Salt-Induced Changes in Pork Myofibrillar Tissue Investigated by FT-IR Microspectroscopy and Light Microscopy

Abstract

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.

Influence of Linoleic Acid-Induced Oxidative Modification on Gel Properties of Myofibrillar Protein from Silver Carp (Hypophthalmichthys molitrix) Muscle

“…For OLA-MP, increasing addition of OLA caused continuous decrease of amino acid side, resulting in a significant decrease in arginine. Band at 1639 cm −1 is an indicator for tightly bound water [30]. As can be seen, increasing addition of OLA caused a continuous increase of bound water in percentage, consistent with the increase in WHC (Fig.…”

Influence of linoleic acid-induced oxidative modifications on physicochemical changes and in vitro digestibility of porcine myofibrillar proteins

“…Ten bands were determined, similar to the previous studies (B€ ocker, Ofstad, Bertram, Egelandsdal, & Kohler, 2006;Sun, Zhou, Sun, & Zhao, 2012;Zhou, Zhao, Su, et al, 2014). Amount of each secondary structural element given in percentage terms of the control and oxidized MPs are specifically shown in Table 1.…”

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.…”