Aspartame is a methyl ester of dipeptides consisting of aspartic acid and phenylalanine. It was accidentally discovered in 1965 by the chemist James M. Schlatter while working on an antiulcer drug (Walters, 1991). Aspartame is 160—220 times sweeter than sucrose and is used as arti­ficial sweetener in foods and beverages. Aspartame is pro­duced by coupling microbial fermentation and synthesis. Phenylalanine and aspartic acid are produced by microbi­al fermentation and phenylalanine is reacted with meth­anol to form the methyl ester. Aspartic acid is also treated in such a way as to protect active sites by benzyl rings. Then the modified amino acids are mixed in a reac­tion tank at appropriate temperatures to get aspartame in­termediates (Figure 19.2). It is further treated with acetic acid, purified, crystallized and powdered to produce aspartame. Methods for direct enzymatic synthesis and chemical synthesis are also reported.