【作者】 赵毅；

【导师】 庞树峰；

【作者基本信息】 北京理工大学 ， 化学， 2015， 硕士

【摘要】 本文主要是利用傅里叶变换显微红外光谱仪，以多孔菌类植物黑木耳和茯苓为研究对象，研究在加湿过程中其组分的结构变化。黑木耳是一种珍贵资源，它既有食用价值，还有药用价值。众所周知，浸泡黑木耳是我食用之前必须采取的措施。那么水浸泡以后，黑木耳的结构到底会发生怎么样的变化呢？在此，我们利用傅里叶变换显微红外光谱仪来探究黑木耳在吸湿过程中分子结构的变化。在常温常压下，我们通过改变样品室的相对湿度来控制黑木耳的吸水量。分析黑木耳中多糖分子红外特征吸收峰的变化，推断在吸水的过程中黑木耳的内部结构的变化。为了更好的了解水与黑木耳多糖分子的作用机理，本文对3000~3800cm-1的光谱进行拟合，发现水与多糖分子主要是以强氢键的形式存在。当相对湿度小于22%时，羧基中的C=O基团吸收峰发生红移，峰位由1735变化到1730cm-1，说明在第一阶段主要是羧基中的C=O基团与水分子发生作用。当相对湿度大于22%且小于37%时，羧基中的C-O基团吸收峰发生蓝移，峰位由1245变化到1250cm-1，说明在第二阶段主要是羧基中的C-O基团与水分子发生作用。随着相对湿度继续增强，羧基的C=O和C-O基团吸水达到饱和，水分子开始与自身发生作用形成水簇，并且还加快了与多糖分子中的亲水基团之间作用。茯苓是一种附着在松树根上生长的真菌，作为我国传统中药，具有安神、健脾、利尿等功效，近年来又发现茯苓多糖及其衍生物有抗肿瘤活性。茯苓属于一种多孔菌科，主要成分是三萜类化合物和多糖类化合物，其中的多糖类化合物主要是以直链β-(1→3)-D-葡聚糖的形式存在。因为茯苓内部物质属于高度的混合物，所以单纯依靠光谱的原谱是不能够很好地分析结构的变化，我们还采用了差谱和光谱拟合的手段，充分理解茯苓吸水过程中结构的变化。首先通过观察光谱原谱，我们发现1417cm-1处的峰位发生位移，此峰归属于茯苓三萜类化合物中的=CH2基团，说明在加湿过程中水分子与三萜类化合物发生作用。同时对3000~3800cm-1的光谱进行拟合，我们得出=CH2基团在低湿度下主要形成的是强氢键，在高湿度下形成的是弱氢键。根据差谱我们还可以推断出随着相对湿度的增加，茯苓糖环分子中的C1-OH、C2-OH、C3-OH分别与水分子形成C1-OH···H2O、C2-OH···H2O、C3-OH···H2O三种稳定构型。更多还原

【Abstract】 Auricularia and poria cocos are both valued as edible and medicinal resources.Their hydration is a fundamental process when eaten. In order to know the effect ofwater on the structure of auricularia and poria cocos, the Micro-Fourier transforminfrared spectroscopy (Micro-FTIR) technique has been used and the gained IRspectra are measured and analyzed in detail.The IR peak of water as well as that of auricularia was found to be sensitive tohydration. By the band fitting at3258cm-1at low relative humidity (RH), it wasfound that strong hydrogen bonds were formed between water molecules andpolysaccharide. In detail, strong hydrogen bonding was formed between the watermolecules and the carboxyl C=O groups of polysaccharide at first at RH22%, whichwere reflected by a red shift of the C=O stretching band from1735to1730cm-1. Withincreasing RH from22to37%, the strong hydrogen bonding was formed betweenwater molecules and carboxyl C-O groups, exhibiting a blue shift from1245to1250cm-1for the C-O(H) stretching band. With further increase of RH, the watermolecules continuously bonded with OH groups of polysaccharide and evenaggregated to form clusters with spectral characteristic of bulk water.In Poria cocos, Triterpene compound and polysaccharides are main compositionin poria cocos. The heteropolysaccharide was identified as a linear chain of β-(1→3)-D-glucan. Because of strong overlaps between some bands, the difference spectraand band decompositions has been applied to analysis the structural change. IRspectra show the transform of hydrogen bonds with the RH. It means that the=CH2groups (1417cm-1) form strong hydrogen bond with water molecules at lower RH,and then some transfer to weak hydrogen bond with the increase in RH. The furtherstudy suggests that the C1-OH、C2-OH、C3-OH groups from polysaccharide bond toform C1-OH···H2O、C2-OH···H2O、C3-OH···H2O steady modes, respectively, withwater molecules.更多还原