On-line monitoring of stevioside sweetener hydrolysis to steviol in acidic aqueous solutions

Stevioside, a potent sweetener obtained from leaves of Stevia rebaudiana (Bertoni), is the glycone of steviol. However, despite its natural origin, there has been concern about stevioside toxicity due to hydrolysis to the carcinogenic steviol. To approve it as an additive, the FAO/WHO committee on food additives has required further information about hydrolytic stability of the steviol glycoside in acidic foods and beverages. In this study, aqueous solutions of stevioside at different pH values were monitored in real time by direct infusion ESI-MS. Owing to the high speed and sensitivity of ESI-MS monitoring, fast hydrolysis of the stevioside molecule to steviol in aqueous acidic solutions was observed, particularly in acidic juices. (C) 2011 Elsevier Ltd. All rights reserved.