Gelation properties of myofibrillar protein (MP)/wheat gluten (WG) induced by glutamine transaminase (TGase) were studied. Results showed that the inclusion of transglutaminase increased the gel strength, water-holding capacity (WHC), and nonfreezable water (Wnf) of MP/WG mixture. Circular dichroism (CD) analysis showed that the β-sheet and random coil content of the MP/WG treated with TGase addition increased by 12.1% and 3.7%, while the α-helix and β-turn content decreased by 14.2% and 1.8%. Rheological measurements showed that TGase induced higher energy storage modulus value during the MP/WG gel heating-cooling cycle. the hydrogen bond and hydrophobic interaction content of the MP/WG gels increased by 80 and 120 ug/L, and the disulfide bond decreased by 200 ug/L, with TGase addition was increased from 0 to 120 U/g protein. Scanning electron microscope (SEM) showed that MP/WG gel with TGase had uniform and dense network structure. PRACTICAL APPLICATION: The properties of myofibrillar/wheat gluten gel induced by TGase crosslinking was studied. The gel structure and water holding capacity of MP/WG were improved by the cross-linking of TGase. The study of the gel properties of MP/WG induced by TGase crosslinking also can provide a theoretical basis for analyzing the effect of TGase on the application of gluten protein in complex meat emulsion system.

The objective of this study was to evaluate relationship with aggregation, secondary structures and gel properties of pork myofibrillar protein with different sodium chloride (1%, 2% and 3%). When the sodium chloride increased from 1 to 3%, the active sulfhydryl, surface hydrophobicity, hardness and cooking yield of myofibrillar protein were increased significantly (p < 0.05), the particle size, total sulfhydryl and Zeta potential were decreased significantly (p < 0.05), these meant the aggregations of pork myofibrillar protein were decreased. The changes of proteins aggregation induced the strongest intensity band of Amide I shifted up from 1660 cm-1 to 1661 cm-1, meanwhile, the β-sheet structure content was increased significantly (p < 0.05) with the sodium chloride increased. From the above, the lower proteins aggregation and higher β-sheet structure content could improve the water holding capacity and texture of pork myofibrillar protein gel.

Protein oxidation during chilling and frozen storage has recently attracted great attention due to its consequences on protein solubility and functionality. In this study, the effects of kappa-carrageenan oligosaccharides on myofibrillar protein oxidation in peeled shrimp (Litopenaeus vannamei) during frozen storage were investigated by assessing the content of the carbonyls, total sulfhydryl, dityrosine, and surface hydrophobicity. We also examined the means of antioxidant activity in vitro, degradation of muscle proteins, and integrity of tissue structure. Our data revealed that in vitro carrageenan oligosaccharides exhibited good capacities of OH, O2-, and DPPH· scavenging and Fe2+-chelating activity. Chemical analyses showed that frozen storage increased susceptibility of myofibrillar proteins to frozen oxidation. We found that the incorporation of carrageenan oligosaccharides during the treatment of the shrimp prior to frozen storage significantly decreased the formation of protein carbonyl and dityrosine, lowered the changes in myofibrillar surface hydrophobicity, and maintained a higher total sulfhydryl content when compared with the water-treated samples (control). Additionally, the results of protein degradation and tissue structure confirmed that these antioxidant oligosaccharides exhibited marked effects on stability of muscle proteins and effectively inhibited the degradation/oxidation of muscle proteins during frozen storage. Overall, the contribution of the antioxidant activities played an important role in cryoprotective effects of carrageenan oligosaccharides on frozen shrimp. Further application of these findings might maintain better quality and extend the commercialization of refrigerated products.

The objective of this study was to investigate the microstructure, protein denaturation and water holding capacity of lamb pickled under pulse vacuum. Sixty topside samples (M. semimembranosus) were randomly assigned into two groups and cured for 0, 1.5, 3, 4.5 and 6h by pulse vacuum brining (PVB) and atmospheric brining (AB) (control), respectively. The salt content of samples by PVB was about 1% higher than AB from 1.5h to 6h. The water holding capacity was greater for PVB group before 4.5h (P<0.05). The actomyosin was dissolved more after being pickled for 1.5, 3, 4.5 and 6h under PVB. The myofibril swelled more intensively and myofibril diameters with PVB were significantly larger than that of AB (P<0.05). In summary, pulse vacuum brining can be used to improve the brining efficiency, promoting the actomyosin dissociation and improving the water holding capacity of lamb, which will be a potential technology to be used in practice.

The effect of trehalose on the denaturation of weever (Lateolabrax japonicus) myofibrillar protein during frozen storage at -18 °C for 90 d was investigated. Trehalose (2.5-10 g dry weight) was added to 100 g of myofibrillar protein, and changes in the Ca(2+)-adenylpyrophosphatase (ATPase) activity, solubility, sulfhydryl content, and unfrozen water content of myofibrils were examined during frozen storage. Ca(2+)-ATPase activity and myofibrillar protein solubility decreased gradually during frozen storage at -18 °C upon addition of trehalose. By contrast, Ca(2+)-ATPase activity and myofibrillar protein solubility in the control group dropped drastically during the first 45 d of storage and then further decreased gradually for up to 90 d of storage, indicating a biphasic denaturation pattern. Trehalose addition significantly increased sulfhydryl and unfrozen water contents in the myofibrillar protein of the treatment groups compared with that of the control group (p<0.05) during frozen storage at -18 °C.