Fast quantitative determination of iodine value in vagetable oil by using laser Raman spectroscopy and PLS

To establish a nondestructive and rapid analysis method of determining iodine value in vegetable oil with no reagent using laser Raman spectroscopy combined with partial least square(PLS),taking soybean oil,olive oil,peanut oil,sesame oil and their blend oil as samples,their Raman spectra are collected, with the range of 250—2400 cm~(-1),and their signals are assigned.A variety of experimental conditions affecting Raman spectroscopy determination are investigated.Take the iodine value determined by traditional Wechsler as contrast,with combination of chemometric methods to establish a Raman spectroscopy quantitative model of iodine value.The experimental results show that the Raman spectroscopy peak shapes and displacements of soybean oil,olive oil,peanut oil and cooking oil have a certain similarity, while the Raman spectroscopy of sesame oil has a strong fluorescence interference,and there is obvious difference of the peak intensity with the other vegetable oil samples.The iodine value correction model is established with the coefficient of determination R~2=97.49,and the cross-validation calibration standard deviation(RMSECV) of 1.15.The test set standard error of prediction(RMSEP) is 1.57,and the coefficient of determination R~2 is 96.47.The results show that the application of Raman spectroscopy combined with chemometrics in the rapid detection of iodine value in vegetable oil is feasible.