Investigations on the stability of stevioside and rebaudioside a in soft drinks.
The stability of the two steviol glycosides stevioside and rebaudioside A and the possible formation of the aglycon steviol in different soft drinks were analyzed in samples spiked with stevioside or rebaudioside A after 24, 48, and 72 h storage times at 80 °C. Degradation of up to 70% was observed, and stevioside was less stable than rebaudioside A. Stevioside and rebaudioside A and their degradation products were analyzed by high-performance liquid chromatography with ultraviolet detection (UV-HPLC) on a HILIC analytical column, and the identity of the degradation products was confirmed by liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS(n)) in negative mode. A UV-HPLC method was developed using a C18 analytical column to exclude the presence of the aglycon steviol, which gave a positive response in the forward mutation assay using the sensitive Salmonella typhimurium TM677 strain. The recoveries of steviol with this method ranged from 95.9 to 109.2%, and the calibration curves were linear from 1 to 100 μg/mL with R(2) = 0.9999. The limit of detection was 1 μg/mL. Confirmation by LC-ESI-MS(n) resulted in a LOD of 6 ng/mL. The absence of steviol in the degraded samples could be unambiguously confirmed by UV-HPLC and by LC-ESI-MS(n).
Department of Nutrition and Food Sciences, Food Chemistry/Bioanalytics, Rheinische Friedrich-Wilhelms-Universität Bonn, Endenicher Allee 11-13, 53115 Bonn, Germany.
Ursula
U
Wölwer-Rieck
Werner
W
Tomberg
Andreas
A
Wawrzun
D002253:Carbonated Beverages / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid; D045786:Diterpenes, Kaurane / Q000737:chemistry*; D005503:Food Additives / Q000737:chemistry*; D005960:Glucosides / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization; D013549:Sweetening Agents / Q000737:chemistry*
D045786:Diterpenes, Kaurane; D005503:Food Additives; D005960:Glucosides; D013549:Sweetening Agents; C012043:stevioside; C025474:rebaudioside A