Use of NIRs for the assessment of meat quality traits in Iberian montanera pigs

Iberian pig rearing system is characterized by a montanera final period based on acorns and grass as feed. This traditional system combined to the genetic characteristics of the breed can influence meat quality. Determination of meat characteristics by a rapid and no destructive technique as Near Infrared Spectroscopy can be useful in order to highlight the qualitative proprieties of fresh meat. The object of this study was to investigate the FT-NIRs capacity to estimate qualitative characteristic of Iberian pigs intact fresh meat. Purebred Iberian castrated male pigs (n=287) slaughtered at 17 months of age and at an average weight of 165 kg, were used in the present study. From each carcass, samples of Longissimus dorsi muscle were removed, vacuum-packed and stored at -20ºC until analysis. Traditional analysis was applied in order to determine tenderness (with Warner-Bratzler Shear Force and Texture Profile Analysis), myoglobin content, water holding capacity and color. For each sample, two aliquots of intact meat were scanned using FT-NIRs Antaris™ II Analyzer. Mathematical pre-treatments (Multiplicative Scatter Correction, Standard Normal Variate, 1st and 2nd derivate) were applied and partial least square regression was used on the average spectrum. Results were evaluated in terms of coefficient of regression and root mean square errors in calibration (R2-RMSE) and validation (Rv2-RMSEV), as well as in terms of residual prediction deviation (RPD). Equations were developed in full spectral range because optimisation of the spectral range did not improve the results. Calibration results obtained R2 values between 0.76 and 0.79 for colour parameters and RMSE between 0.7 and 1.9. Myoglobin content achieved a R2 value of 0.62 whereas water holding capacity of 0.73. Warner Bratzler Shear Force obtained better calibration results than Texture Profile Analysis (0.79 and 0.70 respectively). R2 were lower and RMSEV were higher in validation compared to calibration. Furthermore, RPD in calibration was always higher than 1.5, except for myoglobin, indicating that the use of NIRS on intact fresh meat have the potential to be used for classifying the results into different classes.