Liu H.J.,Chinese Academy of Agricultural Sciences |
Liu H.J.,Key Laboratory of Agro product Processing |
Xu C.H.,Tsinghua University |
Zhou Q.,Tsinghua University |
And 7 more authors.
Radiation Physics and Chemistry | Year: 2013
A three-step infrared (IR) macro-fingerprint method combining conventional IR spectra, and the secondary derivative spectra with two-dimensional infrared correlation spectroscopy (2D-IR), was developed to analyze Spirulina powder before and after gamma irradiation. In the IR spectra, most of the absorption peaks of samples irradiated at 1, 2.7, 6, and 10.4kGy had lower intensities than the non-irradiated ones, whereas peaks at 1152, 1078, and 1051cm-1 were slightly enhanced with irradiation at 2.7, 6, and 10.4kGy. Their second derivative spectra amplified the differences and revealed that irradiation affected the C=O band of carboxylic acid and esters, and the N-H band of proteins. The peaks at 1746 and 1741cm-1, and those at 1730 and 1725 cm-1 became two broad peaks. Meanwhile, the three sharp peaks at 1548cm-1, 1544cm-1 and 1536cm-1 changed to two broad peaks at around 1547 and 1534cm-1 after irradiation at doses higher than 1kGy. The characteristic IR bands from 1700cm-1 to 1600cm-1, which represent the C=O band in proteins, also have different shapes and intensities after irradiation. The finding indicated that irradiation affected the secondary structures of protein which was confirmed by curve fitting results. During the process of increasing the temperature from 50 to 210°C, the ratio of amide I to II in absorption intensities in the 2D-IR spectra of the irradiated samples varied with different response for different samples. Saccharides in Spirulina powder had a higher thermostability than proteins, but the autopeaks of irradiated samples did show differences from the non-irradiated sample. The intensity of autopeaks at 1012cm-1 increased dramatically in the irradiated samples while that of peaks at 1053, 1071, and 1083cm-1 decreased after irradiation. Based on the three-step IR macro-fingerprint method, irradiated Spirulina powder samples were successfully and fast identified and discriminated. © 2012 Elsevier Ltd.
Liu H.-J.,Chinese Academy of Agricultural Sciences |
Liu H.-J.,Key Laboratory of Agro Product Processing |
Xu C.-H.,Tsinghua University |
Li W.-M.,Chinese Academy of Agricultural Sciences |
And 12 more authors.
Guang Pu Xue Yu Guang Pu Fen Xi/Spectroscopy and Spectral Analysis | Year: 2013
Spirulina, Spirulina powder and dextrin standard were analyzed and identified by Infrared (IR) spectroscopy. The main components, protein(1657 and 1537 cm-1) and carbohydrate(1069 and 1054 cm-1), had distinct fingerprint characteristics of IR spectra. By comparing the IR spectra of Spirulina, Spirulina powder and dextrin standard, the dominant nutrition in Spirulina powder was identified as protein and carbohydrate. The dominant accessory added in Spirulina powder was dextrin. Comparing the IR spectra of Spirulina powder from 28 different factories and figuring out the correlation provides the information about the amount of accessory. A standard curve of the ratio of absorption peak intensities to protein content was constructed to accurately determine the amount of protein in Spirulina powder.