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.
>"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."
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 *******ized 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