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Myowater dynamics and protein secondary structural changes as affected by heating rate in three pork qualities: A combined FT-IR microspectroscopic and 1H NMR relaxometry study.

Wu, Z., Bertram, H.C., Böcker, U., Ofstad, R. og Kohler, A.

Effekten av langsom og rask oppvarming til 65 °C på vann foredelingen og proteinenes sekundærstruktur av tre forskjellige kvaliteter av grisekjøtt (DFD, PSE og normal) ble analysert ved hjelp av NMR spektroskopi og FT-IR mikrospektroskopi.

Rask oppvarming fører til et høyere vanntap spesielt i PSE kjøttet og gir forandringer i myofibrillært vann (forandret T21 fordeling). Samtidig gir rask oppvarming en økt andel av "random” strukturer og β-plater mens andelen av native α-heliks strukturer minker. I tillegg vises at PSE kvalitet kjøttet gjennomgår en omfattende aggregering av proteiner enn DFD og normal kvalitet. Studien indikerer en bra sammenheng mellom forandringer i T2 relaksasjonstider av vannprotoner og proteinenes sekundærstruktur som detektert med FT-IR mikrospektroskopi.

Nøkkeldata

Årstall 2007
Abstract The objective of this study was to investigate the influence of heating rate on myowater dynamics and protein secondary structures in three pork qualities by proton NMR T2 relaxation and Fourier transform infrared (FT-IR) microspectroscopy measurements. Two oven temperatures at 100 °C and 200 °C corresponding to slow and fast heating rates were applied on three pork qualities (DFD, PSE, and normal) to an internal center temperature of 65 °C. The fast heating induced a higher cooking loss, particularly for PSE meat. The water proton T21 distribution representing water entrapped within the myofibrillar network was influenced by heating rate and meat quality. Fast heating broadened the T21 distribution and decreased the relaxation times of the T21 peak position for three meat qualities. The changes in T21 relaxation times in meat can be interpreted in terms of chemical and diffusive exchange. FT-IR showed that fast heating caused a higher gain of random structures and aggregated â-sheets at the expense of native R-helixes, and these changes dominate the fast-heating-induced broadening of T21 distribution and reduction in T21 times. Furthermore, of the three meat qualities, PSE meat had the broadest T21 distribution and the lowest T21 times for both heating rates, reflecting that the protein aggregation of PSE caused by heating is more extensive than those of DFD and normal, which is consistent with the IR data. The present study demonstrated that the changes in T2 relaxation times of water protons affected by heating rate and raw meat quality are well related to the protein secondary structural changes as probed by FT-IR microspectroscopy.
Referanse Wu, Z., Bertram, H.C., Böcker, U., Ofstad, R., Kohler, A. 2007. Myowater dynamics and protein secondary structural changes as affected by heating rate in three pork qualities: A combined FT-IR microspectroscopic and 1H NMR relaxometry study. Journal of Agricultural and Food Chemistry, Vol 10, pp 3990-3997.
Utgiver Journal of Agricultural and Food Chemistry,

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