Abstract: The calorimetric curves of sweetener, standards and aspartame/lactose mixtures indicated displacement of transition temperatures in sweetener for smaller temperatures, decreasing the thermal stability. The images in the photovisual system confirmed the displacement of transition temperatures in sweetener and binary mixtures. The brown coloration in smaller temperatures has suggested interaction of aspartame with lactose similar the Maillard’s reaction. These techniques allow a rapid evaluation of possible interactions between raw material and excipients.