Malic acid

Acidulant, flavoring: Fruit-flavored drinks, candy, lemon-flavored ice-tea mix, ice cream, preserves.
L-Malic acid is an important metabolite present in all living cells and is abundant in apples. It is sometimes called "apple acid." The food industry uses malic acid as an acidulant and flavoring agent in fruit-flavored drinks, candy, lemon-flavored ice-tea mix, ice cream, and preserves.

While adults can probably utilize D-malic acid (the unnatural form), infants may not, so synthetic DL-malic acid should not be added to baby food.