On-line non-destructive determination of proteins and infiltrated fat in Iberian pork loin by near infrared spectrometry with a remote reflectance fibre optic probe Original Research Article

A near infrared (NIR) spectrometer equipped with a standard 210/210 bundle remote reflectance fibre optic probe, with a 5 cm×5 cm quartz window, was used for the determination of protein and infiltrated fat in the pork loin muscle of Iberian swine (Longissimus dorsi). The content in infiltrated fat was found to vary from 3 to 19% and that of protein from 21 to 31%. The regression method employed was modified partial least squares (MPLSs). The calibration results using the fibre optic probe for 56 samples had corrected standard error of prediction of 0.74% for the fat (multiple correlation coefficient, RSQ=0.94) and of 0.80% for the protein (RSQ=0.881). A comparative study was carried out on the determination of fat and protein in the same pork loin samples using the fibre optic probe without destruction of the sample and with conventional measuring cells using ground samples. The method was applied in the dissecting hall of a slaughterhouse. The results show that NIR interaction, with direct application of a fibre optic probe on pork loin samples, permits the determination of protein and infiltrated fat without destruction the sample, with good results.