Determination of hydroxyproline in cured pork sausages and dry cured beef products by NIRS technology employing a fibre–optic probe

In the present work a study was made of the use of near infra-red spectroscopy (NIRS) technology with a remote reflectance fibre–optic probe for the analysis of hydroxyproline in cured pork sausages (salchichón and chorizo) and dry cured beef (cecina). The presence of the amino acid hydroxyproline was used as an analytical criterion to assess the amount of collagen from connective tissues versus lean meat (muscle). The fibre–optic probe was placed directly on the sample with no previous treatment or manipulation. The regression method employed was that of modified partial least squares (MPLS). The equation developed for a total of 80 samples (salchichón, chorizo and cecina) allowed the determination of the hydroxyproline content within a range of 0–0.74%. The multiple correlation coefficient (RSQ) and standard error of prediction corrected (SEP(C)) obtained were respectively 0.772 and 0.05%. The predicted values of hydroxyproline in unknown samples using NIRS technology and applying the fibre–optic probe directly on the sample without previous treatment were comparable to those obtained using the chemical method.