Salt-induced changes in pork myofibrillar tissue investigated by FT-IR microspectroscopy and light microscopy.
FT-IR microspectroscopy and light microscopy were used to investigate pork muscle musculus semitendinosus samples, taken from three animals, that were subjected to brine salting at different concentrations (0.9, 3, 6, and 9% NaCl). Differences in spectral characteristics and in microstructure were observed in meat from animals differing in initial pH and varying salt concentrations. The FT-IR data displayed changes in the amide I region from 1700 to 1600 cm(-1). This spectral range was analyzed by principal component analysis (PCA) and partial least-squares regression (PLSR). These methods revealed correlations between the spectral data and the different animals, salt content, moisture content, pH value, and myofiber diameter. A shrinking share of alpha-helical components was related to an increase in salt concentration in the muscle. At the same time, a greater share in nonhydrogenated C=O groups (1668 cm(-1)) was related to an increase in salt concentration in the meat. The share of aggregated beta-strands differed with respect to the different animals but was not influenced by salt concentration. The meat at higher pHs (>6) had less aggregated beta-strands than that at lower pHs (5.6-5.7). It could be demonstrated that simultaneous with changes in microstructure, pH value, salt, and moisture content were alterations in the protein amide I region as measured by FT-IR microspectroscopy, revealing a relationship between these biophysical and chemical parameters and secondary protein structure attributes.
Böcker
Ulrike
U
Centre for Biospectroscopy and Data Modelling, Matforsk AS, Norwegian Food Research Institute, Osloveien 1, N-1430 As, Norway. ulrike.bocker@matforsk.no
Ofstad
Ragni
R
Bertram
Hanne Christine
HC
Egelandsdal
Bjørg
B
Kohler
Achim
A
D000818:Animals; D006863:Hydrogen-Ion Concentration; D008460:Meat / Q000032:analysis; D009124:Muscle Proteins / Q000032:analysis / Q000737:chemistry; D018482:Muscle, Skeletal / Q000737:chemistry / Q000187:drug effects / Q000648:ultrastructure*; D009210:Myofibrils / Q000737:chemistry* / Q000187:drug effects / Q000648:ultrastructure*; D017433:Protein Structure, Secondary; D012965:Sodium Chloride / Q000008:administration & dosage / Q000494:pharmacology*; D017550:Spectroscopy, Fourier Transform Infrared; D013552:Swine
D009124:Muscle Proteins; D012965:Sodium Chloride