Fourier Transform Infrared Spectroscopy For Rapid Detection Of Authenticity And Adulteration Of Edible Oils

Oils provide the necessary nutrition and energy for the body, the quality of them have a great influence on human health. In recent years, more and more safety issues of edible oils have been widely concerned. Fourier transform infrared spectroscopy (FT-IR) combined with chemometric was applied for the authenticity of edible oils, sesame oil and determination of sesame oil adulterated with soybean oil and sunflower oil. This thesis reported the several applications of FT-IR.1. FT-IR combined with Soft Independent Modeling of Class Analogy (SIMCA) was applied for the authenticity of edible oils. The method was based on the fingerprint characteristics of FTIR. FTIR spectra of53qualified oils and13adulterated oils were collected and analyzed. Then, the whole wavelength, second derivative and SNV were chosen as the pretreatment method. Two principal components extracted by PCA as the characteristic variables involved in pattern recognition. Finally, according to the method requirements of SIMCA, the training set and validation set were randomly selected from the FTIR spectra of all samples, the model of SIMCA classification was build. It was proved that recognition rate and rejection rate were100%. In general, FTIR-SIMCA could be used as a new method for rapid identification of edible oils.2.Authentication of sesame oils by GC and FTIR-SIMCA. GC and FTIR-SIMCA were used to analyze70samples of sesame oils. Depending on the differences of fatty acid composition of different edible oils,6kinds of main fatty acids of sesame oils, such as palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid and arachidic acid, were analyzed by GC.70samples were divided into42sesame oil and28adulterated sesame oil.The result of FTIR-SIMCA was consistent with that of GC, it can provide a new method for rapid identification of sesame oil. 3. Sesame oil was often adulterated with low price oils. FTIR spectra of sesame oil, soybean oil adulterated into sesame oil, sunflower oil adulterated into sesame oil were analyzed by PCA. Then, the peaks in1800～650cm-1, the second derivative and SNV were chosen as the pretreatment method. The result showed that the incorporation over10%of soybean oil or sunflower oil in sesame oil can be divided into3categories. Further, FTIR combined with partial least squares (PLS) method was established to determine soybean oil or sunflower oil in sesame oil. The standard error of prediction (SEP) were1.151and1.351,respectively. Meanwhile, the relative error of prediction was between-6.87%～8.07%, the differences were not significant. In a word, FTIR combined with chemometrics can qualitatively and quantitatively analyze the content of sesame oil adulterated with more than10%soybean oil and sunflower oil.In summary, as a traditional means of analysis, FTIR combined with chemometric methods can be used for the detection of authenticity and adulteration of edible oils.