My inadequate memory of small Latin and less Greek reminds me that "apple" in Latin is "malus" -- as in "Ab malus ad ovo" ("From apples to eggs," or as we would say, "From soup to nuts"). "Malic acid" is derived from this, as it is the acid made from apples just as formic acid is made from ants (formus = ant).

I do seem to live in a library....