Monitoring of denaturation processes in aged beef loin by FT-IR microspectroscopy

Summary

We present the results of a Fourier transform infrared (FT-IR) microspectroscopic study using conventional FT-IR microscopy and FT-IR imaging to detect the denaturation process during four different heating temperatures (raw, 45, 60 and 70C) spatially resolved in bovine cryosections from longissimus dorsi muscle. FT-IR imaging, employing a focal plane array (FPA) detector, which allowed the simultaneous collection of spectra at 4096 pixels, enabled the investigation of the heat-induced changes in the two major meat constituents, i.e. myofibrillar and connective tissue proteins, spatially resolved. The infrared spectra of both compounds revealed that the major spectral changes involved an increase in -sheet and a decrease in -helical structures, which appeared to be much more pronounced for the myofibres than for the connective tissue. Conformational changes in the secondary structures of the proteinscould be correlated to the denaturation temperatures of the major meat proteins, such as myosin, actin and collagen. The intensity of the spectral changes was more pronounced in the periphery than in the centre of the myofibres. Microstructural changes such as transversal shrinkage of the myofibres and widened extracellular spaces occured concomitantely with the spectral changes. The degree of the structural changes may have an impact on both juiciness and texture of the meat. Thus, basic knowledge of the the heatinduced structural changes in meat may help us to optimise the heating procedure and to optimise the sensory properties.