TFA Adulteration Detection Of Sesame Oil

The adulterated sesame oil is commonly found in the present. For the purpose ofqualitative and quantitative detection of sesame oil, laboratory-made hydraulic sesame oil wasselected as the main raw material, second-grade cottonseed oil, and third-grade cottonseed oil,first-grade rapeseed oil, and crude rapeseed oil were used as adulterated oil sample. In thetrifluoroacetic acid (TFA) color reaction, the five vegetable oils showed vary greatly color andUV-visible spectral scanning curve, which can initially achieve the identification among thepure oil samples. According to the TFA color reaction, the color reaction difference andUV-visible spectral scanning curves of sesame oil mixed with different ratios of cottonseed oilof were analyzed and summarized.In the study, petroleum ether was screened as the solvent of TFA color study. Then theeffect of the amount of oil sample, petroleum ether and TFA on color reaction was discussed.Under optimum color reaction conditions1mL oil sample,4mL petroleum ether,1mL TFA thecolor among different oil samples were also darker and easy to distinguish. The TFA colorreaction and UV-visible spectral scanning curve in the wavelength of350nm-370nm of thefive vegetable oil laboratory-made hydraulic sesame oil, second-grade cottonseed oil,third-grade cottonseed oil, first-grade rapeseed oil and crude rapeseed oil were investigated.The results showed that colors change of five vegetable oils was remarkable before and afterreaction are obviously separated by TFA color reagent, which as shown by comparing thecolors of color measurement instrument are: yellow-green, yellow-orange, dark red-orange,red-purple, dark red-orange respectively. And colors change of five vegetable oils wasremarkable before and after reaction. Further, the UV-visible spectral scanning curve wasdramatically changed; correspondingly five characteristic absorption wavelengths ofvegetable oil had greatly changed.On the basis of different pure vegetable oils in a variety of color reaction of TFA, thequalitative and quantitative detection of adulteration sesame oil mixed with cottonseed oil wasstudied. The effect of amount of oil sample, petroleum ether, and TFA on the colors ofdifferent proportion adulterated oil samples was examined, and reaction condition wasdetermined as follows: different proportions oil samples0.5mL, petroleum ether2mL, TFA0.5mL were mixed until about45min followed by2mL of petroleum ether added, and the significant color difference among samples was obtained. The color reaction method is thevisual detection method. Under the same conditions, after occurred color reaction, theadulteration sesame oil mixed with different proportions cottonseed oil were immediatelyscanned with the UV-visible spectrophotometer at350nm-700nm wavelength scanning, thetendency of the scan curves were analyzed and summarized. Verification of the oil samplesshowed that TFA visual detection method and UV-visible scanning method are more effectivein detecting adulterated oil sample.