For FTIR spectroscopic analyses, cryo-sections, 10 µm in thickness, parallel to those used for histological examination were sectioned and mounted on BaF2 slides. FTIR spectra were acquired with a PerkinElmer Spectrum Spotlight 400 FTIR system (PerkinElmer, Buckinghamshire, UK) using the point function. The size of each point was 13 x 41 µm. All spectra were collected in transmission mode in the mid-infrared region between 4000 and 750 cm -1 with 32 scans per pixel and a spectral resolution of 4 cm -1 . Before each spectrum was recorded, a background spectrum of the BaF2 was obtained. A minimum of ten spectra were obtained in the continuous myofibrillar matrix and six for the muscle fibers. Large variations between the spectra in the protein matrix meant that more spectra were recorded for the matrix than for the muscle fibers. Areas rich in collagen and fat were avoided. Based on visual inspection spectra dominated by spectral signatures related to fat were removed prior to data analysis. To increase the resolution of the peaks, the second derivative was calculated by using the Savitzky-Golay algorithm with a window size of eleven smoothing points, and thereafter for normalization, extended multiplicative signal correction (EMSC) was applied . Spectra for both the myofibrillar matrix and for the muscle fibers were averaged in the range 1700-1500 cm -1 (amide I / II) and used for presentation, while the total number of 192 spectra, was utilized for the Principal Component Analysis (PCA). The ratio between αhelical structures and aggregated β-sheets was calculated as the ratio between the area in the range 1658-1652 cm -1 and the area in the range 1628-1622 cm -1 according to the method described by Perisic et al. . However, a more restricted range of wavenumbers was used; bands that occur in the area between 1652 and 1658 cm -1 are assigned to α-helical structures and non-hydrogenated C=O groups while bands between 1622 and 1628 cm -1 are assigned to C=O groups involved in aggregated β-sheets. In the second derivative spectra, peaks appear negative; to get positive values, the spectra were multiplied by (-1). Since intensity values of some the bands in the second derivative spectra were positive and thus became negative, 0.1 was added to all the 192 spectra. In this way all the spectra were converted to positive values to obtain appropriate values of area ratios.