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The potential of fluorescence spectroscopy for detecting adulteration of extra virgin olive oil with olive oil was investigated. Synchronous fluorescence spectra were collected in the region of 240-700 nm with wavelength intervals (Dl) of 10, 30, 60 and 80 nm. Regression models were used to quantify the detection limits of adulteration. The technique applied proved to be useful for detecting the addition of olive oil to extra virgin olive oil. The lowest detection limits of adulteration (8.9% and 8.4%) were observed when the wavelength interval applied were 60 and 80 nm, respectively.

The fraudulent addition of plant oils during the manufacturing of hard cheeses is a real issue for the dairy industry. Considering the importance of monitoring adulterations of genuine cheeses, the potential of fluorescence spectroscopy for the detection of cheese adulteration with plant oils was investigated. Synchronous fluorescence spectra were collected within the range of 240 to 700 nm with different wavelength intervals. The lowest detection limits of adulteration, 3.0 and 4.4%, respectively, were observed for the application of wavelength intervals of 60 and 80 nm. Multiple linear regression models were used to calculate the level of adulteration, with the lowest root mean square error of prediction and root mean square error of cross validation equalling 1.5 and 1.8%, respectively, for the measurement acquired at the wavelength interval of 60 nm. Lower classification errors were obtained for the successive projections algorithm-linear discriminant analysis (SPA–LDA) rather than for the principal component analysis (PCA)–LDA method. The lowest classification error rates equalled 3.8% (∆λ = 10 and 30 nm) and 0.0% (∆λ = 60 nm) for the PCA–LDA and SPA–LDA classification methods, respectively. The applied technique is useful for detecting the addition of plant fat to hard cheese.

RESUMEN Discriminación de aceites de oliva comestibles mediante espectroscopía de fluorescencia sincrónica y análisis multivarianteSe ha investigado el potencial de la espectroscopía de fluorescencia para la clasificación de los aceite de oliva. Para ello, se recogieron espectros de fluorescencia sincrónica en el rango de 240-700 nm con intervalos de longitud de onda de 10, 30, 60 y 80 nm. Las proyecciones algorítmicas sucesivas (SPA) se aplicaron para la determinación de las longitudes de onda representativas mientras que el método de análisis discriminante lineal (LDA) se empleó para clasificar los aceites de oliva. Se obtuvo un error de clasificación del método bajo (0,9-6,4%) para las medidas recogidas en todos los intervalos de onda. La mejor precisión de clasificación se obtuvo para intensidades de fluorescencia sincrónica adquiridos a 10 longitudes de onda seleccionadas con intervalos de longitud de onda de 10 nm. PALABRAS CLAVE: Aceite de oliva refinado -Aceite de oliva virgen extra -Aceite de orujo -Espectroscopía de fluorescencia sincrónica -Proyecciones algorítmicas sucesivas. SUMMARY Discrimination of edible olive oils by means of synchronous fluorescence spectroscopy with multivariate data analysisThe potential of fluorescence spectroscopy for the classification of olive oils was investigated. Synchronous fluorescence spectra were collected in the region of 240-700 nm with the wavelength intervals of 10, 30, 60 and 80 nm. Successive projection algorithm (SPA) was applied for the determination of representative wavelengths while the linear discriminant analysis (LDA) method was used to classify olive oils. The classification error of the method was low (0,9-6,4%) for measurements collected at all wavelength intervals. The best classification accuracy was obtained for synchronous fluorescence intensities acquired at 10 selected wavelengths with the wavelength interval equal to 10 nm. KEY-WORDS: Extra virgin olive oil -Pomace olive oil -Refined olive oil -Successive projections algorithmSynchronous fluorescence spectroscopy.