Yeast Question

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Hello,

    I'm trying a bread recipe that uses a little balsamic vinegar in the
ingredients. My question is will the vinegar kill the yeast or will it just
slow the rising time?



Re: 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


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

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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


Re: Yeast Question
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


Re: Yeast Question

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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.



Re: Yeast Question
On Sun, 05 Jun 2005 02:49:36 GMT, "Vox Humana"

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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,
--
Kenneth

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Re: Yeast Question
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.
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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.<g>.

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<g>
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


Re: Yeast Question

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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



Re: Yeast Question

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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.



Re: Yeast Question
On Sun, 05 Jun 2005 16:29:40 GMT, "Vox Humana"

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Howdy,

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

All the best,
--
Kenneth

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Re: Yeast Question
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


Re: Yeast Question
wrote:

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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,
--
Kenneth

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Re: Yeast Question
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


Re: Yeast Question
wrote:

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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,
--
Kenneth

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Re: Yeast Question

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



Re: Yeast Question
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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 microbes<g>He 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.

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Hi Vox,
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


Re: Yeast Question
wrote:

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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,
--
Kenneth

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Re: Yeast Question
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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
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that the ascorbic acid was used for the purpose for improvement of
yeast performance;
Roy


Re: Yeast Question
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boost yeast   performance.
BTW, the No relation qoute from  that guy( the old microbiologist)
cannot find anything  relevant to find a relation in the addition of
ascorbic acid to the substrate in order to improve yeast performance..
Roy


Re: Yeast Question
wrote:

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Hi again Roy,

As in each of your responses you seem to latch onto
something that I did not say, and then you refute it.

I never said that ascorbic acid is "really needed" to boost
yeast growth.

I never mentioned "industrial application."

I never said that ascorbic acid "was needed" in the brewing
of beer.

I simply said (three times now, I believe) that ascorbic
acid speeds the growth of yeast. I know that to be true from
much that I have read, and from my own experience as a
brewer as well.

If (as your past responses would seem to indicate is likely)
you choose to refute something, you might want to refute
what I have said just above rather than distorting my view
to make for a better target.

All the best,
--
Kenneth

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