Wölwer-Rieck Ursula, Tomberg Werner, Wawrzun Andreas
Department of Nutrition and Food Sciences, Food Chemistry/Bioanalytics, Rheinische Friedrich-Wilhelms-Universität Bonn, Endenicher Allee 11-13, 53115 Bonn, Germany.
J Agric Food Chem. 2010 Dec 8;58(23):12216-20. doi: 10.1021/jf102894v. Epub 2010 Nov 10.
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).
在80℃下储存24、48和72小时后，对添加了甜菊糖苷或莱鲍迪苷A的不同软饮料样品中两种甜菊糖苷甜菊糖苷和莱鲍迪苷A的稳定性以及糖苷配基甜菊醇的可能形成情况进行了分析。观察到降解率高达70%，且甜菊糖苷比莱鲍迪苷A更不稳定。采用高效液相色谱-紫外检测法（UV-HPLC）在HILIC分析柱上对甜菊糖苷和莱鲍迪苷A及其降解产物进行分析，并通过液相色谱-电喷雾电离质谱法（LC-ESI-MS(n)）在负离子模式下确认降解产物的身份。开发了一种使用C18分析柱的UV-HPLC方法，以排除糖苷配基甜菊醇的存在，甜菊醇在使用敏感鼠伤寒沙门氏菌TM677菌株的正向突变试验中呈阳性反应。该方法对甜菊醇的回收率在95.9%至109.2%之间，校准曲线在1至100μg/mL范围内呈线性，R(2)=0.9999。检测限为1μg/mL。通过LC-ESI-MS(n)确认后的检测限为6ng/mL。通过UV-HPLC和LC-ESI-MS(n)可以明确确认降解样品中不存在甜菊醇。
