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首页> 外文期刊>Journal of Applied Polymer Science >Structure and thermal stability of polysaccharide fractions extracted from the ultrasonic irradiated and cold alkali pretreated bamboo
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Structure and thermal stability of polysaccharide fractions extracted from the ultrasonic irradiated and cold alkali pretreated bamboo

机译：超声辐照和冷碱预处理竹中提取的多糖组分的结构和热稳定性

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摘要

Polysaccharide fractions were extracted from partially delignified bamboo (Neosinocalamus affinis) culms pretreated with ultrasonic irradiation for varied times and cold sodium hydroxide/urea solution, and their structure and thermal stability were comparatively characterized. In this case, ball-milled bamboo culms were treated with ultrasonic irradiation for varied times (0, 5, 15, and 25 min), dissolved with 7% sodium hydroxide/12% urea solution at -12°C, and then extracted with ethanol and dioxane to obtain partially delignified solid fractions. Subsequently, the solid fractions were subjected to be extracted with dimethyl sulfoxide followed by precipitation in ethanol and yielded the polysaccharide fractions. Sugar analysis indicated that the total sugar content increased from 60.63% in the polysaccharide fraction prepared without ultrasonic irradiation to 81.26% in the polysaccharide fraction prepared with an ultrasonic irradiation time of 25 min. Glucose (～ 50-55%) was the major sugar component, and xylose (～ 41-44%) was the second major sugar in polysaccharide fractions in all cases. Spectroscopy (FTIR, ~1H-NMR, ~(13)C-NMR, and HSQC) analysis suggested that the polysaccharide fractions were mainly composed of (1→4)-linked α-D-glucan from amylose and (1→4)-linked β-D-xylan attached with minor amounts of branched sugars from hemicelluloses. In addition, thermal analysis showed that the main degradation stage of the polysaccharide fractions occurred between 210 and 320°C. Compared to the polysaccharide fraction prepared without ultrasonic irradiation, the polysaccharide fraction prepared with ultrasonic irradiation had a slightly lower thermal stability.
机译：从部分脱木质素的竹子（Neosinocalamus affinis）茎中提取多糖，并经超声辐照不同时间和冷氢氧化钠/尿素溶液预处理，并比较表征其结构和热稳定性。在这种情况下，将球磨的竹杆用超声波辐照处理不同的时间（0、5、15和25分钟），在-12°C下用7％氢氧化钠/ 12％尿素溶液溶解，然后用乙醇和二恶烷以获得部分脱木质素的固体馏分。随后，将固体部分用二甲基亚砜萃取，然后在乙醇中沉淀，得到多糖部分。糖分析表明，总糖含量从未经超声辐照制备的多糖级分中的60.63％增加到以25分钟超声辐照时间制备的多糖级分中的81.26％。在所有情况下，葡萄糖都是糖成分的主要成分（约50-55％），木糖（约41-44％）是次要主要成分。光谱（FTIR，〜1H-NMR，〜（13）C-NMR和HSQC）分析表明，多糖级分主要由（1→4）直链淀粉和（1→4）连接的α-D-葡聚糖组成。连接的β-D-木聚糖与少量的半纤维素支链糖连接。另外，热分析表明多糖级分的主要降解阶段发生在210至320℃之间。与没有超声辐射制备的多糖级分相比，通过超声辐射制备的多糖级分具有稍低的热稳定性。

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