Gardana Claudio, Simonetti Paolo, Canzi Enrica, Zanchi Raffaella, Pietta Piergiorgio
Department of Food Science and Microbiology, Division of Human Nutrition, University of Milan, Via Celoria 2, 20133 Milan, Italy.
J Agric Food Chem. 2003 Oct 22;51(22):6618-22. doi: 10.1021/jf0303619.
Stevia rebaudiana standardized extracts (SSEs) are used as natural sweeteners or dietary supplements in different countries for their content of stevioside or rebaudioside A. These compounds possess up to 250 times the sweetness intensity of sucrose, and they are noncaloric and noncariogenic sweeteners. The aim of this study was to investigate the in vitro transformation of stevioside and rebaudioside A after incubation with human microflora, the influence of these sweeteners on human microbial fecal community and which specific groups metabolize preferentially stevioside and rebaudioside A. The experiments were carried out under strict anaerobic conditions in batch cultures inoculated with mixed fecal bacteria from volunteers. The hydrolysis was monitored by HPLC coupled to photodiode array and mass spectrometric detectors. Isolated bacterial strains from fecal materials incubated in selective broths were added to stevioside and rebaudioside A. These sweeteners were completely hydrolyzed to their aglycon steviol in 10 and 24 h, respectively. Interestingly, the human intestinal microflora was not able to degrade steviol. Furthermore, stevioside and rebaudioside A did not significantly influence the composition of fecal cultures; among the selected intestinal groups, bacteroides were the most efficient in hydrolyzing Stevia sweeteners to steviol.
甜叶菊标准化提取物（SSEs）因其甜菊糖苷或莱鲍迪苷A的含量，在不同国家被用作天然甜味剂或膳食补充剂。这些化合物的甜度强度是蔗糖的250倍，且它们是无热量和非致龋性甜味剂。本研究的目的是调查甜菊糖苷和莱鲍迪苷A与人微生物群孵育后的体外转化情况、这些甜味剂对人类微生物粪便群落的影响以及哪些特定菌群优先代谢甜菊糖苷和莱鲍迪苷A。实验在严格厌氧条件下，于接种了志愿者混合粪便细菌的分批培养物中进行。通过与光电二极管阵列和质谱检测器联用的高效液相色谱法监测水解情况。将在选择性肉汤中孵育的粪便材料中分离出的细菌菌株添加到甜菊糖苷和莱鲍迪苷A中。这些甜味剂分别在10小时和24小时内完全水解为它们的苷元甜菊醇。有趣的是，人类肠道微生物群无法降解甜菊醇。此外，甜菊糖苷和莱鲍迪苷A对粪便培养物的组成没有显著影响；在所选的肠道菌群中，拟杆菌在将甜叶菊甜味剂水解为甜菊醇方面效率最高。
