Determination of olive oil free fatty acid by fourier transform infrared spectroscopy

Abstract

A new procedure for determining free fatty acids (FFA) in olive oil based on spectroscopic Fourier transform infrared-attenuated total reflectance spectroscopy measurements is proposed. The range of FFA contents of samples was extended by adding oleic acid to several virgin and pure olive oils, from 0.1 to 2.1%. Calibration models were constructed using partial least-squares regression (PLSR). Two wavenumber ranges (1775-1689 cm −1 and 1480-1050 cm −1 ) and several pretreatments [first and second derivative; standard normal variate (SNV)] were tested. To obtain good results, splitting of the calibration range into two concentration intervals (0.1 to 0.5% and 0.5 to 2.1%) was needed. The use of SNV as a pretreatment allows one to analyze samples of different origins. The best results were those obtained in the 1775-1689 cm −1 range, using 3 PLSR components. In both concentration ranges, at a confidence interval of α = 0.05, no significant differences between the reference values and the calculated values were observed. Reliability of the calibration vs. stressed oil samples was tested, obtaining satisfactory results. The developed method was rapid, with a total analysis time of 5 min; it is environment-friendly, and it is applicable to samples of different categories (extra virgin, virgin, pure, and pomace oil).Paper no. J8932 in JAOCS 76, 611-616 (May 1999). FIG. 3. Absolute errors for calibration (•) and prediction samples (• •) obtained in the absorbance mode and wavenumber range 1775-1689 cm −1 .

Oral Thresholds and Suprathreshold Intensity Ratings for Free Fatty Acids on 3 Tongue Sites in Humans: Implications for Transduction Mechanisms

“…Receptor-mediated transduction may predominate at low stimulus concentrations, but when receptor binding is saturated and FFAs are available, diffusion may be the predominant route of passage across membranes (Ibrahimi and Abumrad 2002). Unbound FFA concentrations in the circulation may be in the nanomolar range (Azzazy et al 2006), but concentrations 6-8 orders of magnitude higher may occur in the oral cavity while eating (Rukunudin et al 1998;Wan et al 1998;Bertran et al 1999;Che Man et al 1999;Gopala Krishna et al 2006;Li et al 2008).…”

Vibrational Spectroscopy of Food and Food Products

“…33 The principles of this PV method were also employed in the development of a PLS-based FT-NIR method. 34 FT-IR methods for the determination of other minor components present in oils, including free fatty acids in refined 35,36 and crude oils, 37,38 b-carotene in palm oil, 39 and phospholipids in vegetable oils, 40 have also been reported.…”

Quantitative determination of free fatty acids in extra virgin olive oils by multivariate methods and Fourier transform infrared spectroscopy considering different absorption modes

“…[17] For the determination of FFAs in EVOOs using spectroscopic methods, a number of articles have been published. Bertran et al [18] developed a new procedure for determining FFAs in olive oil based on spectroscopic FTIR-attenuated total reflectance (ATR) spectroscopy. They used only one absorption mode and used two wavenumber ranges (1775-1689 cm −1 and 1480-1050 cm −1 ) and several pretreatments including first and second derivatives and standard normal variate.…”