The term ACID APPLE is composed of three words: AMINO, BORIC, and OLEIC. Amino is an organic compound containing nitrogen and hydrogen, which is essential for the formation of proteins. Boric acid is a weak acid that is used in many industrial and household products. Oleic acid is a monounsaturated fatty acid found in many plant and animal fats. Together, these three words form the term ACID APPLE, which is often used to describe a sour or tart flavor.