利用傅里叶变换红外光谱对6种菜豆(白芸豆、奶花芸豆、黑芸豆、雀蛋豆、紫花芸豆,红小豆)进行鉴别研究。测试了6种菜豆36个样品的红外光谱,结果表明:6种不同品种菜豆的红外图相似,仅在1 800~800 cm-1范围内红外光谱的峰位、峰形及吸收强度有一些微小差异。对原始光谱作二阶导数光谱处理,在1 800~800 cm-1范围内6种菜豆的二阶导数光谱图差异明显,利用该范围二阶导数光谱数据对6种豆类样品进行主成分分析、聚类分析,前3个主成分分类正确率为97.1%,聚类分析正确率为97.2%。对1 700~1 600 cm-1波段范围的原始光谱进行曲线拟合,结果显示,6种菜豆的蛋白质二级结构中α-螺旋含量、β-转角含量、无规则卷曲结构含量和β-折叠含量不同。结果表明傅里叶变换红外光谱技术结合统计分析的方法可以把不同品种的菜豆区分开来。

Fourier transform infrared (FTIR) spectroscopy was used to study six species of phaseolus vulgaris (white kidney bean, light speckled kidney bean, black kidney bean, Phaseolus coccineus L. var. albonanus Bailey, Purple speckled kidney bean and Vigna umbellate). The results showed that the infrared spectra of phaseolus vulgaris were similar, but tiny differences in wave-numbers and absorption intensities of peaks were observed in the range of 1 800~800 cm-1. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) were performed on the second derivative infrared spectra in this region. The first three principal components have a cumulative contribution rate of 94% and yields classification accuracy of 97.1%, hierarchical cluster analysis provides about 97.2% of correct classification. The amide I band (1 700~1 600 cm-1) in the original spectra was used for curve fitting to evaluate the contents of secondary structure of protein. The results show the contents of α-helix, β-turn, unordered structure and β-sheet were dissimilar in six kinds of phaseolus vulgaris. It is proved that FTIR spectroscopy combined with statistical analysis could be used to discriminate Phaseolus vulgaris.