Determination of fatty acids in the subcutaneous fat of Iberian breed swine by near infrared spectroscopy (NIRS) with a fibre-optic probe.

A near infrared spectrometer equipped with a standard 1210/210 bundle remote reflectance fibre-optic probe, with a 5×5 cm quartz window, was used for the determination of fatty acids in the subcutaneous fat of Iberian pigs. A comparative study was made of the determination of fatty acids (C14:0, C16:0, C18:0, C18:1, C18:2, C18:3, C20: 1, Σpolyunsaturated, Σmonounsaturated and Σsaturated) in samples of subcutaneous fat from Iberian pigs by direct application of the fibre-optic probe on samples of whole subcutaneous fat and with cam-lock cups, assessing extracts of total lipids with diethyl ether. The regression method employed was modified partial least squares (MPLS). Calibration of 157 samples, using the fibre optic probe, allowed determination of fatty acids in the following ranges: C14:0 (0.78-1.77), C16:0 (15.87-29.74), C18:0 (4.61-15.90), C18:1 (43.50-61.27), C18:2 (2.03-13.94), C18:3 (0.13-1.14), C20:1 (0.45-2.32), Σpolyunsaturated (2.31-14.82), Σmonounsaturated (47.37-65.62), Σsaturated (22.09-47.31), with corrected standard errors of prediction SEP(C) of 0.093, 0.56, 0.67, 0.94, 0.42, 0.10, 0.20, 0.46, 0.94, 0.83, respectively. The robustness of the method using the fibre-optic probe was tested in a slaughterhouse using 23 samples for external validation, giving multiple correlation coefficients (RSQ) for C14:0, C16:0, C18:0, C18:1, C18:2, C18:3 C20:1, Σpolyunsaturated, Σmonounsaturated, Σsaturated acids of 0.72, 0.94, 0.72, 0.79, 0.88, 0.55, 0.17, 0.88, 0.74, and 0.90, respectively, and a corrected standard error of prediction [SEP(C)] for these acids (%) of 0.11, 0.60, 0.84, 1.20, 0.77, 0.11, 0.30, 0.76, 1.21, and 1.18, respectively.