Stevioside and Stevia-sweetener in food: application, stability and interaction with food ingredients

The stability of the natural sweetener stevioside during different processing and storage conditions as well as the effects of its interaction with water-soluble vitamins, food relevant organic acids and other common low calorie sweeteners and its application in coffee and tea beverages were evaluated. Incubation of the solid sweetener stevioside at elevated temperatures for 1 h showed good stability up to 120A degrees C, whilst at temperatures exceeding 140A degrees C forced decomposition was noticed. In aqueous solutions stevioside is remarkable stable in a pH range 2-10 under thermal treatment up to 80A degrees C, however, under strong acidic conditions (pH 1) a significant decrease in the stevioside concentration was detected. Up to 4 h incubation of stevioside with individual water-soluble vitamins in aqueous solution at 80A degrees C showed no significant changes in regard to stevioside and the B-vitamins, whereas a protective effect of stevioside on the degradation of ascorbic acid was observed resulting in a significant delayed degradation rate. In the presence of other individual low calorie sweeteners practically no interaction was found at room temperature after 4 months incubation in aqueous media. Stability studies of stevioside in solutions of organic acids showed a tendency towards enhanced decomposition of the sweetener at lower pH values depending on the acidic medium. In a stevioside-sweetened coffee and tea beverage, practically, no significant chances neither in caffeine content nor in stevioside content could be noticed. Furthermore an overview of already performed studies in literature about the Stevia-sweetener stevioside and rebaudioside A is given.