不同提取方法对烟草纤维素微观结构的影响

Effects of different extraction methods on microstructure of tobacco cellulose

为探究不同提取方法对烟草纤维素微观结构的影响,采用中性洗涤剂法、酸性洗涤剂法、酸性水解法、碱液分离法分别对烤烟和香料烟烟叶样品中的纤维素进行提取;利用交叉极化结合魔角旋转13C核磁共振(CP/MAS 13C NMR)技术对不同方法获得的烟草纤维素进行微观结构表征;对比分析4种方法的得率及提取所得烟草纤维素的纯度,并通过对NMR光谱吸收峰拟合,得到烟草纤维素晶型及分布、结晶度和原纤尺寸等结构信息。结果表明:①中性洗涤剂法提取所得烟草纤维素纯度高于其他3种方法。②4种提取方法所获烟草纤维素晶型相同,均以纤维素Iβ晶型为主,但晶型分布存在明显差异。③4种提取方法中,中性洗涤剂法所获烟草纤维素结晶度最大,且基原纤尺寸和基原纤聚集束尺寸最大。对比其他3种方法,中性洗涤剂法对烟草纤维素微观结构影响最小。因此,中性洗涤剂法适合作为烟草纤维素微观结构研究中纤维素的提取方法。

In order to investigate the effects of different extraction methods on the microstructure of tobacco cellulose,the cellulose of flue-cured and oriental tobacco leaves was extracted by neutral detergent method,acid detergent method,acid hydrolysis method and alkali treatment method.The microstructure of tobacco cellulose extracted by different methods was characterized by solid-state cross-polarization magic angle spinning carbon-13 nuclear magnetic resonance(CP/MAS 13C NMR).The yields and purity of tobacco cellulose extracted by the four methods were comparatively analyzed.The structural information such as crystal form and distribution,crystallinity and fibril size of tobacco cellulose were obtained by fitting the absorption peaks of NMR spectra.The results showed that:1)The purity of tobacco cellulose extracted by neutral detergent method was higher than the other three methods.2)The tobacco cellulose extracted by the four methods had the same crystal form with the dominant cellulose form of Iβcrystal,however the crystal form distribution was significantly different.3)Among the four extraction methods,the cellulose extracted by neutral detergent method had the highest crystallinity,and the sizes of elementary fibrils and elementary fibril aggregates were the largest.Compared with the other three methods,the influence of neutral detergent method on the microstructure of tobacco cellulose was the slightest.Thus,for the study of tobacco cellulose microstructure,neutral detergent method is a suitable cellulose extraction method.