White crystalline flakes or crystalline powder. Slightly bitter. Odorless. The sublimation temperature is 168-170℃. It is an essential amino acid and is necessary for the normal development of infants and the nitrogen balance of adults. There are four isomers, and only the L-form has physiological effects. Excessive consumption will have an antagonistic effect with leucine and hinder development. Adult men need 1.3g/100ml.