Stability of rebaudioside A under acidic conditions and its degradation products

Stability of rebaudioside A, a sweet component of Stevia rebaudiana was studied covering a typical pH range 2.8-4.2 that simulated both relevant and extreme beverage storage conditions. Thus, rebaudioside A was evaluated in mock beverage solutions by simulating formulations used in commercial cola soft drinks (pH 2.8 and pH 3.2), lemon-lime soft drinks (pH 3.8), and root beer soft drinks (pH 4.2) but lacking the flavor components. The mock beverage samples, formulated at ~ 500 mg/l were subjected to various temperature conditions (5, 20, 30, and 40 °C) for 26-weeks at each pH. Samples were analyzed at scheduled intervals throughout the 26-week period for rebaudioside A, its known impurities and degradation products. Experimental results indicated that rebaudioside A yielded six minor degradation compounds whose structural characterization was performed on the basis of 1D (1H, 13C) and 2D (COSY, HSQC, HMBC) NMR, HRMS, MS/MS spectral data as well as enzymatic and acid hydrolysis studies.

► Stability of rebaudioside A, a sweet component of Stevia rebaudiana was studied by covering a typical pH range 2.8-4.2 that simulated both relevant and extreme beverage storage conditions. ► Thus, rebaudioside A was evaluated in carbonated mock beverage solutions by simulating formulations used in commercial cola soft drinks (pH 2.8 and pH 3.2), lemon-lime soft drinks (pH 3.8), and root beer soft drinks (pH 4.2) but lacking the flavor components. ► The mock beverage samples were subjected to various temperature conditions (5, 20, 30, and 40 °C) for 26-weeks at each pH. ► Samples were analyzed at scheduled intervals throughout the 26-week period for rebaudioside A, its known impurities and degradation products. ► Experimental results indicated that rebaudioside A yielded six minor degradation compounds whose structural characterization was performed on the basis of 1D (1H, 13C) and 2D (COSY, HSQC, HMBC) NMR, HRMS, MS/MS spectral data as well as enzymatic and acid hydrolysis studies.