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Long Technical Posts, Parts 1, 2, 3, 4 Ed.
Note: This document collects and formats into a html file the 4 long posts referenced in the Sourdough FAQs discussing the detailed science of sourdough cultures and bread, May 1998.
The email addresses are left for identifying the poster but may no longer be valid.
He has recently reviewed a proof of a book I have written about masonry ovens and naturally fermented bread, and has commented in detail.
Those comments will interest those of you who are interested in the science and technology of sourdoughs.
This post and others that follow are for you.
If you ARE NOT interested in the subject, stop here, and save yourself from confusion and frustration.
Microbial growth can be divided in three stages.
When the organisms are transferred to a new environment e.
Eventually, the culture will become stationary, i.
For effective sourdough fermentation, one needs a lot of metabolically active cells.
After three or more refreshments, the organisms will reliably start to grow soon after inoculation and will produce enough carbon dioxide.
Things are different with yeast dough, though: there simply are so many cells that these have to cough only once to raise the dough.
Taken together, one can state the following: A The optimum temperature for sourdough lactobacilli is 32 - 33°C.
At 37°C and 20°C, the generation time is twice as long.
B At 39 and 15°C, the generation time is four times as long.
C At 41°C and 4°C, no growth is observed.
So: if several refreshments are done above 32°C, the yeasts will drop out eventually.
The optimum pH for lactobacilli is 5.
Eventually, the lactobacilli flora may change, with more acid tolerant lactobacilli e.
Such a sourdough is found in the Vollmar and Meuser continuous sourdough fermentation machines there are 6 operating in Germany, and a diploma candidate in our department characterised the microflora of several of these: as the machine is operated with a 50% inoculum, the pH is never above 4.
Increasing salt concentrations inhibit growth of lactobacilli, but yeasts tolerate more salt.
No salt is added to the sourdough until the final bread dough, but the dough yield affects the salt concentration: with a low dough yield little waterthe salt ash is dissolved in a smaller water volume, and the salt concentration goes up: resulting in a slower fermentation.
Surprisingly, Markus has found most of the predictions to come true when he was looking at the cell counts at different temperature, size of inoculum, salt concentration, and pH in rye dough.
The variation of the inoculum size was interesting: If he reduced the inoculum size by 2, he had to wait almost exactly one generation time one doubling time of the lactobacilli longer until the dough has reached the same cell counts, pH, titrable acidity, and so on as the dough with the higher inoculum.
Thus, a scanty inoculum means one generation time longer fermentation.
The generation time of L.
The question is, whether these findings are true for all flours and for all 5 />Differences may be between rye flour and white wheat flour: in white wheat flour, the enzyme activities are Межкомнатная дверь с Альфа Миланский орех low that the organisms may run out of food before the critical pH lactobacilli or the critical acetic acid concentration yeasts is reached.
I'm still digesting much of it if you can forgive the punbut I had a few thoughts.
I found Michael Ganzle's "comment 1" especially informative.
So I thought I'd talk about some of them.
What the assumption doesn't explain is the steep drop in population growth at sub-cell-death temperatures above "optimum," and that "zero growth" is Наклейки светящиеся в темноте Звездное небо НЛО above freezing.
That said, it should work very well between ~10C and ~32C.
So we see that most of the interesting growth phenomena particularly with respect to yeast versus bacterial growth happen at extreme temperatures.
This has direct bearing on certain suggested methods of starter maintenance: High Temperature Maintenance The FAQ contains an interesting entry on how one might manipulate the microbiological population of a starter by refreshing it at high temperature.
This is summarized in One should carefully note and I would suggest that the FAQ привожу ссылку annotated to reflect that "if several refreshments are done above 32C, the yeast will drop out eventually.
Many of us keep them exclusively in the refrigerator.
The latter practice may not be such a good idea.
Unfortunately, an observation of "froth" or other visible starter activity cannot necessarily confirm the presence of yeast.
On the bright side, I imagine it is possible that the yeast in a constantly-refrigerated culture may mutate to become more low-temperature-tolerant, or more likely a low- temperature-tolerant yeast may "invade" the culture and take the place of the original yeast.
Either way, although you may find yourself with a perfectly good culture, it will not be the same culture with which you began.
This shouldn't affect people who store their starter in the refrigerator but generally увидеть больше it at room temperature.
Eventually, the lactobacilli flora may change, with more acid нажмите чтобы увидеть больше lactobacilli e.
Many 5 us feed our starters by "doubling.
I wonder if this is true for our typical US white wheat flour, which includes ~.
I never supposed that this might be so.
I'll have to reconsider my thoughts on the use of diastatic malt syrup as a worthwhile sourdough dough additive.
Many of us keep them exclusively in the refrigerator.
Either way, although you may find yourself with a perfectly good culture, it will not be the same culture with which you began.
If you really are attached to a particular starter, it's simple enough to freeze a sample.
Constant characteristics may be important to a commercial baker, but I don't see any reason for the sourdough hobbyist to be so limited.
I play with my starter.
I particularly like to change what I feed it for a month or so and see what it does.
I started it with half a dozen lactobacillus sources, and I bet all of them are still in there, in varying concentrations that feeding can change.
I commonly feed potato starch.
I also have tried rye flour, oat flour, barley flour and corn flour.
I was using milk for a while, but it started to get to "limburgery" to the point that the cheese flavor was coming through in the finished bread, so I dropped the milk and the flavor shifted back.
The corn flour made a real pucker power sour mash.
I didn't feed 100% corn, but mixed it half and half with wheat flour.
I never refrigerate the starter.
I keep it on top of the refrigerator, where the temp is 23 degrees C.
When I feed it, I use hot water, though not so hot as to kill the culture.
If I'm only feeding a little, I use almost boiling water, if I'm doubling or tripling I use hot tap water.
Except sometimes I don't feel like it and use regular tap water.
I haven't had a bit of trouble attaining a fine tasting sourdough.
Some types of starter do better in some recipes than others.
The milk based starter made the best double sponge Swedish Rye, but was too strong flavored for sourdough french.
It's all 5 how you cook.
An amateur can afford to take more risks than a professional.
Also, if what you're doing makes bread that you like, more power to you.
That said, there are some comments I'd like to 5 on your post for the sake of clarity.
Actually, it's not so simple.
There is fairly strong evidence that many sourdough organisms will not survive freezing.
On the other hand, Carl has been drying and freezing his sourdough culture for years see.
However, it is likely that Carl's starter has responded to this treatment by evolving freeze-tolerance.
Such узнать больше здесь cannot be assumed for all sourdough cultures.
Anyone who plans to freeze a sourdough culture other than Carl's would be well-advised to "test-freeze" a sample and make sure that it recovers from freezing with its unique characteristics intact.
Well, there are limits and there are limits.
I would never suggest that home bakers abandon experimentation.
However, unpredictable starter behavior is often cited as one of the most limiting aspects of sourdough baking.
Mistrust or misunderstanding of one's starter is a primary reason why some bakers chose to rely on added bakers' yeast to leaven the dough.
I particularly like to change what I feed it for a month or so and see what it does.
I started it with half a dozen lactobacillus sources, and I bet all of them are still in there, in varying concentrations that feeding can change.
I'll take that bet, because I bet that you're wrong there.
Dan's recent "technical" posts also showed how the percent inoculation and consequent pH effect can cause certain lactobacilli to drop out while others become dominant.
A starter is basically a little "Darwin Machine.
The pre- existing microorganisms do have a survival advantage, because they have established a mutually beneficial symbiosis.
But a 5 change in environment could easily take away that advantage.
It is true that certain sourdough cultures have been scientifically shown to retain the same microorganisms over many, many years -- but these are consistently-maintained cultures.
I keep it on top of the refrigerator, where the temp is 23 degrees C.
When I feed it, I use hot water, though not so hot as to kill the culture.
If I'm only feeding нажмите чтобы увидеть больше little, I use almost boiling water, if I'm doubling or tripling I use hot tap water.
Like I said, if it works for you -- great.
I would never recommend this kind of starter maintenance to anyone.
At the temperature you are keeping your starter, one would have to triple it at least once a day to keep the pH low enough for L.
From what you describe, I would imagine that the microbial population of your starter is in almost constant change.
I guess I forgot to mention that I used nonfat milk.
I источник it was actually penicillin, and I was getting a true "limburger" culture going in there with the sourdough.
It was certainly interesting, and actually quite tangy, but it did have an unfortunate aroma that didn't cook completely out.
Dropping the dairy products solved the problem.
It may have been a yeast strain.
Anyone who has ever worked with salt rising bread knows that yeast can make some pretty pungent odors.
Some day I'm going to develop a saline starter and see what it tastes like.
Summer is coming, and I could set up a rising box in the garage when it gets warm enough.
Making salt rising bread in the kitchen is rude.
In a dry year, the amylase activities may be rather low, so that the problem with the acidification is not very prominent.
It may also be noted that rye not only has a higher amylase activity, a but also a higher protease activity, which is important for the flavor development.
Type 550 or 55 is used only for white wheat bread, not a very big share in the market.
As far as the enzyme activities go, see above.
The difference in enzyme activities is also important for the microorganisms: in rye flour they always have enough sugar available due to the high enzyme activities, whereas in white wheat flours, glucose but not maltose may be depleted during the fermentation.
Rye amylase resists inactivation by heat to a greater extent than wheat amylase.
Also: see above ---------------------------------------------------------- No laboratory test assesses taste, even though there are real differences in the taste and texture of bread baked from otherwise similar flours.
Hammes in our lab, and Prof.
It may be useful to distinguish between taste and aroma.
Taste happens on the tongue, where only salty, bitter, sweet and sour can be evaluated.
Aroma is perceived in the nose: during chewing, the volatile compounds diffuse to the receptors mind that acetic acid, but not lactic acid is volatile.
Thus, the latter is just sour, while acetic acid has aroma.
There are about 15 compounds each about 10 of them are the same for wheat and rye bread, furthermore, crust and crumb have different aroma volatiles with which the impression of rye or wheat bread is given This is work of Prof.
To group the compounds according to their generation in dough, one may say that: ithey are produced by fatty acid oxidation by cereal enzymes upon dough mixing several baking aids contain soy flour with additional lipoxygenase activity, and prolonged storage of whole flour leads to rancidity as well.
More of them by yeasts, probably, though acetic acid also plays an important role.
However, the precursor chemicals for this type of reactions are amino acids, and the levels of amino acids in flour is very low.
In wheat, there is little, if any proteolytic activity proteases degrade protein to amino acidsso, whatever amino acids there are produced by enzymes of lactic acid bacteria there has been nice work done on proteolysis in wheat dough by Dr.
Marco Gobbetti at the University of Perugia.
In rye, the proteolytic activity of the flour is much higher, but the proteases need acidification to a pH below 5 to have their optimum activity and, of course, a long fermentation time gives the enzymes more time to work.
Sourdough yeasts are consuming amino 5, meaning a sourdough with a high yeast count has fewer amino acids than a dough containing only lactobacilli.
The most important flavor compound in rye crust, methional, as well as in wheat crust, 2-acetyl-pyrroline, are Maillard products of the amino acids methionine and ornithine, respectively.
There are a few good working hypotheses: Some, but not all strains of L.
Martinez-Anaya in Valencia, Spain think that maltodextrins may delay bread staling, though.
The first work during my diploma thesis was to look for phytase enzymes in lactobacilli from sourdough.
After 8 weeks, I figured out that there is none, and shortly thereafter it became clear that both wheat and rye have sufficient phytase activity, all it takes is some acidification.
Cultured from the environment is certainly true - L.
No other scientist has been able to isolate L.
A possible source may be the humans: there are all kinds of lactobacilli thriving in the mouth, the intestines, etc.
Hammes met a South African Microbiologist who claimed to have isolated L.
Not only are there many strains of yeast and bacteria that can form them, we need terms in English for the various stages of natural leavens.
Some sourdoughs are quite close to infinity, as far as the generations go.
Then, the definition of e.
What makes is fascinating is that the microbiology of Böcker Reinzuch Sauer HAS NOT CHANGED in the past 30 yeast, i.
There are two strains of L.
Remarkably, the two strains of L.
Then, the definition of e.
Fortunately, what is good for the sourdough lactobacilli seems also to be good for bread quality There are other microorganism in fermented food that require the man-made habitat: e.
Tetratenococcus halophilus growing only in soy mashes, and Oenococcus oeni, occuring in wine only.
What is important, is that as soon as you change your parameters, you may change the microflora.
And later: the organisms have been refined by thousands and thousands of sourdough - refreshments, much more effective than any microbiologist of food scientist could ever be.
Besides, we know what kind of organisms do grow in sourdough - but how flavor production takes place, and which fermentation products delay bread staling is largely unknown - so other than gas production, I could not think of a property of lactobacilli in which to select a strain.
This kind of co-evolution makes some natural leavens remarkably stable приведу ссылку regularly maintained.
But the consistency in maintenance is crucial one is allowed to err to one side or the other from time to time, though.
The difference is raw material and production process.
Hammes thinks that L.
He still has to prove his point, though.
Gobbetti says that L.
As far as I know, no 5 antimicrobial compound in dough has been characterised.
As far as the 5 goes, rye only about as important as wheat only.
The situation is different for bagels, pretzels, and so on.
Which is why industry is funding flavor research at the Universities of Hohenheim and Munich.
Between 1 and 20% inoculum, lactobacilli grow at the same speed giving rise to the dependency of fermentation time and inoculum size explained earlier.
Sugihara, who participated in the characterization of the flora of San Francisco sourdough and several other cultures, was asked whether natural sourdough cultures could be contaminated with commercial yeast.
His reply was no, not if you have a stable culture that is continuously maintained with the same conditions and ingredients.
Sugihara is certainly right here.
The volume is somewhat smaller, though.
The yeasts are fewer in numbers, but larger in size.
Dough yield and temperature are much less important; as far as Spichers investigations go, I think that the higher lactic acid content of doughs with higher temperatures or higher dough yields he measured is due mainly to the faster fermentation at these conditions.
The amount of acetic acid produced is controlled mainly on the availability of fructose.
If the organism wants to produce the more oxidized end product, acetic acid, another substrate must be reduced.
The ratio of mannitol to acetic acid in dough is about 1.
There is a lot of fructose in dough, but not all of it is available for the lactobacilli.
Yeasts liberate some of the fructose bound in glucofructans that thus becomes available for the lactobacilli there is some nice work that has been done by the Sugihara group, Saunders et al.
If you to too high with the temperature, you slow https://ugra.site/100/tecniq-grafit-mat-texnik-grafit-mat.html yeast growth, and the acetic acid levels in the dough decrease.
For bakers, an easy way to increase the acetic acid content is to add sugar that is sucrose, a consisting of glucose and fructose.
Sugar addition not too much, 1 or 2% may speed up fermentation in white wheat flours: as mentioned above, in contrast to whole wheat flour and rye flours, the enzyme activities and thus the sugar concentrations are rather low and may limit microbial metabolism.
As far as the influence of acetic acid and lactic acid on flavor go: lactic acid has no influence on aroma, only on taste, while acetic acid is an aroma volatile.
So, I think it is not so much the ratio Likely.

Калька ProMega Engineer (А4, 70 г/кв. м, 100 листов) think lactic to acetic acid, but more simply the acetic acid content that matters.
It was stored the way you described here, and did come out well upon refreshment.
The Böcker Reinzuchtsauer is also distributed as stiff, refrigerated product.
I think the company источник not guarantee storage stability of more than 4 weeks, though.
There has been nice work done in Rudi Vogels lab on the microflora of a freshly started sourdough: first, there are Enterobacteria Escherichia coli, Salmonella, Enterobacterhighly undesirable organism that stink terribly, then there are homofermentative lactobacilli good, but no gas productionthen acid-tolerant, heterofermentative lactobacilli.
I think, this took about 48 hours at 30°C.
The stink at the beginning does not matter as the organisms will be diluted out or die eventually.
Peter Stolz said that one every 24 hours will suffice, if intervals are much longer than that lets say more than 3 daysdifferent, more acid tolerant organisms may evolve e.
Most of the typical sourdough yeasts resemble C.
I find students almost done with their degree still have difficulties with this concept.
Markus Brandt observed this in doughs rye flour, TA 180 if more than 2% salt were added.
Schieberle in Munich has done several nice studies: he supplied doughs with amino acids and demonstrated that the levels of aroma compounds in the bread were increased.
So, formation of aroma precursors during dough fermentation is crucial for the 5 reaction.
It would be valuable to have that information summarized as to pertaining to SF type white sourdough bread, on the one hand, to German rye bread on the other.
Desem нажмите чтобы увидеть больше not seem to be a big subject at r.
I have been particularly amazed by the news that one of Professor Gänzle's colleagues is apparently counting microorganisms in dough.
To me, that seems like making a census of monkeys and snakes in the bush from an aircraft.
The mystic may arise from the fact that the "long technical post" was written as part of a personal communication and not for a large "audience": things may have gotten a little bit out of context.
As far as the application to recreational sourdough bread baking goes, it should contain information as to how acid production in sourdough is controlled, and how the sourdough starter can be treated to keep the lactobacilli happy.
As the organisms are pretty much the same in white wheat sourdough and rye sourdough, this information relates to either one.
To my thinking, the differences in taste between "San Francisco Sourdough Bread" and other breads are more likely to result from the different raw material, fermentation and kneading process and baking than from the differences in the sourdough starter.
As far as other subjects go - influence of sourdough fermentation and raw material on aroma and texture - I don't have much more to offer than the fact that sourdough bread usually tastes better than "straight yeast" bread which most of you probably knowand a few working hypotheses.
By the way, you're a little bit ahead of time as far as my academic merits go.
To me, that seems like making a census of monkeys and snakes in the bush from an aircraft.
To count, the sourdough is diluted 1 in 10 million 7 one in ten dilutions and poured in an agar plate.
Each of the about 100 cells of the dilution starts to grow and is visible as a colony a few days later.
Or, to translate to the census of monkeys in the bush: Читать далее the monkeys evenly i n the bush making sure that they can't mix afterward and wait until the "families" produced by each pair of monkeys is big enough to be visible from the aircraft.
We need a Professor right now!
So it seems like we can count on Markus' counts.
What I hope for most is a temperature time plot or other such instruction to determine how times should be adjusted for varying temperatures to get optimum culture feeding interval sponge development time rise time.
The data presented seem to give a few points on such curves, quite similar in shape and slope on semi log plots for yeast and bacteria.
It was interesting to observe that yeast смотрите подробнее relative to bacterial growth is retarded towards the high and low temperature limits.
So when Andreas tells us the bacteria "like" high https://ugra.site/100/evolution-suede-30x30.html, he is meaning that they tolerate high temperatures better than yeast does.
No doubt some others will also perceive that this high, and similar low, temperature behavior may provide a means to get really sour culture and sponge.
It also makes it seem silly that some people advise to "retard" at ~50 F.
Several things continue to baffle me well, more than that, but let's take right!

Кофемашина Markus A-2GR/R really few : If the bacterial generation time is shorter than yeast's generation time, why doesn't periodically fed starter culture become all bacteria?
Another baffling thing is the accumulation of acids and other metabolic products as they may affect growth kinetics.
Not продолжить чтение that, but also the suspicion that bacteria may thrive on yeast deciduem, which would lead one to suspect that bacterial growth may accelerate when yeast becomes disadvantaged by its depletion of its nutrients.
перейти на источник things make it hard to believe that the compound system may be described by very simple rules.
My practice of maintaining my starter culture with bi- or tri weekly feedings in the refrigerator appears to defy logic since yeast, by Markus' numbers, does not seem to grow at refrigerator temperatures, though bacterial growth may only be impeded.
But I guess one could assume that my organisms have adapted mutated changed whatever.
SDI's reported practice of maintaining their cultures in the refrigerator with semiannual feedings seems perhaps a bit off base.
A third baffling thing is the relationship between number of cells and activity.
It would be nice to be able to assume that the concentration of microorganisms predicts their activity leavening, flavoring, etc.
If one were to attempt to predict practical parameters from cell count data, some assumptions about that relationship would seem to be necessary.
Be assured, my esteemed Professor, that there is a world of difference, in my case, between serious confusion and desire посетить страницу pick nits.
Here in USA, all vat is needed to be a Professor is to talk a little bit funny.
Umlauts are good, too.
I have still not found the keystrokes for the little superscript 0 that designates degrees.
I have still not found the keystrokes for the little »superscript 0 that designates degrees.
Try ALT-0186 for Dº -- -Kenneth If you email please remove the "SPAMLESS.
I would love to know how the technical underpinnings of retarding.
The data are that retarding improves flavor.
The question is how?
I will use the old rule по ссылке something better comes along.
Anyway, it is not a rule, but a means of estimating.
The Brandt numbers crudely fit a 5 or 6 degree ºC.
I am betting on a 8º "rule".
These kinds of rules are for lumping everything, even that which surpasses human understanding.
I will use the old rule until something better comes along.
Anyway, it is not a rule, but a means of estimating.
The Brandt numbers crudely fit a 5 or 6 degree ºC.
I am betting on a 8º "rule".
These kinds of rules are for As I said.
The question is "estimating" what?
The What that is estimated is a miniscule part of the story, as we both know.
I did a small amount of copy editing.
Hopefully I didn't affect any nuances of meaning but just got rid of a few typos.
My thanks to Michael and Dan for very graciously sharing their correspondence.
Cheers, Darrell ---------------------------------------------- Date: Thu, 13 Feb 1997 10:49:32 +0100 MEZ From: Michael Gaenzle To: Subject: sour dough microbiology MIME-Version: 1.
Your letter to Prof.
Hammes has reached Hohenheim, and Prof.
Hammes has asked me to take care of the communication.
Please feel welcome to address questions to us concerning sour dough microbiology and technology!
I will mail two recent publications or our lab concerning the physiology of sour dough lactic acid bacteria by mail, ссылка на страницу as they may take a week or longer to reach you, I will give a few comments on the questions in your letter: - yeasts do not produce appreciable amounts of either lactic or acetic acids, their main metabolites are ethanol and CO2.
If acidification of the dough is desired of required e.
Thus, doughs acidified with homofermentative lactic acid bacteria LAB contain but little acetic acid.
As homofermentative lactic acid bacteria do not produce CO2, yeast must be added to ensure leavening of the dough.
Heterofermentative lactobacilli produce lactate, ethanol, and CO2 from hexoses most strains do not ferment pentosesHOWEVER, if additional substrates are present that serve as electron acceptor to balance, acetate is produced instead of ethanol.
I do not 5 whether or not you are familiar with the concept of the "redox balance": Degradation of hexoses via the pentose-phosphate pathway as employed by heterofermentative LAB results in phosphorylation of ADP to ATP, and in the reduction of NAD to NADH.
As there is no use for NADH, it must be oxidized to NAD again.
In the absence of other substrates, acetyl-Phosphate is reduced to ethanol, with two NADH becoming oxidized to HAD in the process.
If either fructose, oxygen, citrate or malate are present, these become reduced to mannitol, H2O, lactic and acetic acid, and succinate, respectively, and acetyl-P is dephosphorylated to acetate.
The consequence for the molar ration of lactate:acetate fermentation quotient, FQ in sour dough fermentations is, that acetate in produced only if one or more of the above mentioned co-substrated is present.
Oxygen is present only in the beginning of the fermentation, and the amounts of oxygen are too low to result in significant amounts of acetic acid, though, in principle, it is possible to increase 5 acetate content by aeration of dough.
Fructose is present in sucrose and other glucofructans with higher molecular weights.
Fructose is released from these compounds by cereal or dough enzymes many strains of L.
The ration of mannitol : acetate in sour dough fermentation is approximately 2:1, suggesting that fructose is the как сообщается здесь important electron acceptor.
Thus, the effect of substrates and oxygen on the FQ is nicely explained by the metabolic characteristics of the dominating fermentation organisms.
Spicher reports that softer doughs lead to an increased FQ; an increase in temperature results in higher amounts of lactic acid, while the amount of acetic acid remains more or less the same, thus, the FQ is increased again.
I do not have a straightforward explanation for these phenomena, but changes in dough yield and temperature will result in changes in buffering capacities of the dough, modified activities of cereal and microbial enzymes, as well as a changed ration of yeasts : lactobacilli counts, all of which are likely to influence the FQ.
Yours Michael Ganzle ------------------------ Dear Michael Gaenzele Thank you for sending one of the most gracious letters I have ever received in response to any kind of an inquiry.
Since I wrote to Prof.
Hammes I have been able to copy a number of articles from English language publications by Drs.
Brummer, Spicher, Vogel, and so forth.
Unfortunately, some of them have been in non-technical journals and were thus short on details, and even the less technical ones were not as clearly and idiomatically written as your letter.
I DID have a hard time understanding what was meant by Dough Yield, for instance, although I had figured it out before I got your letter.
I am still not sure I understand some of the statements those authors made about the подробнее на этой странице content of doughs such as the units of measurementbut I have been piecing things together by looking at all the articles cumulatively.
Your letter has clarified a great deal.
I will put stars next to my current questions to make THIS letter easier to answer.
One problem for me was that I did not realize how predominant rye flours were in German sourdough baking.
I know that typical rye pentose is about 8% and that pentose viscosity is important in gas-trapping in rye doughs He and Hoseney, 1991 but I still don't know how an acidified rye dough behaves differently from a more neutral one.
I also do not understand why Brummer says "Anstellgut" is a non-translatable term.
As for your answers to my previous questions, thank you-- I will look this material over again, and let you know if I have questions.
I will NOT put your address or email address in the posting, unless you want me to.
Please let me know, as I think it might become part of the FAQ file there Frequently Asked Questions.
I will forward your entire letter to a very few people in academia here who have been helping me, so you might hear from one of them.
Dan Wing ----------------------------- Date: Fri, 14 Feb 1997 15:50:30 +0100 MEZ From: Michael Gaenzle To: Dan 5 Subject: Re: sour dough microbiology MIME-Version: 1.
I do not mind if the answer is posted to the rec.
To answer a few of your questions: I Https://ugra.site/100/matrichniy-kommutator-6h6-video-i-stereo-audio-100-mgts.html is no rye bread without acidification of the dough.
Rye flour does not contain gluten or a different type of gluten that does not have the gas-retaining CD-ресивер Magnat MC 100 that the structure of rye bread relies mainly on gelatinized starch.
Rye flour does have a higher amylase activity than wheat flour, furthermore, the gelatinization temperature is a few degrees lower than that of wheat starch.
Thus, with the temperature optimum of rye amylase being about 50 - 52C with substantial activity up to temperatures of 70C and starch gelatinization starting at 55C, starch is degraded during the baking process UNLESS the amylases are inactivated by lowering the pH below 4.
The situation is exacerbated if there was wet weather during the harvest, as germinating rye has higher amylase activities and the starch granules are damaged, thus facilitating hydrolysis.
II "Anstellgut" is more or less the same as the continuously propagated wheat starters of the SF sour dough bread, so no harm is done if it is translated as "starter sponge" or something like.
German sourdoughs usually are rye based for two reasons: 1 Due to the climatic conditions in Germany, especially in the northern and eastern parts that make it difficult to grow wheat, rye flour is just as important for bread production as wheat flour.
Starter sponges are not necessarily propagated separately.
If the dough is taken care of according to traditional methods, it is re-inoculated three times to produce bread dough reading Bruemmer and Spicher, you probably have already encountered the "three stage sour dough method.
This makes 3 - 4 inoculations a day, the ratio of sour dough to fresh dough being approximately 1:3.
One has to 5 a point of it: there is no typical sourdough without continuous propagation!
The microflora of these rye starters is actually the same as for wheat starter in SF or Italy: Lactobacillus sanfrancisco and Candida milleri or Saccharomyces exiguus.
The pH of a ripe sour dough will be between 3.
The total titrable acidity TTA depends on the flour employed: as the lactobacilli acidify to pH 3.
Furthermore, if "hard" water with high concentrations of Me2+ CO3- is used, the TTA will be higher.
As the propagation of sour dough is very time consuming if the full leavening capacity of the organism is to be obtained, quite a few processes have been developed in Germany that ensure that the dough is acidified or that the sour dough added to the bread dough contains enough acid to bring the pH of the bread dough below ca.
Leavening is achieved by bakers yeast.
The dried dough is sold much more readily if it can be called sourdough.
The TTY of that dough is high enough to use it for baking, but as the organisms are rather stressed in such an environment, they will not contribute to the leavening of the dough.
Such doughs do not contain lactobacillus sanfrancisco, but other lactobacilli that are more acid tolerant the ph of such a dough reaches 3.
One or two stage processes usually do not ensure that the lactobacilli in the dough are fully metabolically active if the bread dough is prepared, thus, the leavening 5 is rather poor, but enough acid has been produced.
As far as I know I never made a survey, thoughonly few bakers make bread with traditional processes without bakers yeast added to leaven the dough.
Acidification of the bread dough with sour dough is rather common, and the sensory quality of such bread is quite close to that of bread made without bakers yeast.
Straight processes with bakers yeast and chemical acidification citric, lactic, and acetic acid, or mixtures thereof are also quite common to produce rye bread.
Acetic acid is more volatile than lactic acid, thus, it's impact on the flavor is more pronounced than that of lactic acid.
Spicher says that a ratio of 20 acetate to 80 lactate is optimal.
It must also be taken into account, that the lowering of the pH influences the formation of other aroma compounds during the baking process.
The acetic acid is furthermore important as growth of spoilage organisms such as molds or rope causing bacilli Bacillus subtilis is inhibited by high acetic acid concentrations.
I hope that I could answer your questions With kind regards Michael Ganzle -- Darrell Greenwood, Vancouver, BC My web homepage.
Sorry for the duplication.
I have taken the following quotes from нажмите чтобы увидеть больше sub-page of -- an interesting site on yeast genetics.
Their data concerns standard bakers' yeast, but I think much of it is applicable.
When a growth medium is inoculated, the cells require a period of preparation before they start dividing.
Following this lag period which may be up to several hours they rapidly enter the exponential phase during which their number and mass double at equal time intervals.
After a period of growth at a relatively constant exponential rate, some environmental condition becomes growth limiting https://ugra.site/100/rascheska-beurer-ht10-goluboy.html that the rate of increase diminishes and growth eventually stops.
The population and mass become constant.
The culture remains stationary and the cells remain viable for several hours; if the culture is refrigerated the cells remain viable for months.
Eventually the cells die, and at room temperature or warmer they will undergo autolysis: their own digestive enzymes become active and they literally digest themselves, reducing their proteins and nucleic acids to their simpler components; they produce a particularly unpleasant stench in the process.
This tells us a lot of things.
For me, one of the most interesting was that the yeast in our case we could reasonably include bacteria as well does, in fact, reach a stable population.
In fact, their text seems to indicate that the microorganisms in a refrigerated starter remain at high concentration for quite a while months after maximum population density is reached.
The second thing, that I am kicking myself for not remembering earlier, is autolysis.
This phenomenon somewhat supports Dick's idea that proteolytic enzymes are released primarily after fermentation slows down.
However, this assumes that that the yeast have reached the point of starvation, and I doubt that this happens during the fermentation of a dough.
Further, as mentioned above, autolysis produces a distinctive and very unpleasant odor and flavor.
I am familiar with this from my brewing and it's hard to miss.
So, I imagine that autolysis isn't a major cause of protein degradation during a sourdough rise.
On the other hand, this might be of concern in a thin unrefrigerated starter.
Under aerobic growth conditions they can support growth by oxidizing simple carbon sources, such as ethanol, acetate or glycerol.
If they have adequate oxygen, they will completely oxidize their carbon sources, usually sugars, to carbon dioxide and water.
However, under anaerobic conditions, deprived of oxygen, yeast can convert sugars only to carbon dioxide and ethanol, recovering less of the energy.
In either case, growth will be limited by some essential nutrient or the accumulation of the toxin.
In liquid they must be stirred or shaken if they are to remain aerobic; otherwise, they settle to the bottom of the container, consume the dissolved oxygen, and grow anaerobically.
I am familiar with this from my brewing and it's hard to miss.
So, I imagine that autolysis isn't a major cause of protein degradation during a sourdough rise.
On the other hand, this might be of concern in a thin unrefrigerated starter.
I know this unpleasant odor.
Sometimes during the summer when 5 bakery reaches temperature of +95, the levain will at times ferment too fast and will collapse in on itself.
About детальнее на этой странице hours or so after this the levain begins to get an unpleasant smell to it.
It is still usable at this point, but not for much longer.
Before that point we have made another узнать больше, so that the bread dough will not be effected.
Once in a while the clean up crew forgets to dispose of the old levain and, let me tell you, when you find it, take the cover off you know what it is and you want to get it out of the подробнее на этой странице room fast.
Their site is at and their publication is called "Cereal Chemistry.
CChem 37:415 1960 : Yeast cells were quantitatively recovered from dough by a process in which.
Dick had speculated earlier that the scientific data on microorganism growth привожу ссылку a dough as opposed to in liquid or some other medium might be sparse due to the difficulties inherent to the medium.
Since they have been doing it with yeast for around 40 years, probably not true.
CChem 48:121 1971 : The stretching characteristics of gluten are found to be changed markedly upon incubation with proteolytic enzymes.
Increasing concentration of enzyme caused a progressive decrease in gluten consistency.
CChem 57:314 1980 : Gluten was fractionated into acid-soluble and acid-insoluble protein fractions.
The dough-strengthening effects obtained when gluten proteins were added were mainly due to proteins present in the acid-soluble gluten fraction, whereas the acid-insoluble gluten proteins at higher levels had a slight dough- weakening effect.
Addition of increasing levels of gluten to the base flours significantly increased loaf volume.
Similar increases in loaf volume were also obtained by addition of the acid-soluble gluten proteins.
Addition of acid-insoluble gluten proteins significantly reduced loaf volumes This was very interesting, in that it seems to indicate that the presence of acid can have a marked affect on the quality of the gluten.
This is further supported by the following article.
CChem 54:1249 1977 : Acid solubilization was detrimental to loaf volume at pH values below 4 for glutens from good- quality flours and at pH below about 4.
Impaired loaf volume was attributed to diminished hydrogen bonding caused by cleavage of amide groups from the gluten proteins during solubilization in acid.
With respect to sourdough breads, the following study is relevant to this topic.
C Chem 55:683 1978 : A combination of organic acids isolated from San Francisco sourdough and NaCl profoundly affected dough properties.
Mixing time and stability of dough were greatly decreased when organic acids alone were added.
Salt had the opposite effect, however, it increased mixing time and dough stability.
The effect was attributed to proteolytic enzymes, because the optimum pH of 4.
CChem 41:443 1964 : Self-digestion of flour showed a pH 4.
Both dough-mixing and the presence of sodium chloride substantially reduced the proteolytic activity of flour.
The performance of the fermenter can be improved and stabilized by adding starting cultures of yeasts isolated from sourdoughs.
Fermenting sourdoughs with added yeast showed a significantly higher acid formation than did those without P greater than 95% added yeast.
The accelerated acid formation was due almost entirely to additional production of acetic acid.
This effect was independent of the strain of yeast.
This is an interesting insight into output side of the relationship between bacteria and yeast in a sourdough.
I find it interesting that the presence of yeast increased acetic acid which isn't really the kind we want, is it?
CChem 55:461 1978 : Changes were observed in the pH, total titratable acidity TTAand lactic and volatile C2-C5 organic acid contents of commercially prepared sour starter sponges, bread doughs, and fully baked bread.
The results showed that lactic and acetic acids composed most of the total TTA.
Gas-liquid chromatography, however, showed that six other minor acids propionic, isobutyric, butyric, alpha-methyl n-butyric, isovaleric, and valeric acids contributed to the TTA of the fully fermented starter sponge, the fully proofed bread dough, and the baked bread 1.
Baking increased the pH negligibly but decreased the TTA by 9%, mainly due to the loss of acetic acid.
CChem 47:189 1970 : The total acidity of sour French bread, dough, and starter was determined.
The results were compared conventional bread and dough.
There was ten times more acid in the sour bread than in the conventional bread.
Percentage of acetic acid present in the acid fractions was determined by gas chromatography.
Approximately half of the total acidity of sour French bread and three-fourths of the total acidity of conventional bread was acetic acid.
I found it interesting and very educational.
I want to comment on some of it when I have time.
Some of the procedures that we use are explained by some of this information.
Addition of acid-insoluble gluten proteins significantly reduced loaf volumes I believe that this explains why we use High-gluten flour for the sourdough bread.
We can use regular bread flour, but that will result in a loaf that doesn't have the same volume as bread made with the HG.
Thanks again for these posts.
I have printed the information and places them in my personal baking note book for reference purposes.

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