As an important sweetener, aspartame is widely used in pharmaceutical processing and food processing. The ester bond of aspartame in aqueous solution can be hydrolyzed to produce aspartyl phenylalanine and methanol under certain temperature and acidic pH conditions. Under neutral, alkaline (pH>7) or heated conditions, or through cyclization to eliminate methanol to form cyclic aspartyl phenylalanine. Eventually, aspartyl phenylalanine will continue to be hydrolyzed to produce two separate amino acids-aspartic acid and phenylalanine. In peptide synthesis, such short peptides are generally synthesized under liquid conditions.