甜叶菊有效成分动态积累分析及水提液澄清工艺初探

Dynamic Accumulation Analysis on the Effective Components and Preliminary Clarification Process Study on the Water Extract of Stevia rebaudiana Bertoni

为了探索甜叶菊有效成分积累规律,本研究采用高效液相色谱法测定了在2018年7月24日至10月16日甜叶菊谱星6号叶中甜菊糖苷、绿原酸类和类黄酮含量的变化;采用壳聚糖季铵盐、壳聚糖盐酸盐、白色聚合氯化铝、黄色聚合氯化铝、硫酸亚铁+氢氧化钙等5种絮凝剂对甜叶菊水提液进行澄清处理,通过分析水提液澄清率及3种甜菊糖苷和6种绿原酸类在澄清液中的保留率,探索甜叶菊水提液的澄清方法。结果表明,甜叶菊叶片生物量积累呈上升趋势;各甜菊糖苷的含量变化幅度小;绿原酸类及类黄酮成分的积累与生长期密切相关,含量呈现降低-升高-稳定-降低的动态变化趋势。甜菊糖苷、绿原酸类和类黄酮的含量在9月18日至10月2日时段达到最高值,分别为168.74、73.78和14.88 mg/g。结合产量和有效成分两方面因素,确定新疆巴州甜叶菊最佳采收期为9月中旬至10月初。不同的絮凝剂对甜叶菊水提液的澄清效果不同,采用壳聚糖盐酸盐絮凝处理水提液中9种有效成分的保留率最高,以0.45 g/L壳聚糖盐酸盐在45℃条件下澄清率达到89.39%。壳聚糖盐酸盐可以作为适宜的絮凝剂应用于甜叶菊水提液中甜菊糖苷和绿原酸类的分离纯化。

To explore the general law of dynamic accumulation of the effective components in Stevia rebaudiana Bertoni,the contents of steviol glycosides, chlorogenic acids and flavonoids were investigated during the growth period. The leaf samples of Stevia rebaudiana Bertoni cultivar Puxing 6 from July 24 to October 16, 2018 were used as the subjects of high performance liquid chromatography analysis. In order to study clarification methods through analyzing the clarification rate and retention rate of three steviol glycosides and six chlorogenic acids, water extract of Stevia rebaudiana Bertoni was clarified by using five kinds of flocculants such as chitosan hydrochloride, chitosan quaternary ammonium, polyaluminum chloride(white), polyaluminum chloride(yellow) and ferrous sulfate plus calcium hydroxide. The results indicated that biomass showed an increased trend, and the contents of steviol glycosides showed a small fluctuation. The accumulation of chlorogenic acids and flavonoids was closely related to the growth period, and the contents presented decreased-increasedstabilized-decreased trend. The contents of steviol glycosides, chlorogenic acids and flavonoids reached the highest value from September 18 to October 2, which were 168.74, 73.78 and 14.88 mg/g respectively. According to the production and effective components, the optimal harvest time of Stevia rebaudiana Bertoni in Bazhou district of Xinjiang province should be from mid-September to early October. Different flocculants presented different clarification effects on water extract, and flocculating treatment of chitosan hydrochloride showed the highest retention rate of nine indicative components. The optimum condition obtained for chitosan hydrochloride were the dosage of 0.45 g/L and 45 ℃ temperature, and a clarification rate reached 89.39%. Chitosan hydrochloride could be used as a suitable flocculant for separation and purification of steviol glycosides and chlorogenic acids in water extract of Stevia rebaudiana Bertoni.