Scientific Publications with referee

Influence of aging and salting on protein secondary structures and water distribution in uncooked and cooked pork. A combined FT-IR microspectroscopy and 1H NMR relaxometry study.

 

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 en 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 omfattener aggregering av proteiner en DFD og normal kvalitet. Studien indikerer en bra sammenheng mellom forandringer i T2 relaksasjons tider av vann protoner og proteinenes sekundærstruktur som detektert med FT-IR mikrospektroskopi.

Facts

Year 2006
Abstract Fourier transform infrared (FT-IR) microspectroscopy and low-field (LF) proton NMR transverse relaxation measurements were used to study the changes in protein secondary structure and water distribution as a consequence of aging (1 day and 14 days) followed by salting (3%, 6%, and 9% NaCl) and cooking (65 °C). An enhanced water uptake and increased proton NMR relaxation times after salting were observed in aged meat (14 days) compared with nonaged meat (1 day). FT-IR bands revealed that salting induced an increase in native â-sheet structure while aging triggered an increase in native R-helical structure before cooking, which could explain the effects of aging and salting on water distribution and water uptake. Moreover, the decrease in T2 relaxation times and loss of water upon cooking were attributed to an increase in aggregated â-sheet structures and a simultaneous decrease in native protein structures. Finally, aging increased the cooking loss and subsequently decreased the final yield, which corresponded to a further decrease in T2 relaxation times in aged meat upon cooking. However, salting weakened the effect of aging on the final yield, which is consistent with the increased T2 relaxation times upon salting for aged meat after cooking and the weaker effect of aging on protein secondary structural changes for samples treated with high salt concentration. The present study reveals that changes in water distribution during aging, salting, and cooking are not only due to the accepted causal connection, i.e., proteolytic degradation of myofibrillar structures, change in electrostatic repulsion, and dissolution and denaturation of proteins, but also dynamic changes in specific protein secondary structures.
Reference Wu, Z., Bertram, H.C., Kohler, A., Böcker, U., Ofstad, R., Andersen, H.J. 2007. Influence of aging and salting on protein secondary structures and water distribution in uncooked and cooked pork. A combined FT-IR microspectroscopy and 1H NMR relaxometry study. Journal of Agricultural and Food Chemistry, Vol 54, No 22, pp 8589-8597.
Publisher Journal of Agricultural and Food Chemistry,

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  • Achim Kohler

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