不同提取方法对杜仲胶提取率及胶特性的影响

Effects of different extraction methods on extraction yield and properties of Eucommia rubber

【目的】研究不同提取方法对杜仲胶得率以及胶热稳定性的影响,以期为杜仲胶的工业化和规模化提取奠定理论基础。【方法】以7月份收集的杜仲翅果皮干粉样(过100目筛)为材料,选用碱浸提法、苯-CH3OH法和酶水解法对杜仲胶进行提取并计算得率;同时利用高温对不同方法提取的杜仲胶进行处理,评价杜仲胶的热稳定性。【结果】以苯-CH3OH法所得杜仲胶其色泽偏暗绿色,形态结构松散且胶块粘稠度较高,但以酶水解法提取的杜仲胶,整体颜色偏蜡黄色,结构致密紧凑且胶块的延展性较好。碱浸提法、苯-CH3OH法和酶水解法提取的杜仲粗胶得率分别为33.29%、9.94%和56.33%,精胶得率分别为1.85%、4.65%和5.36%,杜仲粗胶和精胶得率的不同反映了3种提取方法在进行杜仲胶提取过程的差异性。不同提取法所得杜仲胶热稳定性能的同步热分析仪分析结果表明,3种提取法所得杜仲胶的TG曲线有一定差异,杜仲胶质量损失主要发生在300~470℃范围内,以苯-CH3OH法所提杜仲胶的热稳定性略强于其它两种提取法,但无显著差异,而DSC曲线分析结果显示,3种方法提取杜仲胶的结晶吸热曲线发现杜仲胶的吸热熔融峰只由一个峰型组成,酶水解法提取所得杜仲胶的结晶热焓比另外两种方法提取的略高。【结论】3种方法对杜仲翅果皮干样进行杜仲胶提取,其中以酶水解法提取率最高;杜仲胶性能测定结果表明,3种提取法对杜仲胶热稳定性无显著性影响但对杜仲胶的结晶度有一定影响。综上,酶水解法可作为杜仲胶工业化生产的重要方法。

【Objective】The effects of different extraction methods on the yield and thermal stability were discussed,and the results were expected to lay a theoretical foundation for the industrialization and large-scale extraction of Eucommia rubber.【Method】The dried powder samples of Eucommia ulmoides samara pericarp collected in July(through 100 mesh sieve)was extracted by alkali method,benzene-CH3OH method and enzyme hydrolysis method and the thermal stability of Eucommia rubber was also evaluated by high temperature treatment of Eucommia rubber extracted by these methods.【Result】The color of gutta-percha obtained by benzene-CH3OH method was dark green with loose morphology and high viscosity of the rubber.However,the overall color of gutta-percha extracted by enzymatic hydrolysis method is waxy yellow with compact structure and good ductility of the rubber.The crude yield of Eucommia ulmoides rubber was 33.29%,9.94%and 56.33%by alkali extraction,benzene-CH3OH and enzymatic hydrolysis,while the yield of refined gum was 1.85%,4.65%and 5.36%,respectively.The difference of the yield of crude and refined gutta-percha reflected the difference of the three extraction methods in the extraction process of gutta-percha.Meanwhile,thermal stability of the Eucommia rubber from 3 methods based on simultaneous thermal analyzer(STA)showed the TG curves of Eucommia rubber obtained by the three methods were somewhat different,gutta-percha mass loss occured mainly in the range of 300-470℃,The thermal stability of Eucommia rubber obtained by the benzene-CH3OH method was slightly stronger than that by the other two methods,but there was no significant difference.Additionally,the results of DSC curve analysis showed that three kinds of methods to extract the gutta-percha crystallization heat absorption curve found gutta-percha of endothermic melting peak only consists of a peak type and the enthalpy of crystallization of Eucommia rubber obtained by the enzymatic hydrolysis method was slightly higher than that obtained by the other two extraction methods.【Conclusion】Three methods were used to extract Eucommia rubber from the dried peel of Eucommia ulmoides samara,and the results showed that the three extraction methods had no significant effect on the thermal stability of Eucommia rubber but had some effect on the crystallinity of Eucommia rubber.In conclusion,enzymatic hydrolysis method could be used as an main method for industrial production of Eucommia rubber.