The 1655 cm -1 band has previously been assigned to C=O stretching vibrations of native αhelical structure in pork muscle myofibrillar proteins . The bands at 1628 and 1622 cm - 1 are most pronounced in the cooked samples and are most likely related to denatured and aggregated myofibrillar proteins having a larger amount of aggregated β-sheet structures . To reveal structural differences among the different emulsified meat formulations, all the spectra were compared using PCA. The score plot (left) and the loading plot (right) of the first and second principal component of the PCA of the amide I and II region from 1700 to 1500 cm -1 are shown in Figure . The score plot proved that the samples were essentially clustered according to process (uncooked vs cooked); PC1 explained 92% of the variation. The corresponding loading plot confirmed that the difference between uncooked and cooked samples was mainly related to the bands at about 1655 cm -1 and at about 1624 cm -1 . PC2, which explained 3% of the variation, was mainly affected by the structural differences between the myofibrillar proteins that makes up the muscle fibers and those that are solubilized by NaCl and make up the myofibrillar matrix. The difference was most pronounced in the cooked samples (Figure , left). The loading plot for PC2 indicates that the cooked fibers are positively correlated to the bands at about 1624 cm -1 representing aggregated β-sheet structures. This can mean that the myofibrillar proteins of the fibers are somewhat more aggregated than the salt-solubilized proteins.