Relative sweetness of rebaudioside M at different sucrose equivalence levels and pH conditions

Purpose: This study compared the relative sweetness (RS) of rebaudioside M (Reb-M) across different sucrose equivalence values (SEVs) (2, 5, 7, 8.5, and 10% sucrose) and pH conditions to assess its suitability as a natural alternative sweetener in acidic beverage systems. Methods: The RS was measured using a two-alternative forced-choice (2-AFC) test under a pH-unadjusted condition (AQ) and under an acidic condition (AC) adjusted to pH 3.0 with citric acid. Two commercial Reb-M products (Reb-M1 and Reb-M2) from different manufacturers were tested. The RS values were estimated using regression analyses of concentration-response curves constructed from 2-AFC tests. Results: Both Reb-M1 and Reb-M2 showed a gradual decrease in RS as the SEV was increased in AQ and AC. At all SEV levels, the RS values were higher under AC than under AQ. The acid treatment increased RS by 4.2%∼9.9% at SEV 2% and by 19.5%∼43.5% at SEV 5% and above. These results suggest that acidity enhances the perceived sweetness of Reb-M, particularly at higher concentrations, partially mitigating the decrease in RS observed at high SEV levels. Conclusion: Reb-M showed greater sweetness efficiency under acidic conditions, especially at mid- to high-sweetness levels, highlighting its potential to replace sucrose in acidic beverage formulations. More study on their sensory profiles and consumer acceptance under varying SEV and pH conditions is needed to confirm the practical applicability of Reb-M.