Adulteration Detection Of Eucommia Ulmodies Seed Oil Based On Synchronous Fluoresence And FTIR Spectroscopy

High amounts of polyunsaturated fatty acids and bioactive components in Eucommia ulmoides seed oil,which has higher nutritional value than many common vegetable oils,are observed.Because of its high cost and prices and the enlargement of Eucommia ulmoides seed oil processing industry year by year,the strong market encourages the ambition of illegal merchants to seek windfall profits.In recent years,illegal vendors tend to add cheaper oils into Eucommia ulmoides seed oil among production,storage and sale.In order to monitor the quality of Eucommia ulmoides seed oil and ensure the vital interests of legitimate producers and consumers,it is increasingly important to establish a rapid,simple and environmentally friendly method for quality identification of this oil.Fourier transform infrared（FTIR）spectroscopy and synchronous fluorescence spectroscopy combined with a variety of chemometric tools have been widely used in the qualitative and quantitative identification analysis for quality of food.This study focused on Eucommia ulmoides seed oil and oil samples adulterated with several cheaper vegetable oils.Combination and comparation of FTIR based on polyethylene（PE）film and synchronous fluorescence spectroscopy techniques associated with chemometric tools,such as partial least square regression,principle component analysis,cluster analysis and linear discriminated analysis,as well as qualitative and quantitative analysis were developed to authenticate and predict Eucommia ulmoides seed oil adulteration rapidly.（1）In order to establish discriminant models for adulteration of Eucommia ulmoides seed oil based on synchronous fluorescence spectroscopy,the synchronous fluorescence spectra of Eucommia ulmoides seed oil and Eucommia ulmoides seed oil adulterated with different concentrations of refine rapeseed oil,crude rapeseed oil,peanut oil,corn oil,cottonseed oil and sunflower seed oil were collected.The difference between the excitation and emission wavelengthsΔλwas set at 60 nm,and the widths of excitation and emission were 10 nm.The intensities of synchronous fluorescence spectra were recorded from 250–700 nm.The results showed that significant differences in fluorescence characteristics between Eucommia ulmoides seed oil and other six vegetable oils were observed.The all fluorescence spectra were analyzed by principle component analysis plot based on different wavelength ranges（600-700 nm and 300-500 nm）,respectively.The qualitative identification models were established,with the detection limit of 100%.Therefore, synchronous fluorescence spectroscopy can be employed in characterization and differentiation for adulteration of Eucommia ulmoides seed oil.（2）In order to establish the method for rapidly quantitative determined adulteration of Eucommia ulmoides seed oil,calibrations were established and validated by synchronous fluorescence peaks in the wavelength ranges of 600-700 nm and 300-500 nm and adulteration ratio based on the synchronous fluorescence spectral characteristics of all oil samples.The results showed that the determinant coefficients of the calibrated models were0.9900 and 0.9914,respectively.The determinant coefficients of the validation model were0.9828 and 0.9836,and the detection limit were 1%and 0.48%,respectively.Hence,synchronous fluorescence spectroscopy can be used to detect adulteration of Eucommia ulmoides seed oil.（3）In order to establish discriminant models for adulteration of Eucommia ulmoides seed oil based on FTIR technology,the FTIR spectra of Eucommia ulmoides seed oil and Eucommia ulmoides seed oil adulterated with different concentrations of refine rapeseed oil,crude rapeseed oil,peanut oil,corn oil,cottonseed oil and sunflower seed oil were collected.The infrared absorption intensities of FTIR spectra were recorded from 6000-400 cm^-1.The spectral characteristic peaks for authentication can be analyzed by classification calibration based on spectral differences.partial least square regression,principle component analysis,cluster analysis and linear discriminated analysis were used to qualitatively calibrate adulteration of Eucommia ulmoides seed oil by characteristic spectral regions of FTIR spectra.The results showed that there were significant differences in FTIR spectra between Eucommia ulmoides seed oil and six vegetable oils.FTIR spectra were analyzed by principle component analysis,cluster analysis and linear discriminated analysis plot based on different wavelength ranges(1429-1377 cm^-1 and 1128-1110 cm^-1),respectively.The qualitative identification models based on principle component analysis and cluster analysis were established,with the detection limits of 100%.The detection limits were 100%and 96%based on linear discriminated analysis plot.Therefore,FTIR technique can be employed in characterization and differentiation for adulteration of Eucommia ulmoides seed oil.（4）In order to establish the method for rapidly quantitative determined adulteration of Eucommia ulmoides seed oil,partial least square regression calibrations were developed in effective characteristic bands of FTIR spectra in the wavelength ranges of 1429-1377 cm^-1and 1128-1110 cm^-1.After the optimization process,the optimized calibrations were established to quantitatively determine the adulteration of Eucommia ulmoides seed oil and validated by standard method.The results showed that the FTIR spectra of Eucommia ulmoides seed oil and six other vegetable oils could be calibrated in the wavelength ranges of1429-1377 cm^-1 and 1128-1110 cm^-1.The determinant coefficients of the calibrated models were 0.9875 and 0.9863,and the RMSECV were 2.2041 and 2.2313,respectively.The determinant coefficients of the validation model were 0.9763 and 0.9773,and the detection limits were 1%and 0.48%,respectively.Hence,FTIR combined with partial least square regression could be used to detect adulteration of Eucommia ulmoides seed oil.