Malic Acid is a naturally occurring acid found in natural fruits like apples, cherries and peaches.
Malic Acid is used in a variety of products. It is often used in sour tasting foods.
In wine-making, malic acid is sometimes used to adjust the acidity of wine to help bring dull fruit flavors to the front of the wine as well as provide a healthy environment to ensure full fermentation.
Many report that it is useful in adjusting the tartness of cider.