Abstract
As it is high in value, extra virgin olive oil (EVOO) is frequently blended with inferior vegetable oils. This study presents an optical method for determining the adulteration level of EVOO with soybean oil as well as peanut oil using LED-induced fluorescence spectroscopy. Eight LEDs with central wavelengths from ultra-violet (UV) to blue are tested to induce the fluorescence spectra of EVOO, peanut oil, and soybean oil, and the UV LED of 372 nm is selected for further detection. Samples are prepared by mixing olive oil with different volume fractions of peanut or soybean oil, and their fluorescence spectra are collected. Different pre-processing and regression methods are utilized to build the prediction model, and good linearity is obtained between the predicted and actual adulteration concentration. This result, accompanied by the non-destruction and no pre-treatment characteristics, proves that it is feasible to use LED-induced fluorescence spectroscopy as a way to investigate the EVOO adulteration level, and paves the way for building a hand-hold device that can be applied to real market conditions in the future.
Highlights
Known as the “Queen of Vegetable Oil” or “Liquid Gold”, olive oil has been involved in the diet of human beings for more than 4000 years
Our method proves that it is possible to detect the adulteration level using light-emitting diodes (LEDs)-induced spectroscopy, and the results pave the way for building a hand-held device that can be used in real market conditions in the future
An optical method based on LED-induced fluorescence technology and spectral analysis technology to identify the doping ratio of extra virgin olive oil (EVOO) over edible vegetable oil is proposed
Summary
Known as the “Queen of Vegetable Oil” or “Liquid Gold”, olive oil has been involved in the diet of human beings for more than 4000 years. It is feasible to classify edible vegetable oils with the help of an electronic nose [6], high-performance liquid chromatography (HPLC) [7,8], mass spectrometry [9], nuclear and magnetic resonance spectrometry (NMR) [10,11], etc These methods have disadvantages, such as high equipment cost, long consuming time, tedious measurement process, and samples destruction, etc., which limit their application to blended oil detection in real life. Laser-induced fluorescence (LIF) spectroscopy employs laser with certain wavelength and strength to induce specific fluorescence signals, which act as “fingerprints” for classification This technology has been applied to fields, such as EVOO adulteration [17,18,19] and tea classification [20], etc. Compared with LIF, LED-induced fluorescence spectroscopy requires less maintenance skills, smaller installation volume, and much lower cost, especially in the UV region
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