Discrimination of Edible Vegetable Oil Adulteration with Used Frying Oil by Low Field Nuclear Magnetic Resonance.

Pleasant flavor and nutritional benefits of vegetable oils lead to an increase in their consumption amount. In addition, due to being apparently similar to commercially qualified vegetable oils (QVOs), used frying oil (UFO) is added into it to seek high profit by the unscrupulous traders. Thus, the authenticity assurance of commercial oil and fat products remains a challenge to scientists both in terms of its health and commercial perspectives. This work focused on using low field nuclear magnetic resonance (LF-NMR) to discriminate the adulteration of commercial corn, peanut, rapeseed, and soybean oils with two kinds of UFOs. The differences between the transverse relaxation distributions ( T distributions) of qualified oil and UFO were in the appearance of the third peak (A), which could be assigned to polymer products that were produced during the deep-fat frying process and the shift of T value of the peaks. In addition, the A peak area accounted for the whole area of peaks linearly increasing along with the increase in adulteration proportion. Based on the changes of peak area, a simple linear equation was built and the determination coefficients ( R) were all higher than 0.93. Therefore, as a rapid, convenient, and nondestructive method, LF-NMR application could be used to detect adulteration of vegetable oils with UFO. [ABSTRACT FROM AUTHOR]