Analysis Of Spirulina Quality And Radiation Characteirstic Using FTIR Spectroscopy

Spirulina is one of the oldest single cell green lives in the word. The main components of Spirulinaare protein, saccharides, a little lipids and abundant micronutrient such as vitamin and mineral substance.Spirulina has the effect on decreasing the blood pressure, antioxidant, improving immunity andanticancer. Because of these nutritional and functional values, Spirulina can bringgreat economicbenefit. The quality of Spirulina products is the top concern of consumers. Thus, the development offast and effective detection method of Spirulina products is the active demand of market managing. Onthe other hand, safe irradiation in sterilization also influences Spirulina’s quality and international trade.Fourier Transfer Infrared Spectrum has the advantages of macroscopic, fast, simple and no damage inanalysis of mixture and it is suitable in quality and irradiation detection of Spirulina.Spirulina has two protein characteristic peaks at1657and1537cm^-1and two saccharidescharacteristic peaks at1154and1069cm^-1in original IR spectra. Through comparion of peak intensities,it is estimated that protein is the most abundant substance and saccharides is the second in Spirulina.The IR spectra of Spirulina powder has similar peaks with a wider amide absorption peaks. The proteinpeaks locate at1658and1542/1537cm^-1and saccharides peaks locate at1054,1080and1016/1024cm^-1with a stair-step shape in IR spectra of Spirulina powder. The IR absorption of dextrin changes thepeak shape and position in Spirulina powder. The peak intensity ratio of amide I to II is1.43inSpirulina while the ratio fall to1.39-1.21in other Spirulina products and the peaks were widened. Thecontent of α-helix in Spirulina protein is24.6%while the content decrease to15.0%in Spirulinapowder and Spirulina tablets. The amide band in2D-IR spectra of Spirulina is smooth and separateabsolutely while amide bands of Spirulina powder and Spirulina tablets are broad, bifurcate andhardlyseparate. The amide I divides into two peaks at1558and1574cm^-1and the amide II divides into1623,1635,1645and1652cm^-1in2D-IR spectra of Spirulina powder. The amide I divides into two peaks at1537,1550and1560cm^-1and the amide II divides into four peaks at1624,1632,1640and1680cm^-1in2D-IR spectroscopy of Spirulina tablet. Spirulina has five auto-peaks at1161,1138,1083,1054, and1026cm^-1in2D-IR spectra. Saccharides characteristic peaks in Spirulina powder and Spirulina tabletsare different from Spirulina in shape and position and they have fewer atuopeaks in2D-IR spectroscopy.Spirulina power has one autopeak at1194cm^-1and Spirulina tablet has two autopeaks at1143and1190cm^-1Through the study of two second derivate and2D-IR spectra, it is found that the interaction betweenprotein molecularsis damaged by irradiation and the secondary structures of protein is changed. Twodimension analysis under thermal-perturbations showes that irradiated samples have different thermaldenaturation processes. The intensity of saccharides autopeak at1012cm^-1increases while the othersaccharides peaks decrease. The higher the intensity, the stronger the thermo sensitivity is. Three stepIR spectra analysis can detect whether the Spirulina powder is irradiated or not. An irradiation dose detection model is established by chemometrics. The identification rate of SIMCA model is100%andrejection rate is higher than95%. The forecast accuracy is96.5%.Spirulina is analyzed using three step IR spectra for the first time and we established the fastspectrum detection method of Spirulina product quality. Based on the changes of IR absorptivecharacter, the irradiation dose prediction model was built.