Happy to. Here you go. The article addresses this most directly toward the end, and cites supporting clinical studies and medical journals. Enjoy.
http://articles.mercola.com/sites/articles/archive/2011/09/20/salt-myth.aspx
I think common practice is over feeding our little ones!
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http://articles.mercola.com/sites/articles/archive/2011/09/20/salt-myth.aspx
Unfortunately, those sources don't back up the claim that sea salt is good for you. I few doctors promoting sea salt is not enough. Good science is hard come by. I guess that is the crux with this whole thread.
Perhaps that statement is taken out of context. At the risk of sounding like a nit-picking ninny, do the folks as Scott Lab realize that glutamate IS an amino acid?
Scott Labs handbook is at its heart, a marketing tool, not a scholarly work on fermentation. Dare I say it? - take it with a grain of SALT!:laughing11::laughing3::laughing7::laughing7::laughing9:
Today I started reading about Fermaid O again. I stumbled on this thread which speaks of a 'winery supplier brochure'. The important part for me was this:
"Apperently too much (initial nutrients) can make the yeast overpopulate and make them go through a die out phase as they try and reach equalibrium... also i thinj it said it can also lead to too rapid of a fermentation causing a loss of delicate.aromatics...... this is if i remembered correctly" (http://www.winemakingtalk.com/forum/showthread.php?t=38628&page=2)
This information seems to coincide with what mazers have been reporting on these forums. When people do not follow Tosna to the dot they run into problems. One of these causes *could* be that they are front loading nutrients or making just 2 additions. It is not merely the case of whether or not you have the correct total amount of nutrients, but what type of nutrients and the timing also seems to be important. With an overpopulation of yeast I think it's possible that the yeast need a larger overall nitrogen amount, at least if you want to avoid this die out phase and possible sulphur smells from stressed yeast (at worst a stuck fermentation?).
Tosna splits nutrient additions into 4 parts. This means that the initial addition is much smaller than just splitting additions in two like is common practice on these forums. This results in a more controlled growth phase and avoiding the problem mentioned above. Moreover, Fermaid O seems to be gradually consumed by yeast since, as seen from various studies, Fermaid O provides smaller 'spikes' in fermentation. These all point towards yeast not overpopulating. Of course, this cannot be confirmed without making a cell count estimation in a lab environment.
The second part of the comment also coincides with mazers claiming that Fermaid O and the tosna approach results in better aromatics.
Unfortunately, I cannot locate the document referred to in that thread, although I am confident that another study which shows this could be found since it is not directly related to Fermaid O or tosna
"Apperently too much (initial nutrients) can make the yeast overpopulate and make them go through a die out phase as they try and reach equalibrium... also i thinj it said it can also lead to too rapid of a fermentation causing a loss of delicate.aromatics...... this is if i remembered correctly" (http://www.winemakingtalk.com/forum/showthread.php?t=38628&page=2)
This information seems to coincide with what mazers have been reporting on these forums. When people do not follow Tosna to the dot they run into problems. One of these causes *could* be that they are front loading nutrients or making just 2 additions. It is not merely the case of whether or not you have the correct total amount of nutrients, but what type of nutrients and the timing also seems to be important. With an overpopulation of yeast I think it's possible that the yeast need a larger overall nitrogen amount, at least if you want to avoid this die out phase and possible sulphur smells from stressed yeast (at worst a stuck fermentation?).
Tosna splits nutrient additions into 4 parts. This means that the initial addition is much smaller than just splitting additions in two like is common practice on these forums. This results in a more controlled growth phase and avoiding the problem mentioned above. Moreover, Fermaid O seems to be gradually consumed by yeast since, as seen from various studies, Fermaid O provides smaller 'spikes' in fermentation. These all point towards yeast not overpopulating. Of course, this cannot be confirmed without making a cell count estimation in a lab environment.
The second part of the comment also coincides with mazers claiming that Fermaid O and the tosna approach results in better aromatics.
Unfortunately, I cannot locate the document referred to in that thread, although I am confident that another study which shows this could be found since it is not directly related to Fermaid O or tosna
I often think that things are taken as "truth" too often on the web. Just because one/some guy says this or that isn't enough for me to count on it without trying to find supporting evidence. Even then it could still end up being false. Not all truths are true. "The world is flat" on and on!
I find the "overpopulate" line would make me have a string need to find scientific proof. That really sounds like something a layman would say and others would grab onto a truth. Same with the aromatics piece. Can't find it/can't remember if I remember it correctly.
I find the "overpopulate" line would make me have a string need to find scientific proof. That really sounds like something a layman would say and others would grab onto a truth. Same with the aromatics piece. Can't find it/can't remember if I remember it correctly.
Fair enough squatchy. This is why in the end I said that it's a pity I couldn't find the document they were referring to.
What I did was share the thread, posit a theory, and in the end I said I think it is possible for us to find a study which supports this.
I think the aromatics part makes plenty of sense. At least on these forums I have heard multiple times that people believe that aromatics can be blown off by a vigorous fermentation. Maybe we need to find a study which supports aromatics vs ferment vigor, but then why did people accept this as true before and not now?
I also thinks it makes perfect sense that yeast will multiply during the growth phase according to available nutrients. It is surely possible that yeast will not multiply as much if no nutrients are available at all. This means that up to a certain point at least cell multiplication during the growth phase is directly proportional to nutrients available. Now we do not know whether front loading or dividing the dose by 4 would make such a difference. We also do not know if this dieing out phase is true.
I thought I made it clear that i wasn't absolutely sure this is fact. Heck even with scientific studies we cannot be sure. People make fake/erroneous studies all the time. people focus on one thing over another in studies all the time, while one study might say the overpopulation is good because of w and x, another could say it is bad because of y and z and we would never know which is the best approach. We couldn't even agree whether or not overpitching yeast is good or bad where it was clear that one would lead to overpopulation and the other would not, and even though there were clear pros and cons attested to each practice
What I did was share the thread, posit a theory, and in the end I said I think it is possible for us to find a study which supports this.
I think the aromatics part makes plenty of sense. At least on these forums I have heard multiple times that people believe that aromatics can be blown off by a vigorous fermentation. Maybe we need to find a study which supports aromatics vs ferment vigor, but then why did people accept this as true before and not now?
I also thinks it makes perfect sense that yeast will multiply during the growth phase according to available nutrients. It is surely possible that yeast will not multiply as much if no nutrients are available at all. This means that up to a certain point at least cell multiplication during the growth phase is directly proportional to nutrients available. Now we do not know whether front loading or dividing the dose by 4 would make such a difference. We also do not know if this dieing out phase is true.
I thought I made it clear that i wasn't absolutely sure this is fact. Heck even with scientific studies we cannot be sure. People make fake/erroneous studies all the time. people focus on one thing over another in studies all the time, while one study might say the overpopulation is good because of w and x, another could say it is bad because of y and z and we would never know which is the best approach. We couldn't even agree whether or not overpitching yeast is good or bad where it was clear that one would lead to overpopulation and the other would not, and even though there were clear pros and cons attested to each practice
OK, finally found a document similar to the one they were referring to. This is the same type of catalog (I think) but from a much later date, which should be better.
Info I found which supports my theory just from what I read in BSG catalog http://bsgwine.com/PDF/1.12.16_2016 BSG Wine Catalog PROOF.pdf
"Insufficient nitrogen has many negative effects on yeast growth and metabolism. Cell numbers, fermentation rate, protein synthesis (including the glucose transport proteins that bring sugar into the cell), and alcohol resistance all depend on the availability of nitrogen at the right time." (pg 10)
"DAP has been called ‘yeast candy’ because yeasts use ammonia so easily. They deplete the supply during growth phase and very early fermentation. The more ammonia that is present early, when yeasts are growing, the more cells are produced (“biomass”), all of which continue to need nitrogen throughout fermentation. A large biomassmay run out of nitrogen early." (pg. 19)
Does this say that a large initial addition will starve yeast later on?
"Despite the inconvenience, we recommend making multiple additions of products in which the nutrients are immediately available and do not have to leak out of partly autolyzed cells or dissolve slowly. Immediate availability gives much better control, allowing the winemaker to respond to fermentation kinetics by adjusting amounts and timing of the additions. A large influx of nitrogen as DAP throws the cell’s metabolism off balance, potentially leading to overgrowth of yeasts, runaway fermentation, flavor problems, nitrogen wasting, and leftover amino acids." (pg. 20)
A refernce to the overgrowth theory?
"Too much DAP, especially at the beginning, can prevent use of some amino acids: arginine, in particular. Leftover arginine is an ethyl carbamate
precursor, and can feed spoilage microbes like Brettanomyces and Lactobacillus. Amino acids are also aroma and flavor precursors necessary for the wine’s sensory profile. Adjust nutrient supplement timing so that the yeasts “eat their amino acids” instead of “spoiling their dinner” by gorging on ammonia first" (pg. 20)
This seems to talk against a large initial pitch and how it can negatively impact aromatics
This seems like the exact thing being discussed during the thread. Reading this extract it seems clearer why Fermaid O and Tosna are better:
"What’s wrong with adding too much nitrogen, or adding all the inorganic nitrogen (DAP) at once? A large influx of nitrogen as DAP throws the cell’s metabolism off balance, potentially leading to overgrowth of yeasts, runaway fermentation, flavor problems, nitrogen wasting, and leftover amino acids.
1) Yeast cell growth (biomass) depends on nitrogen content before fermentation, when yeasts are growing. Too much nitrogen available at that time leads to a lot of cells which then become ”hungry” later when nitrogen runs out.
2) Fermentation rate also depends on nitrogen. With too much DAP, yeasts may ferment too fast and too hot (they can even kill themselves with the heat, causing stuck fermentations). Also, fast or hot fermentations often have less complexity and less fruity aromas." (pg. 21)
Reading the yeast stages part further in the document might provide extra information to readers about nitrogen consumption vs time vs cell number growth.
While this document talks about dap, I think it might still be possible to create overgrowth with Fermaid O, especially since 1) above seems to refer to nitrogen in general and not just to dap.
Sorry Squatchy for seeming like an ass and giving you an arguable post only to provide evidence a few posts later. Seriously, all this evidence stuff makes me feel like an ahole
Info I found which supports my theory just from what I read in BSG catalog http://bsgwine.com/PDF/1.12.16_2016 BSG Wine Catalog PROOF.pdf
"Insufficient nitrogen has many negative effects on yeast growth and metabolism. Cell numbers, fermentation rate, protein synthesis (including the glucose transport proteins that bring sugar into the cell), and alcohol resistance all depend on the availability of nitrogen at the right time." (pg 10)
"DAP has been called ‘yeast candy’ because yeasts use ammonia so easily. They deplete the supply during growth phase and very early fermentation. The more ammonia that is present early, when yeasts are growing, the more cells are produced (“biomass”), all of which continue to need nitrogen throughout fermentation. A large biomassmay run out of nitrogen early." (pg. 19)
Does this say that a large initial addition will starve yeast later on?
"Despite the inconvenience, we recommend making multiple additions of products in which the nutrients are immediately available and do not have to leak out of partly autolyzed cells or dissolve slowly. Immediate availability gives much better control, allowing the winemaker to respond to fermentation kinetics by adjusting amounts and timing of the additions. A large influx of nitrogen as DAP throws the cell’s metabolism off balance, potentially leading to overgrowth of yeasts, runaway fermentation, flavor problems, nitrogen wasting, and leftover amino acids." (pg. 20)
A refernce to the overgrowth theory?
"Too much DAP, especially at the beginning, can prevent use of some amino acids: arginine, in particular. Leftover arginine is an ethyl carbamate
precursor, and can feed spoilage microbes like Brettanomyces and Lactobacillus. Amino acids are also aroma and flavor precursors necessary for the wine’s sensory profile. Adjust nutrient supplement timing so that the yeasts “eat their amino acids” instead of “spoiling their dinner” by gorging on ammonia first" (pg. 20)
This seems to talk against a large initial pitch and how it can negatively impact aromatics
This seems like the exact thing being discussed during the thread. Reading this extract it seems clearer why Fermaid O and Tosna are better:
"What’s wrong with adding too much nitrogen, or adding all the inorganic nitrogen (DAP) at once? A large influx of nitrogen as DAP throws the cell’s metabolism off balance, potentially leading to overgrowth of yeasts, runaway fermentation, flavor problems, nitrogen wasting, and leftover amino acids.
1) Yeast cell growth (biomass) depends on nitrogen content before fermentation, when yeasts are growing. Too much nitrogen available at that time leads to a lot of cells which then become ”hungry” later when nitrogen runs out.
2) Fermentation rate also depends on nitrogen. With too much DAP, yeasts may ferment too fast and too hot (they can even kill themselves with the heat, causing stuck fermentations). Also, fast or hot fermentations often have less complexity and less fruity aromas." (pg. 21)
Reading the yeast stages part further in the document might provide extra information to readers about nitrogen consumption vs time vs cell number growth.
While this document talks about dap, I think it might still be possible to create overgrowth with Fermaid O, especially since 1) above seems to refer to nitrogen in general and not just to dap.
Sorry Squatchy for seeming like an ass and giving you an arguable post only to provide evidence a few posts later. Seriously, all this evidence stuff makes me feel like an ahole
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Hey Stasis
No problem brother. I really appreciate you being here. I wasn't challenging you in the least. I was just saying I believe lots of people think they know something when in fact maybe they don't. I love all your imput here for sure and will always like to read what ever links you can add here.
I know very little other than what I can read on the web and in books. And yes we agree just because someone claims something doesn't necessarily mean it is so. That's why I tend to want proof from some whitecoats. I also know we all have a bias and many of the whitecoats are hired by someone to support the funding parties claims, or challenges.
We even know that as science uncovers new things old "truths"become obsolete as new info unveils itself. Thanks for the PDF. I will download it and more likely than not read through it tonight.
HAHA. I just went to the PDF. Obviously I was way wrong about reading it tonight. I know for sure I will be reading lots tonight.
No problem brother. I really appreciate you being here. I wasn't challenging you in the least. I was just saying I believe lots of people think they know something when in fact maybe they don't. I love all your imput here for sure and will always like to read what ever links you can add here.
I know very little other than what I can read on the web and in books. And yes we agree just because someone claims something doesn't necessarily mean it is so. That's why I tend to want proof from some whitecoats. I also know we all have a bias and many of the whitecoats are hired by someone to support the funding parties claims, or challenges.
We even know that as science uncovers new things old "truths"become obsolete as new info unveils itself. Thanks for the PDF. I will download it and more likely than not read through it tonight.
HAHA. I just went to the PDF. Obviously I was way wrong about reading it tonight. I know for sure I will be reading lots tonight.
most of that pdf is bsg marketing their products but hopefully there is a nice amount of new info too. Bsg also seem to have some very interesting products such as Superferm which is only 25% dap and lots of minerals and vitamins which they claim is ideal for problem ferments. I also liked the sound of Supervit which is only vitamins and minerals. Could be a good addition alongside fermaid O since Fermaid O's weakness is the lack of vitamins and minerals.
I like Lallemand better because they are more open with information and renowned than Bsg, but Bsg also seem to be quite open with their information here
I like Lallemand better because they are more open with information and renowned than Bsg, but Bsg also seem to be quite open with their information here
Wasn't able to follow the link. I would really like to read it though. It sounds exactly like what I have experienced. I recently posted a thread describing a problematic ferment, where I exceeded the total recommended Fermaid-O per TOSNA recommendation, but front loaded it, and tapered off rather than adding in equal measurements. My result was sulfur production by about the 1/3 break. So the idea that I'd created a much bigger bio mass than typical, and left that larger mass underfed for the rest of the ferment makes sense. I rescued the batch with another nutrient addition and a feeding of honey to lengthen the ferment and "scrub" the sulfur out with good fermentation. It worked, but now I'm wondering what aromatics I may have lost.
It also begs another question, and a possible experiment. Why would we not intentionally create a heavier biomass of yeast initially by providing greater than normal nutrient up front, but then adequately support the bigger mass with greater quantities of nutrient through the ferment? Effectively, a place to stay might be to calculate the recommended TOSNA additions, and double them throughout. Stronger ferment, cleaner, and finishing up quickly.
The most common reason for a larger biomass that I've read about is to minimize the chance of spoilage organisms taking hold or affecting the mead in any way. This is a practice commonly used by Oskaar himself and it makes sense. Although if we're going to be asking about evidence maybe we could ask for it here also.
The information above seems to indicate that a slower ferment will lead to a cleaner ferment with more aromatics.
So the only possible advantages of a stronger ferment seem to be:
1. "Finishing quickly" (but maybe not really). If the ferment is not as clean or aromatic you might still have to pay for this during aging. I.e maybe you're given a false sense of speed.
2. Giving less opportunity for spoilage organisms to affect the flavor or your mead. I am curious how much this will actually have an affect now that we're being more careful and using better products such as goFerm which already provide our yeast with an advantage.
Hmm.. at last we're clearly stumbling into ask Oskaar territory since he has personal experience here
The information above seems to indicate that a slower ferment will lead to a cleaner ferment with more aromatics.
So the only possible advantages of a stronger ferment seem to be:
1. "Finishing quickly" (but maybe not really). If the ferment is not as clean or aromatic you might still have to pay for this during aging. I.e maybe you're given a false sense of speed.
2. Giving less opportunity for spoilage organisms to affect the flavor or your mead. I am curious how much this will actually have an affect now that we're being more careful and using better products such as goFerm which already provide our yeast with an advantage.
Hmm.. at last we're clearly stumbling into ask Oskaar territory since he has personal experience here
Personally, when adding fruit to a mead, especially fresh fruit, I have always veered toward adding in secondary, or at least well after the primary ferment has begun and there is a significant alcohol presence. I think if there were a substantially stronger yeast presence at the outset, I would be more comfortable adding fresh fruit up front as well. That's just personal preference, as I'm aware that many modern mazers (can we just say "MMMs?" lol) add fruit up front in the primary without issue. I'm just operating from the Ken Schramm school of meadmaking. That's been my method, and it's done me well so far.
I was curious as to why the yeast need nitrogen throughout the fermentation, turns out the wikipedia article on YAN (the only one I found that I wouldn't have to pay for) was pretty informative but didn't quite answer my question .
I found a good explanation for why late-fermentation nitrogen additions aren't absorbed (taking in a protein through the cell wall also brings a hydrogen ion, which must be expelled to maintain the cell's internal pH and the environment is increasingly unfavourable for this proton pump activity). This article also explains that an amino acid called proline needs oxygen to be assimilated and is repressed by ammonium so is usually not assimilable during anaerobic fermentation so when you're doing your nitrogen assays in the lab you need to be aware of your proline levels a they can mess with your results.
What this article seems to imply is that the proteins are used for the glucose transport part of fermentation and that the cell can also break down amino acids to use their nitrogen and carbon components separately, but it doesn't say what else it uses the nitrogen for... Does anyone else know what yeast does with the nitrogen aside from make more yeast?
I found a good explanation for why late-fermentation nitrogen additions aren't absorbed (taking in a protein through the cell wall also brings a hydrogen ion, which must be expelled to maintain the cell's internal pH and the environment is increasingly unfavourable for this proton pump activity). This article also explains that an amino acid called proline needs oxygen to be assimilated and is repressed by ammonium so is usually not assimilable during anaerobic fermentation so when you're doing your nitrogen assays in the lab you need to be aware of your proline levels a they can mess with your results.
What this article seems to imply is that the proteins are used for the glucose transport part of fermentation and that the cell can also break down amino acids to use their nitrogen and carbon components separately, but it doesn't say what else it uses the nitrogen for... Does anyone else know what yeast does with the nitrogen aside from make more yeast?
To add something here, I read something awhile back, and I don't know where, so I can't footnote it: But what I read was that approximately 65% of yeasts cant utilize nutrient additions after 5% alcohol. I remember it saying that insufficient studies had been done to determine when and until what point individual yeasts could or could not utilize nutrient additions.
CG its like yeast act in mystrious ways... the article I was quoting much earlier speaks of how yeast can absorb amino acids, store it (in vacuoles?), use other nitrogen sources in the meantime rather than using the nitrogen already absorbed.... once the nitrogen they are eating is reduced they would vomit the amino acid they had once absorbed and go for something else. Sometimes in the very end when they have no other choice and are starving for nitrogen they will finally eat the amino acid they had absorbed and vomited way back. They just do different stuff depending on the availability and environment.. the funny thing is they are constantly changing the environment and availability for themselves and they could go back on their previous 'decisions'.
Since you mention proline, it also said that proline can sometimes be used slightly by yeast, but other times yeast actually increase the amount of proline.
I think nitrogen is almost directly related to the amount of growth in yeast. In fact huge amounts of nitrogen are used during the growth phase when compared to the rest of their life cycle.
This article here shows nitrogen use during 4 phases in fig 1 (pg. 2). Solid black is nitrogen in must, striped after growth phase, shaded towards the end, white is final amount. The actual density of sugars is stated in the caption. https://www.google.com.mt/url?sa=t&...IRno_cdMwhY4UWtlA&sig2=mnC3Wz4sOlCFmRn0z2JSWg
1. You can see that the huge leaps in nitrogen use always happen during growth phase i.e. the greatest difference in bar heights is between the black bars and the striped ones
2. Asp is an example of an amino acid which could either be consumed or actually created during fermentation depending on environment (temp)
3. Arg and others also show how amino acids can be absorbed, vomited, and later re-absorbed
4. If you were wondering about the temp differences in these two case studies, yes nitrogen is consumed less in lower temps
This study also says in pg.5 that nitrogen is mostly used initially for cell reproduction while during the stationary phase "most of the nitrogen compounds are dedicated to cell maintenance".
Way way back we were discussing what the limiting factor for yeast growth might be. The study here says that nitrogen is the limiting factor http://aem.asm.org/content/78/22/8102.full
Also quite interesting is the fact that certain yeasts are able to produce a larger biomass with the same amount of nitrogen... essentially we see what a yeast with low and higher nitrogen requirements do.
Since you mention proline, it also said that proline can sometimes be used slightly by yeast, but other times yeast actually increase the amount of proline.
I think nitrogen is almost directly related to the amount of growth in yeast. In fact huge amounts of nitrogen are used during the growth phase when compared to the rest of their life cycle.
This article here shows nitrogen use during 4 phases in fig 1 (pg. 2). Solid black is nitrogen in must, striped after growth phase, shaded towards the end, white is final amount. The actual density of sugars is stated in the caption. https://www.google.com.mt/url?sa=t&...IRno_cdMwhY4UWtlA&sig2=mnC3Wz4sOlCFmRn0z2JSWg
1. You can see that the huge leaps in nitrogen use always happen during growth phase i.e. the greatest difference in bar heights is between the black bars and the striped ones
2. Asp is an example of an amino acid which could either be consumed or actually created during fermentation depending on environment (temp)
3. Arg and others also show how amino acids can be absorbed, vomited, and later re-absorbed
4. If you were wondering about the temp differences in these two case studies, yes nitrogen is consumed less in lower temps
This study also says in pg.5 that nitrogen is mostly used initially for cell reproduction while during the stationary phase "most of the nitrogen compounds are dedicated to cell maintenance".
Way way back we were discussing what the limiting factor for yeast growth might be. The study here says that nitrogen is the limiting factor http://aem.asm.org/content/78/22/8102.full
Also quite interesting is the fact that certain yeasts are able to produce a larger biomass with the same amount of nitrogen... essentially we see what a yeast with low and higher nitrogen requirements do.
Something also VERY interesting is that when temps are 13C, the yeast use amino acids for cell growth rather than ammonia. Also, when temp is 13C the nitrogen use is more efficient (top-right pg.5)
Meanwhile, Fermaid O protocols such as TOSNA forces yeast to use amino acids exclusively for cell growth and also cell maintenance. I wonder if the efficient use of nitrogen under colder conditions is partially (if not wholly) due to the use of amino acids rather than something which just happens because of cold.
So many studies talk about differences in nitrogen use efficiency, I am becoming more convinced that talking about TOSNA and efficiencies is technically ok
Meanwhile, Fermaid O protocols such as TOSNA forces yeast to use amino acids exclusively for cell growth and also cell maintenance. I wonder if the efficient use of nitrogen under colder conditions is partially (if not wholly) due to the use of amino acids rather than something which just happens because of cold.
So many studies talk about differences in nitrogen use efficiency, I am becoming more convinced that talking about TOSNA and efficiencies is technically ok
This part of CGs post made me rethink something I had previously dismissed. I also had read the wikipedia article, found this interesting but it hadn't seemed significant until now. Thanks to CG I thought about it again these last couple of days. Proline is dismissed so much that it is not even considered as yeast assimilable. Let me put my following thought process into points
Proline is abundant in honey
- If someone were to take a sample of must to a lab and test for nutrients, the result would not include proline
- Proline is abundant in honey. In fact, proline makes up more than half of honey's amino acids. The following link illustrates this http://meadscience.blogspot.com.mt/2014/07/composition-of-grape-vs-honey-musts_30.html
Many honeys seem to have over 100ppm proline.
- The pie chart is skewed in the sense that proline seems to be just over 50% of YAN, but in reality the importance *COULD* be even more since proline is intermediate preference, rather than poor or no preference http://scholar.sun.ac.za/handle/10019.1/85797
- Furthermore: "degradation of proline is an integral step in the arginine catabolism pathway" (pg. 16, same source as above), which means that if proline assimilation is encouraged, it leads to the use of other amino acids, therefore the importance of proline can be even more that what appears in the pie chart
Proline is also very efficient in creating yeast biomass
- "Proline was found to give some of the highest biomass after 24 hours, however, at the end of fermentation it was found have one of the lowest biomasses. This is likely due to the presence of dissolved oxygen in the media which is consumed during the first 24 hours." (pg. 39, source same as above). Biomass formation also happens to be one of the most nutrient-need intensive times
Why proline is usually dismissed as a YAN source
- Proline is repressed by ammonia and lack of oxygen. This means that it is very difficult, if not impossible for it to be used in wine musts. Wine musts are not aerated as much as mead musts and grape must also contains a significant amount of ammonia
- In fact, "These three nitrogenous compounds - amino acids (excluding proline), ammonium ions, and small peptides - constitute what is commonly referred to as yeast assimilable nitrogen (YAN)"
However, proline might be significant in TOSNA
- In TOSNA, proline can't be repressed by ammonia since no ammonia is added to the must
- TOSNA could be 'underfeeding' musts during the growth phase, forcing yeast to assimilate proline - something they wouldn't do if there were other abundant amino acids which they prefer. This underfeeding leads to assimilation or proline, which leads to yeast not actually being underfed!
- Ammonia in any amount will make it very difficult, if not impossible for a yeast to assimilate proline. This is true even if the initial feeding of dap is 'underfeeding' the must similarly to how TOSNA is underfeeding. This is because:
"yeast making the switch from an inorganic to organic nitrogen source will enter a lag phase while they acclimate to their new environment. In this case the fermentation has probably not stalled – give it some time to switch over before deciding to re-pitch or add more nutrients."
By the end of this lag phase, yeast might be on the verge of quitting their growth phase
- In TOSNA, aeration is carried out for a very long time.
- The growth phase might also be extended compared to musts with dap since amino acid assimilation is more gradual. This could give yeasts more time to assimilate proline
Theory:
A large amount of factors *might* be coming together to make TOSNA efficient and possible. Yeast strain is probably a large factor, amino acid efficiency is possibly another, the switch of proline from a non-YAN source to a YAN source, and thus the seemingly 'magical creation' of an extra ~100ppm YAN *could*be another factor
Volunteers to test proline levels of TOSNA protocol musts vs Fermaid K SNA protocol musts before and after fermentation anyone?
Volunteers to test proline levels of TOSNA protocol musts vs Fermaid K SNA protocol musts before and after fermentation anyone?[/QUOTE]
I could be inclined to participate. My initial question is this! Wouldn't we need to all participate with the same honey? Could water values contribute to a skewed understanding? If we were able to determine that proline contributes to a better end result can one purchase proline in a quantifiable amount?
I could be inclined to participate. My initial question is this! Wouldn't we need to all participate with the same honey? Could water values contribute to a skewed understanding? If we were able to determine that proline contributes to a better end result can one purchase proline in a quantifiable amount?
