使用太赫兹时域光谱技术对生物饲料添加剂中的地衣芽孢杆菌、枯草芽孢杆菌、凝结芽孢杆菌三种益生菌进行了室温、充氮环境下太赫兹时域光谱测试。得到了样品在0.2~1.6 THz波段的太赫兹吸收光谱和折射率谱。实验结果表明, 随着频率增加三种益生菌的THz波段的吸收系数是增加的, 并且有不同的吸收趋势及明显的特征吸收峰, 这意味着三种样品的分子及官能团的构成和存在状态是不同的。三种样品明显不同的平均折射率(分别是1.71, 1.67, 1.64)说明太赫兹光通过样品时所产生的色散和吸收是不同的, 这更有力地揭示三种样品的确具有不同的生物成分组成和结构。为了更好地比较和说明太赫兹波识别鉴定益生菌的优势, 还进行了同条件下的红外测试。通过对比发现菌制剂在太赫兹波段比在中红外波段更具有吸收活性, 更能体现其结构差别, 是红外光谱测试的有效辅助手段, 同时, 文中还依据益生菌的生物结构特征首次给出了机理上的解释和探讨。这项研究表明太赫兹时域光谱技术能够填补益生菌检测手段的匮乏, 为益生菌的检测乃至为其它生物饲料添加剂检测提供了一种行之有效的方法。

Three kinds of probiotics in the biological food additives which are respectively Bacillus licheniformis, Bacillus subtilis and Bacillus coagulans have been tested and investigated with the terahertz time-domain spectroscopic(THz-TDS) technique at room temperature in nitrogen environment in the paper. The absorption coefficient and refraction index of three probiotics samples were calculated in the frequency of 0.2-1.6 THz. Test reveal that the absorption coefficients is increased as frequency increases and has considerable different absorption trend and characteristic absorption peaks among the samples, which means the vibration information made up of different molecular vibration and multi-molecular group is different in the THz spectrum of three samples. Furthermore, the average refractive indices were 1.71, 1.67 and 1.64 corresponding to Bacillus licheniformis, Bacillus subtilis and Bacillus coagulans, respectively. The refractive value indicates that abnormal dispersion, which meant three samples had the characters of strong selective absorption in this wave band. In contrast, the Fourier transform infrared spectroscopy(FTIR) in the 400-4 000 cm-1 was utilized to measure the IR absorption spectra, and the results revealed that the probiotics is more active in the range of Terahertz than in the IR band and terahertz can be a good supplementary means of IR test. Meanwhile, some explanation on mechanism was put forward in this paper. The experiments showed that THz-TDS is a powerful tool to complement the conventional analytical approaches and can be applied to detect and identify the features of the constituent in probiotics or other biological food additives.