Rapid synchronous fluorescence method for virgin olive oil adulteration assessment

This paper describes the differentiation of virgin olive from olive-pomace, corn, sunflower, soybean, rapeseed and walnut oils using total synchronous fluorescence (TSyF) spectra. TSyF spectra are acquired by varying the excitation wavelength in the region 250-720 nm and the wavelength interval (A) in the region from 20 to 120 nm. It is shown that adulterants can be discriminated from virgin olive oil using a wavelength interval of 20 nm and excitation wavelength region 315-400, 315-392, 315-375, 315-365, 315-375 and 315-360 for olive-pomace, corn, sunflower, soybean, rapeseed and walnut oils, respectively. Thirty one virgin olive oil mixtures with each potential adulterant were prepared at varying levels with emphasis at low concentrations. The partial least-squares regression model was used to quantify adulteration. This technique is useful for detection of olive-pomace, corn, sunflower, soybean, rapeseed and walnut oil in virgin olive oil at levels of 2.6%, 3.8%, 4.3%, 4.2%, 3.6%, and 13.8% (w/w), respectively. (C) 2007 Elsevier Ltd. All rights reserved.