Let's see here. There are a minimum of 3 grams of malik acid in a liter of apple juice (http://www.curezone.com/forums/fm.asp?i=167713#i). It takes 8 apples to make an 8 ounce glass of juice (http://www.healthychild.net/articles/na22juice.html), or one apple per ounce. Since there are about 33.8 ounces in a liter (1 liter = 33.8140227 US fluid ounces), that would mean about 33.8 apples to make the liter. So the equation would be:
3 grams / 33.8 apples = 0.08875 grams per apple or,
About 88.75 mg of malik acid per apple
Since the 3 gram figure was stated as a minimum, it would probably be pretty safe to say around 90 mg of malik acid per apple.