Investigation of the changes in lipid profiles induced by hydroxyl radicals in whiteleg shrimp (Litopenaeus vannamei) muscle using LC/MS-based lipidomics analysis.

The oxidative effects of hydroxyl radical on the alterations of lipid profiles were investigated in shrimp muscle. Chemical results indicate peroxide value (PV) and thiobarbituric acid index (TBA-i) value in oxidation-treated shrimp significantly increased with oxidation time, and hydroxyl radical concentration increased, compared with those of in fresh samples. It was assumed that radical attack might induce lipid decomposition, backbone cleavage, and/or side-chain modifications. LC/MS-based lipidomics analysis revealed 835 lipids in shrimp assigned to 27 lipid classes, including 219 PCs and 98 CLs. In total, 86 and 34 differentially abundant lipids (DALs) accumulated at lower and higher levels, respectively, were identified in OS, compared with that in FS. This indicates hydroxyl radical attack altered the lipidomics profiles of shrimp muscle to a large extent. Furthermore, DALs, including CL 62:2, PC 38:3, and PE 34:9, could be considered as promising biomarkers to distinguish fresh and oxidation-treated shrimp products.

The differences of muscle proteins between neon flying squid (Ommastrephes bartramii) and jumbo squid (Dosidicus gigas) mantles via physicochemical and proteomic analyses.

Neon flying squid (OB) and jumbo squid (DG) mantles were evaluated to reveal the similarities and differences in their physicochemical features and protein abundances. Microstructural results indicated that the OB mantle exhibited numerous myofibril fragments and disordered microstructures after frozen storage compared with DG tissues. Chemical analysis suggested that freezing resulted in a rapid decrease in myofibrillar protein (MP) content, Ca2+-ATPase activity, and total sulfhydryl content, and promoted the increase in carbonyl content of MPs in both OB and DG. While, DG presented better MP stability than OB muscle after 120 days of frozen storage. Label-free proteomic analysis detected 24 down- and 33 up-regulated differentially abundant proteins (DAPs) in OB and DG mantles. Identified DAPs including isocitrate dehydrogenase and malic enzyme initiated a rapid decrease in the MP properties in OB samples. Moreover, DAPs were related to cytoskeleton function, including paramyosin, tropomyosin, and troponin C, which improved the stability of DG in response to freezing-induced changes.

Insights into the similarities and differences of whiteleg shrimp pre-soaked with sodium tripolyphosphate and sodium trimetaphosphate during frozen storage.

In this study, similarities and differences of sodium tripolyphosphate (STPP) and sodium trimetaphosphate (STMP) pre-soaking on the stability of muscle proteins in shrimp were investigated during 12 weeks of frozen storage (-30 °C). The physicochemical analysis indicated significant improvements in the WHC, springiness, chewiness, and thermal stability of STPP and STMP pre-soaked samples when compared to the control. Interestingly, STMP pre-soaking showed better cryoprotective effects than the STPP treatment when the storage period reached the end of the 12 weeks. Furthermore, the label-free based proteomics results indicated that 62 upregulated differentially abundant proteins (DAPs) were detected in STMP when compared to STPP. These identified DAPs specifically included 40S ribosomal proteins, actin-related proteins, heat shock proteins, myosin heavy chain, and tubulin beta chain. Additionally, the gene ontology (GO) and eukaryotic clusters of orthologous group (KOG) analyses verified that the incorporation of STMP molecules enhanced the resistance of cytoskeleton proteins to cold-temperature stress.

Kappa-carrageenan and its oligosaccharides maintain the physicochemical properties of myofibrillar proteins in shrimp mud (Xia-Hua) during frozen storage.

As a popular hot-pot ingredient, Chinese-style shrimp mud (Xia-Hua) is usually transported and stored frozen. However, frozen storage leads to decreased quality of Xia-Hua products caused by the variations in physicochemical and functional properties of myofibrillar proteins (MPs). Κ-carrageenan and its oligosaccharides are reported as antioxidants and antifreeze and can stabilize proteins in whole shrimp, but their effects on MPs in Xia-Hua remain poorly understood. Compared to the control and Na4 P2 O7 treatments, the physicochemical properties of MPs in κ-carrageenan and its oligosaccharides-incorporated Xia-Hua were evaluated during 120 days of frozen storage. The results showed that cold stress increased the susceptibility of MPs to denaturation and oxidation during frozen storage. Carrageenan oligosaccharides maintained the turbidity, emulsifying activity, stability, and foaming capacity of MPs. Oxidation analysis showed that the incorporation of carrageenan oligosaccharides significantly retarded the rapid decrease of Ca2+ -ATPase activity, total sulphydryl and active sulphydryl contents, and also effectively inhibited the increases of carbonyl content and surface hydrophobicity of MPs. Thermal stability results confirmed that the oligosaccharides improved the denaturation temperature and enthalpy of MPs compared to the control, Na4 P2 O7 , and carrageenan treatments. This study suggests that κ-carrageenan and its oligosaccharides maintain the properties of MPs in Xia-Hua during frozen storage. PRACTICAL APPLICATION: The cryoprotection and antioxidant effects of carrageenan oligosaccharides on the stability of MPs in frozen shrimp mud can be used to extend the shelf-life and maintain the quality of frozen Xia-Hua products. Furthermore, it can drive the development of aquatic product health industry, improve the quality and safety of aquatic products, reduce the occurrence of public food safety incidents, and maintain social stability.

Label-free proteomic analysis revealed the mechanisms of protein oxidation induced by hydroxyl radicals in whiteleg shrimp (Litopenaeus vannamei) muscle.

The oxidative effects of hydroxyl radicals derived from a FeCl3/ascorbic acid/H2O2 system on the stability of muscle proteins in peeled shrimp (Litopenaeus vannamei) were investigated. Physicochemical analysis indicated negative effects on the color (a* value), springiness, and pH of shrimp muscle, which appeared to be significantly exacerbated by higher concentrations of generated hydroxyl radicals when compared with the control. The microstructural results confirmed that a radical attack induced the incompact structure and disintegrated myofibers, thereby leading to weakened connective tissues and decreased stability of muscle proteins. Furthermore, label-free proteomic analysis revealed several differentially abundant proteins (DAPs) (i.e., ribosomal protein subunits, putative cytoskeleton proteins, and ion-binding proteins), which were detected and identified in oxidation-treated shrimp when compared with the control. The gene ontology (GO) and eukaryotic clusters of orthologous group (KOG) analyses further confirmed that the active hydroxyl radicals attacked vulnerable amino acids, modified peptide chains, and/or protein structures and/or conformations, which were responsible for a significant decrease in the muscle texture and stability of proteins in oxidation-treated shrimp. This study provides novel insight into the molecular mechanisms of muscle protein changes during oxidation development.