超临界CO2脱除构皮木质素的研究

Delignification of mulberry with CO2 supercritical fluid extraction

应用超临界二氧化碳萃取技术脱除构皮木质素,结合4因素3水平的正交试验优化萃取工艺,萃取液的成分分析用气相色谱-质谱联用仪进行.结果表明,影响构皮脱除木质素的因素顺序为温度>压力>夹带剂体积>时间.当萃取温度160℃,萃取压力20 MPa,萃取时间90 min,夹带剂2.0 mL时,构皮中木质素的脱除率最大,为71.62%.且气质联用仪分析得出各个萃取液中均存在含乙氧基和五元环结构的醛、醇和酮类物质,这说明在萃取过程中,构皮中不仅木质素发生了降解,半纤维素碳水化合物和纤维素等其他化合物也发生了降解.借助扫描电子显微镜对超临界萃取前后的构皮进行比较,结果明显观察到经过超临界处理后,样品表面出现许多孔洞,光滑的表面变得粗糙不平.

Supercritical carbon dioxide extraction was used to remove the lignin from the bark.The extraction process was optimized by orthogonal test of 4 factors and 3 levels.The component analysis was carried out by gas chromatography-mass spectrometry(GC-MS).The results showed that the sequence of factors affecting lignin removal from bark was temperature>pressure>entrainer volume>time.The lignin removal rate was 71.62%when the extraction temperature was 160℃,the extraction pressure was 20 MPa,the extraction time was 90 min and the entrainer was 2.0 mL.The results of GC-MS analysis showed that aldehydes,alcohols and ketones containing ethoxyl and pentacyclic structure existed in all extracts,which indicated that not only lignin but also cellulose and hemicellulose carbohydrates were degraded during the extraction process.Scanning electron microscopy was used to compare the skin texture before and after supercritical extraction.The results showed that after supercritical extraction,many holes appeared on the surface of the sample,and the smooth surface became rough and uneven.