Rapid Assessment of Monovarietal Portuguese Extra Virgin Olive Oil's (EVOO's) Fatty Acids by Fourier‐Transform Near‐Infrared Spectroscopy (FT‐NIRS)

Abstract

A rapid method for the evaluation of fatty acids (FA) of monovarietal Portuguese extra virgin olive oils (EVOOs) (n = 82) from Alentejo, south‐central region of Portugal, is developed based on Fourier‐transform near‐infrared spectroscopy (FT‐NIRS). The contents of FA‐components (previously determined per conventional gas chromatography) are correlated with FT‐NIRS data (independent variable), by means of full cross‐validation partial least squares regression (CVPLSR). CVPLSR is run using standard normal variate (SNV) data pre‐processing and the nonlinear iterative partial least squares (NIPALS) algorithm. Obtained correlation models are characterized with good statistics: high correlation coefficients (R > 0.85) and low root mean square errors (RMSE < 2.04). Obtained values of the residual predictive deviation (RPD) of CVPLSR‐model, higher than 5.0 (C18:1, C18:2, MUFA, PUFA) confirm the FT‐NIRS as a potential method for rapid quality control of EVOO's FA. Practical Applications: In this work for the first time, fatty acid (FA) profile of monovarietal extra virgin olive oil (EVOO) samples of the greatest olive region in Portugal—Alentejo—is analyzed by Fourier‐transform near‐infrared spectroscopy (FT‐NIRS) and chemometrics. Obtained high‐quality results allow one to recommend this technique from monitoring to quality control analysis of FA (in particular, of representative unsaturated FA), in a great number of olive oil samples, in near‐real time. Quality of olive oil can be assessed by target or non‐target analysis and it is of mandatory importance. Fourier‐transform near‐infrared spectroscopy (FT‐NIRS), combined with chemometrics, for the analysis of the fatty acid profile of varietal olive oils from Alentejo (Portugal) can be a useful technique for quality control. Furthermore, FT‐NIRS is rapid, non‐destructive, and a more environmental friendly technique.

Evaluation of Near Infrared Spectroscopy (NIRS) and Remote Sensing (RS) for Estimating Pasture Quality in Mediterranean Montado Ecosystem

“…Five spectra were collected from each sample, and an average spectrum was used for further mathematical processing and chemometrics analysis. Spectra data were obtained in the entire near infrared region of 12,500-3600 cm −1 (800-2777 nm) after a total of 32 scans with a scanner velocity of 10 kHz and an average resolution of 16 cm −1 , with a receiver gain function with the lowest gain setting defined as 1 [23]. Each spectrum constituted 1137 points, which means that the first 20 values of each spectrum were discarded because large parts of the spectral noise could be found below 3741 cm −1 (2673 nm).…”

Seeking a Fast Screening Method of the Varietal Origin of Olive Oil: The Usefulness of an NMR-Based Approach

“…It is also interesting to notice that Gal olive oils are the ones with the best performance in the model based on 13 C NMR DEPT 45. Galega Vulgar olive oils have already proven to be different from other varieties, namely, through their volatile profile [ 3 ] and their fatty acid profile [ 6 ]. The authors show that by applying a linear discriminant analysis to the fatty acids of olive oils from Alentejo, Galega Vulgar olive oils are very well separated from other olive oil varieties.…”

“…Few studies related to olive oils produced in Portugal using the typical olive varieties are described in the literature, mainly based on the use of chromatographic and spectroscopic techniques and chemometric tools [ 1 , 2 , 3 , 4 , 5 , 6 ]. Peres and coworkers [ 1 ] used artificial neural networks to achieve a chemometric classification of olive cultivars from Cobrançosa, Cordovil, Madural, Negrinha de Freixo, Santulhana and Verdeal Transmontana from the Trás-os-Montes region (northeast of Portugal).…”

“…Other research work has applied short-wavelength Raman spectroscopy and Fourier transform infrared spectroscopy (FTIR) for the discrimination and classification of Cobrançosa, Galega Vulgar and Picual olive oils [ 4 , 5 ]. More recently, 82 monovarietal extra virgin olive oil (EVOO) samples from nine different cultivars in the Alentejo region were used to assess the fatty acid component by Fourier-transform near-infrared spectroscopy (FT-NIRS) [ 6 ].…”

Evaluation of Near Infrared Spectroscopy (NIRS) for Estimating Soil Organic Matter and Phosphorus in Mediterranean Montado Ecosystem

“…An average spectrum was collected from each sample and was used for further mathematical processing and chemometrics analysis. Spectra data were obtained in the entire near infrared region of 12,500-3600 cm −1 (800-2777 nm) after a total of 32 scans with a scanner velocity of 10 kHz and an average resolution of 16 cm −1 , with a receiver gain function with the lowest gain setting defined as 1 [15]. The first 70 values of each spectrum were discarded to eliminate the noise below 4065 cm −1 (2460 nm).…”