燕窝与银耳红外光谱、热分析及微观结构对比研究

Comparison on infrared spectrum,thermal properties and microstructure between edible bird’s nest and tremella

为区分燕窝与银耳,利用红外光谱(FTIR)分析了燕窝与银耳化学官能团,并对二者红外光谱一阶导数、Norris一阶导数和二阶导数图进行分析,利用综合热分析仪分析其在受热过程中的热性能,扫描电镜(SEM)观察二者表面微观结构。结果表明,燕窝和银耳红外光谱主要吸收峰形状相似、位置相近,但吸收峰强度有较大差异,燕窝主要吸收峰强度大。二者在3431、2922 cm^-1均有蛋白质、氨基酸及多糖分子羟基、甲基和亚甲基吸收峰,在1636、1448、1384 cm^-1分别有蛋白质酰胺Ⅰ带、酰胺Ⅱ带、酰胺Ⅲ带伸缩振动吸收峰,而银耳在1732 cm^-1有脂肪吸收峰,在波数小于1300 cm^-1指纹区,燕窝和银耳红外光谱一阶导数、Norris一阶导数和二阶导数图差异较大。燕窝与银耳热失重曲线和DSC曲线有明显差异,燕窝在160~400℃热失重较大,而银耳在250~400℃热失重较大,且银耳热失重及吸放热比燕窝大。燕窝和银耳表面微观结构有明显差别,燕窝表面光滑,有明显条形纹理,大纹理沿某方向取向,小纹理纵横交错,银耳表面有大量凸体结构,且凸体相互堆积。

In order to distinguish the chemical structure,thermal properties and microstructure between edible bird’s nest and tremel⁃la,the chemical functional groups of edible bird’s nest and tremella were analyzed with infrared spectrum(FTIR),the first and the second derivatives as well as Norris first derivative of FTIR were studied,the thermal properties were analyzed with comprehensive thermal analyzer,and their surface microstructure were observed with SEM.The results showed that the main absorption position of in⁃frared spectrum of edible bird’s nest was close to tremella while the absorption peak intensity are fairly different with that of edible bird’s nest being stronger.The absorption peaks of protein,amino acid,and the hydroxyl,methyl,and methylene of polysaccharide were observed at 3431 and 2922 cm^-1.The protein amide Ⅰ band,Ⅱ band,and Ⅲ band stretching absorption peak were observed at 1636,1448,1384 cm^-1.However,tremella had absorption peak of fat around 1732 cm^-1.In the fingerprint region with a wave num⁃ber less than 1300 cm^-1,the first and the second derivatives and the Norris first derivative of edible bird’s nest and tremella showed great differences.Thermal weight loss curves and DSC curves betweenedible bird’s nest and tremella were significantly different.Ther⁃mal weight loss of bird’s nest was greater at 160~400℃,while that of tremella was greater at 250~400℃.There are distinct differenc⁃es on microstructure ofedible bird’s nest and tremella.Obvious strip texture oriented in a certain direction can be seen on the surface of edible bird’s nest while considerable convex body accumulated on the surface of tremella.The results provided the basis to distin⁃guish edible bird’s nest and tremella in spectral analysis and microstructure using integrated approaches.