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Influence of triacylglycerol characterics on the determination of free fatty acids in vegetable oils by fourier transform infrared spectroscopy
Author(s) -
Verleyen T.,
Verhe R.,
Cano A.,
Huyghebaert A.,
De Greyt W.
Publication year - 2001
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/s11746-001-0375-z
Subject(s) - fourier transform infrared spectroscopy , saponification , chemistry , palm kernel oil , repeatability , sunflower oil , vegetable oil , coconut oil , lauric acid , calibration , fatty acid , chromatography , correlation coefficient , soybean oil , analytical chemistry (journal) , food science , palm oil , mathematics , organic chemistry , chemical engineering , statistics , engineering
A rapid and direct Fourier transform infrared (FTIR) spectroscopic method using a 25‐μm NaCl transmission cell was developed for the determination of free fatty acids (FFA) in six important vegetable oils (corn, soybean, sunflower, palm, palm kernel, and coconut oils) that differ in fatty acid profile. The calibrations were established by adding either standard FFA (oleic, lauric acids) or a representative mixture of FFA obtained after saponification of the refined oils. For all oils, up to a FFA level of 6.5% for coconut oil, the best correlation coefficient was obtained by linear regression of the free carboxyl absorption at 1711 cm −1 . All correlation coefficients were greater than 0.993, and no significant difference between the calibration methods could be detected. Upon validation of the calibration, no significant difference (α=0.05) between the “actual” and the “FTIR predicted” FFA values could be observed. The calibration models developed for the six oils differed significantly and indicate the need to develop a calibration that is specific for each oil. In terms of repeatability and accuracy, the FTIR method developed was excellent. Because of its simplicity, quick analysis time of less than 2 min, and minimal use of solvents and labor, the introduction of FTIR spectroscopy into laboratory routine for FFA determination should be considered.