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Determination of olive oil free fatty acid by fourier transform infrared spectroscopy
Author(s) -
Bertran Enriqueta,
Blanco Marcelo,
Coello Jordi,
Iturriaga Hortensia,
Maspoch Santiago,
Montoliu Ivan
Publication year - 1999
Publication title -
journal of the american oil chemists' society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.512
H-Index - 117
eISSN - 1558-9331
pISSN - 0003-021X
DOI - 10.1007/s11746-999-0011-9
Subject(s) - partial least squares regression , calibration , chemistry , fourier transform infrared spectroscopy , analytical chemistry (journal) , fatty acid , pomace , oleic acid , attenuated total reflection , mathematics , second derivative , infrared spectroscopy , chromatography , infrared , food science , statistics , optics , organic chemistry , biochemistry , mathematical analysis , physics
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).