The use of Fourier‐transform infrared spectroscopy to characterize connective tissue components in skeletal muscle of Atlantic cod (Gadus morhua L.).

Summary

In the present study, Fourier-transform infrared spectroscopy (FTIR) is inves- tigated as a method to measure con- nective tissue components that are important for the quality of Atlantic cod filets (Gadus morhua L.). The Atlantic cod used in this study origi- nated from a feeding trial, which found that fish fed a high starch diet con- tained relative more collagen type I, while fish fed a low starch (LS) diet contained relative more glycosaminoglycans (GAGs) in the connective tissue. FTIR spectra of pure commercial collagen type I and GAGs were acquired to identify spectral markers and compare them with FTIR spectra and images from connective tissue. Using principal component analysis, high and LS diets were separated due to colla- gen type I in the spectral region 1800 to 800 cm −1 . The spatial distribution of colla- gen type I and GAGs were further investigated by FTIR imaging in combination with immunohistoch emistry. Pixel-wise correlation images were calculated between preprocessed connective tissue images and preprocessed pure components spectra of collagen type I and GAGs, respectively. For collagen, the FTIR images reveal a collagen distribution that closely resembles the collagen distribution as imaged by immunohistoch emistry. For GAGs, the concentration is very low. Still, the FTIR images detect the most GAGs rich regions.