Gelation of salted myofibrillar protein under malondialdehyde-induced oxidative stress

This study presented the formation of cold-set myofibrillar protein gel under oxidative stress originated from malondialdehyde (MDA) in the presence of 0.6 M NaCl. Heating procedure was also applied for further evaluation of gel properties. Protein carbonyl content was used to evaluate protein oxidation. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) was performed to explain the formation of the gel. Gel properties were compared in range of MDA/NaCl concentration with use of gel strength, water-holding capacity (WHC), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) measurements. Results confirmed the occurrence of protein oxidation in the system applied. Myosin was greatly involved in gel formation through non-disulfide covalent bond. Meanwhile, significant improvements in gel strength, WHC, the network structure of highly porous with well-defined shapes were observed with increasing addition of MDA/NaCl. Furthermore, with the addition of MDA no more than 10 mM, the gel formed in the presence of 0.6 M NaCl was stable to heat treatment, while the higher MDA could cause gel collapse, which was believed to be due to the excessive covalent bond existed. The gelation procedure in this study involved simultaneous protein oxidation and internal cross-linking. The gel was formed on the premise of the swelling of myofibrillar protein under certain ionic strength and the intermolecular cross-links formed via MDA.