Enzymatic assay technique for the determination of aspartame

An enzymatic assay technique was developed for the determination of the artificial sweetener aspartame. The peptide bond of aspartame was first cleaved by peptidase to release aspartic acid. In the presence of α-ketoglutarate, aspartic acid was then transaminated by aspartate aminotransferase to glutamate. The reaction was monitored by following the oxygen consumption during the enzymatic oxidation of glutamate by glutamate oxidase. A linear relationship between oxygen consumption and aspartame concentration up to 200 μM was obtained. The assay technique was applicable to the determination of aspartame in a variety of dietary food products. The results obtained agreed well with those determined by liquid chromatography and those reported by the product manufacturers.