The following is the list of ingredients in a commercial sourdough base
which some bakers use in their "sourdough" bread. This mix comprises 25% of
the flour component to which ordinary yeast is added.

Flour, vegetable oil shortening, dried sour dough, malted barley and corn,
citric acid, soy lecithin, artificial flavour, salt, fumaric acid, soybean
oil, ascorbic acid, sugar, sodium steroyl-2-lactylate, sodium chloride, corn
flour, calcium sulfate, ammonium chloride, azodicarbonomide

It is supposed to give that authentic SF flavor!! Aren't you glad that you
make your own?

Graham