Lemonade mix was based on citric acid. Fruit-Fresh had
both citric and ascorbic acid.

Ascorbic acid is not used for the purpose of an acidulant in such
juice mix formulations but as to add some nutritional value in form of
vitamin C.

The real problem with citric acid is its more water soluble so when it
dissolves in the aqueous phase it will dissociate into citrate ion, the
more water there is in the creams the less will be the resulting
acidity. Therefore if you taste a crystal of citric acid is more sour
than a solution of it. As it's the matter of solute concentration.
On the other hand fumaric acid is less soluble and there is more
distinctive tartness .
I made some sour gum drops , snakes and gummy bears and I used a blend
of citric acid and fumaric, sometimes with malic acid and it resulted
in a persistent but fruity sour taste.


I'm not familar with fumaric acid but I'll look for some.
(But I draw the line at trying hydrochloric, sulfuric,
nitric or muriatic acid.)

Yes you better keep away from inorganic acids such as sulfuric and
specially nitric acid. If you combine them in proper proportion and
add to the sugar you might end with sugar polynitrates which are
powerful explosives!
You are making a bomb instead of your desired confections!
Then ATF and FBI will be watching you every time you make candies with
those acid Nitric /sulfuric acid blends< LOL>
Besides the nitrate ion can be reduced in the gut to nitrite which will
pickle your customers innards into cured sausage casings <LO,L>
Another things nitric acid might combine with your stomach hydrochloric
acid which can form a dilute aqua regia used for cleaning jewelry<LOL>


Meanwhile muriatic acid in dilute quantities is found in the stomach(
as mentioned earlier) so its not a poison in dilute concentrations..
In fact its used in the manufacture of glucose syrups as well as large
scale manufacture of invert syrups.
The main fault of the dilute hydrochloric acid is it has non appetizing
taste.