course, a control - if nothing else, just as some extra assurance that my process is adequately sanitary, to help rule out fermentation as a fluke.

I might even put a small sample (safely) away for an extended period of time, perhaps several years, just for added confidence, though I'd feel more than comfortable enough if the experiment resulted in no change detected after a month.

I moved last year and still haven't finished putting together a new electric brewery in my new place, so I haven't brewed here even once yet. Otherwise I'd just go ahead and do all these things instead of talking about it. :D
 
Have your think about using a reverse spherification technique instead of what your using? in molecular gastronomy the direct spherefication it´s made just like you did but with the reverse technique the membrane it´s a lot less thick, basicly what you do is add a little calcium (if your base ingrediente has not already haves calcium) and put it in an alginate bath, you do it the other way around. I do this with my spheric mozzarella, the difference is that when you use the direct method, with the caviar for instance, the little beads keep hardenind even after you take them aout of the calcium bath, with the indirect method it stops soon as you remove the bead from the alginate.
 
Obliviousbrew said:
Have your think about using a reverse spherification technique instead of what your using? in molecular gastronomy the direct spherefication it´s made just like you did but with the reverse technique the membrane it´s a lot less thick, basicly what you do is add a little calcium (if your base ingrediente has not already haves calcium) and put it in an alginate bath, you do it the other way around. I do this with my spheric mozzarella, the difference is that when you use the direct method, with the caviar for instance, the little beads keep hardenind even after you take them aout of the calcium bath, with the indirect method it stops soon as you remove the bead from the alginate.
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So your point would be to produce a softer or more porous bead?
 
Interesting prospect. I'm not actualy convinced that permeability is the limiting factor so much as plain old stratification. But, I haven't yet figured out an easy way to test this. On my next batch, I've considered using a stirplate throughout.
 

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