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

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 degrees C and 200 degrees 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 degrees 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 beta-sheets at the expense of native alpha-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.

Raman spectroscopic determination of structural changes in meat batters upon soy protein addition and heat treatment

“…The protein secondary structural changes observed upon heating (increase in b-sheet structure) are consistent with literature references (Bouraoui et al, 1997;Moosavi-Nasab, All, Ismail, & Ngadi, 2005;Sánchez-González et al, 2008;Herrero et al, 2008b). In this connection, FT-IR spectroscopic studies in meat myofibrillar proteins have shown that the levels of b-sheet structures increase upon heating (Wang & Smith, 1994;Kirschner, Ofstad, Skarpeid, Hp~st, & Kohler, 2004;Böcker, Ofstad, Bertram, Egelandsdal, & Kohler, 2006;Wu et al, 2006;Wu, Bertram, Böcker, Ofstad, & Kohler, 2007). In myofibrillar proteins, complete protein denaturation and aggregation upon heat- 1.…”

Cooking of pork Longissimus dorsi at different temperature and relative humidity values: Effects on selected physico-chemical properties

“…In addition, fast heating was reported to cause severe myofibrillar shortening and decreased sarcomere length and this was associated to higher cooking loss (King et al, 2003). Recently, relations between heating rates, cooking losses and protein changes were more completely established on pork also at a secondary protein structure level by means of combined FT-IR spectroscopy and low-field NMR relaxometry, as higher water depletion induced by faster heating was found to lead to random structure and aggregated b,-sheet as well lower content of a-helical structures (Wu et al, 2007). Thus, it is possible to hypothesize that pork samples showing the highest water loss could be probably subjected to the highest degree of protein denaturation.…”

Effect of Water on the Quality of Dehydrated Products: A Review of Novel Characterization Methods and Hybrid Drying Technologies

“…[12] NMR spectroscopy has been used to measure the water activity in meat as the shape of the T 2 relaxogram is closely linked to changes in the state or structure of water in meat. [15][16][17][18] 1 H-NMR spin-spin relaxation studies have shown that there are ''restricted water'' and ''strongly restricted water'' in living cells. [19][20][21][22] Both types of water possess different dynamic behavior in terms of mobility.…”