Aspartame Degradation Kinetics as Affected by pH in Intermediate and Low Moisture Food Systems

Kinetics of aspartame degradation in low to intermediate moisture systems were evaluated by incorporating aspartame into agar/micro-crystalline cellulose model systems. They were prepared at pH 3, 5, and 7, equilibrated after freeze-drying to three water activities (0.34, 0.56, and 0.66), and stored at 25 to 45°C. Aspartame in such systems was most stable at pH 5 and became less stable as pH decreased or increased. As the molar buffer salt concentration increased, the rate of aspartame degradation increased. The activation energy ranged from 23 to 36 kcal/mole.