Yeast Question

Bernard Clayton mentions in his book on bread that (powdered) ascorbic acid is sometimes mixed with flour. He says the it strengthens the dough and thus gives the loaf greater rise. I would assume that like with other additives it is possible to overdo it. BobbiJo

Nope,,,,,in fact there are bread recipes used by the baking industry where vinegar is even added as a bread preservative.

I have no idea whatis mean by the word 'little' to you;therefore you better test your recipe first and see how the fermentation time changes with the little amount of vinger is added to your dough. In my experience with vinegars in bread assuming the amount of acid is very little it will not affect the fermentation rate, so ther recipe remains the same but if you add enough that a distint acidic taste will be noted in the bread , you will need to increase your yeast level to

100% to get the same fermentation and proofing time. Roy

While looking for recipe in King Arthur Baker's Companion, I came across a more detailed answer to your question. "Adding a tablespoon of orange juice concentrate or vinegar or a pinch of ascorbic acid to bread dough will aid in its rising. Yeast loves to grow in an acidic environment. .....A little extra acid works particularly well in rich sweet doughs, which often rise very slowly. In a side-by-side test, kutchen with ascorbic acid rose 50 percent higher than plain kuchen in the same amount of time." BobbiJo

Shirley Corriher recommends adding ascorbic acid to your yeast dough in "Cookwise." Her method involved crushing a vitamin C tablet. Since "Fruit Fresh" is ascorbic acid and is already in powder form, I just add about a teaspoon - when I remember.

While looking for recipe in King Arthur Baker's Companion, I came across a more detailed answer to your question I did not touch more of the detail as that might intimidate the OP who I presume has not a slightest idea what he is up to. But now you seem to know more then there is a need for more explanation.

I disagree with that,, as its technically wrong. It confirms that the 'venerable' Mr Clayton is pretty ignorant in bread chemistry. But still had the courage to expound such erroneous statement. Oh well, you can still read his book but don't swallow everything what he say as he does not know much about it! In the past I had browsed his book but found it suited to the mentality of the school children and not for the adult IMO..

I have disagreed a lot of his recipes as he bastardized the French baking system by injecting American ideas which are alien from the original way of French baking system. It is just a sad fact that the American public who are the vigorous readers of his book swallowed everything...literally ....hook,line and sinker Anyway Hmmn so you want to play with dough chemistry?.....let's see what you got.... Technically The amount of ascorbic acid in the dough is miniscule if compared to the amount of vinegar in the dough to confer beneficial effects. Think about it the required dosage of ascorbic acid is up to 200 mg per kilogram of flour; where as the amount of vinegar added to the dough amounts to 5-10% of the flour weight or 50-100 grams depending upon the concentration. of acetic acid in the vinegar. The addition of ascorbic acid do not change the pH of the dough but the addition of vinegar surely will. That is why I am cautious about the question of the original poster, he does not say how much and what strength is his vinegar that he want to incorporate to the dough. The biggest fault of any hobbyist is that they are imprecise and inaccurate in their measurements and ingredient description. Who knows how much is little to that poster and what is the concentration of acetic acid in his particular bottle of balsamic vinegar. BTW, regarding your comments that adding orange juice will confer the same result as adding vinegar, that is not true. Chemically speaking acetic acid and citric acid had different ionization and pH and pKA values, therefore performance wise they are different. I can add orange juice to my dough and I don't need to worry much about yeast activity . But its a totally different matter with vinegar which has an inhibiting effect on yeast activity. that is why I asked the OP to act with caution and to test if his recipe is suited for modification. Now going back to ascorbic acid ... that substance has an improving effect on the dough due to the oxidation reduction process that interacts with the gluten proteins to confer some dough strengthening effect.which results in the dramatic improvement of dough quality. Whereas excess acidity as conferred by adding considerable amounts of acids such as acetic acid will weaken the gluten making it mellow and extensible(that is the principle being used in the preparation of puff pastry by acidifying the dough with lemon juice is one application). Now you assume that vinegar acts the same like ascorbic acid which DOES NOT!. Now regarding your comment that dough needs acidity that is correct but depending on the degree of acidity and the type of breadmaking you are using; if you are just a plain yeast raised dough tthat is just in the vicinity of pH5 but for sourdough that can goes down to pH4. Then there is another difference due to the acidity of the latter the fermentation and proofing is much slower than the normal yeast raised dough.. So you had to think about the deeper aspects of acidifying the dough, either by direct addition with acidulants or by natural fermentation that occurs in sourdough and that you can safely state that acidity should not be taken for granted in breadmaking in the same way that aspirin is not the panacea for sickness. Therefore better think deeper about dough acidity according to the different means of breadmaking and see the difference how acidity influences dough behavior. Roy

A statement like that bothers me. They are saying that ascorbic acid, acetic acid and citric acid are all the same chemically and have the same strength. I happen to like the book that is quoted, but a statement like that makes me question it. Janet

In addition, I believe that the ascorbic acid (vitamin C) was recommended not to change the pH of the dough, but as a nutrient for the yeast.

Howdy,

Many flour suppliers add ascorbic acid to their products. Check the label.

All the best,

Well ...its likely that the pH will change during the fermentation process by a certain value( but not much,i.e. in fractional/decimal units))..Measuring titratable acidity is one of the quality control method used in industrial baking and is partly based on that premise.. But in the presence of other acids ( e.g. acetic acid)the change in pH is considerable. Now regarding yeast nutrient, Ascorbic acids does not act the same way as the ammonium , ,phosphates and other mineral ions which invigorate the yeast cell.What ever other growth factors the yeast needs it just synthesis itself as long as the required nutrient precursors are present, but vitamin C is not one of them. It is a fact that (even now) a lot of bakers still believed in that idea that the improving effect of vitamic C is due to its effect on yeast metabolism which is not true. Yes the dough matures faster in its presence( vitamin C)( in the same way that higher levels of ethylene accelerates fruit ripening) but its effect is on the gluten proteins and never on the yeast cells. You can make bread without vitaminc but that needs extended fermentation process as dough matures by slow biochemical means through enzymatic and chemical oxidations process. If vitamin C is purposely added then that will change the reaction rate( dough maturation) by the process in which ascorbic acid is reduced enzymatically to dehydroascorbic acid which had the active oxidizing effect on the flour protein structure in particular the amino acid linkages which affect the protein conformation resulting it to tighten creating what is known as dough strengthening effect that is beneficial to the dough performance. So what ever is the type of breadmaking process being applied vitamin C does not take part in the yeast metabolism equation; rather on the flour proteins itself. Roy

Howdy,

That would be enough ascorbic acid for something on the order of 1000 pounds of flour. The appropriate amount is miniscule (and, I mentioned earlier, is often already in the flour.)

All the best,

Hi Roy,

I know little about yeast metabolism, but I do know that ascorbic acid radically increases the growth of yeast used in brewing beer.

All the best,

Hmnn... I have to check the biochemistry of such idea later. when I get home. IIRC Beer brewing and breadmaking use a general strain of yeast which belongs to , saccharomyces cereviseae , but which is subgrouped into specific strains for various brews with accompanying specific nutrtional requirements . . But to my knowledge I am not aware that brewers in industrial scale pitch in ascorbic acid for such purpose.. Roy

Interesting. Years ago, I got some whole wheat flour from a local mill, and they recommended adding a tbsp of lemon juice to make the bread lighter. I've been doing this, figuring they knew whereof they spoke, but until now I never knew why. This is an interesting posting.

H.

Hi again,

I said nothing about brewing on "in industrial scale." I merely said that ascorbic acid increases yeast growth in brewing. I believe that it does the same in baking.

All the best,

Isn't ascorbic acid a component of some instant dry yeast products?

Hello Kenneth, I have derived the biochemical needs of yeast growth ether for baking or brewing applications but I cannot find any mechanism where ascorbic acid fits in. Most of the vitamin based growth factors that come to play are B vitamins( thiamn,biotin,panthotenic acid, nicotinic acid, riboflavin and inositol and not a trace of ascorbic acid comes into the equation. I looked also in my reference for yeast technology . yeast chemistry and biology there was never any mention of such vitamin C as part of the substances that can promote yeast growth. See these relevant references Reed ,G and Nagowithana T,W, Yeast Technology by Avi publishing and Cook A,H. The Chemistry and Biology of Yeast, Academic Press This confirms that vitamin C is never needed by yeast in its growth and metabolism Therefore who ever he is, a home brewer perhaps, who claimed such 'radical way' of improving his brewing process may have reach a conclusion from an erroneous assumption thinking that vitamin C being needed by human is also needed by microbesHe may have overlooked other relevant factors that promote yeast activity and just blamed it on vitamin C. If you can present any reference so that I can check it then that would be interesting.

Any instant yeast that contains vitamin C is not added for reasons to improve yeast stability, but to contribute to the improvement of baking performance making their yeast better than competing brands who does not have it. Roy

Hi Roy,

As before, you seem to be critiquing something that I never said.

I never said that among yeast "needs" was ascorbic acid. I said that ascorbic acid is widely used in brewing to speed the growth of yeast. I added that I believe that if it has that effect on the yeasts used in brewing, it is likely to have the same effect on the yeasts used in baking.

All the best,

Hi again Roy,

I read your comments above with a bit more care, and have something to offer:

you will find many scientific papers on the effects ofascorbic acid on the growth rate of yeasts. All the best,

Hi Kenneth,

As I had stated in my earlier post, I could not find any evidence that ascorbic acid is really needed to boost the yeast growth in whatever application; either baking and brewing, I looked also at other industrial application of yeast such as in the manufacture of wine and spirits and even fodder yeast and there was not trace of evidence that ascorbic acid was ever added to speed up yeast performance. Just recently I called an old friend who has worked previously as a microbiologist in the yeast plant and earlier in the brewing industry and asked him about the ascorbic acid to speed yeast growth either in laboratory culture slant or even to enhance yeast fermentation in beer. He said to me never in his experience and knowledge that ascorbic acid was needed for such purpose; I even related to him the papers you linked which he checked but he called me back and just said and upon browsing on it and he was insistent, saying THEIR IS STILL NO RELATION. This again corroborate my analysis and references that its not required to boost yeast activity

that the ascorbic acid was used for the purpose for improvement of yeast performance; Roy