title: Analyzing pH-induced changes in a myofibril model system with vibrational and fluorescence spectroscopy.
abstract: The decline of pH and ultimate pH in meat postmortem greatly influences meat quality (e.g. water holding capacity). Four spectroscopic techniques, Raman, Fourier transform infrared (FT-IR), near infrared (NIR) and fluorescence spectroscopy, were used to study protein and amino acid modifications to determine pH-related changes in pork myofibril extracts at three different pH-levels, 5.3, 5.8 and 6.3. Protonation of side-chain carboxylic acids of aspartic and glutamic acid and changes in secondary structure, mainly the amide I-III peaks, were the most important features identified by Raman and FT-IR spectroscopy linked to changes in pH. Fluorescence spectroscopy identified tryptophan interaction with the molecular environment as the most important contributor to changes in the spectra. NIR spectroscopy gave no significant contributions to interpreting protein structure related to pH. Results from our study are useful for interpreting spectroscopic data from meat where pH is an important variable.
authors.affiliation: Nofima AS, Osloveien 1, 1430 Ås, Norway. Electronic address: petter.andersen@nofima.no.
authors.forename: Petter Vejle
authors.initials: PV
authors.lastname: Andersen
authors.affiliation: Nofima AS, Osloveien 1, 1430 Ås, Norway. Electronic address: eva.veiseth-kent@nofima.no.
authors.forename: Eva
authors.initials: E
authors.lastname: Veiseth-Kent
authors.affiliation: Nofima AS, Osloveien 1, 1430 Ås, Norway. Electronic address: jens.petter.wold@nofima.no.
authors.forename: Jens Petter
authors.initials: JP
authors.lastname: Wold
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000818:Animals; D006863:Hydrogen-Ion Concentration; D008954:Models, Biological; D009124:Muscle Proteins / Q000032:analysis; D009210:Myofibrils / Q000378:metabolism*; D017433:Protein Structure, Secondary; D000069466:Red Meat / Q000032:analysis*; D013050:Spectrometry, Fluorescence; D017550:Spectroscopy, Fourier Transform Infrared; D019265:Spectroscopy, Near-Infrared; D013552:Swine; D014364:Tryptophan / Q000032:analysis
chemical_list: D000596:Amino Acids; D009124:Muscle Proteins; D014364:Tryptophan
keywords: Fluorescence; Proteins; Vibrational spectroscopy; Water-holding capacity; pH