Effects of Ultra-High Pressure on Endogenous Enzyme Activities, Protein Properties, and Quality Characteristics of Shrimp (Litopenaeus vannamei) during Iced Storage

Reducing the allergenicity of tropomyosin in shrimp by covalent conjugation with quercetin and chlorogenic acid

The study aimed to assay the allergenicity of shrimp tropomyosin (TM) following covalent conjugation with quercetin (QR) and chlorogenic acid (CA). The structure of the TM-polyphenol covalent conjugates was examined by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), circular dichroism (CD), fluorescence, differential scanning calorimetry (DSC), and Fourier Transform infrared spectroscopy (FTIR). Potential allergenicity was evaluated using in vitro and in vivo methods. The results showed that QR and CA induced structural changes in TM through aggregation. RBL-2H3 cell results showed that TM-QR and TM-CA covalent conjugates reduced the release of β-hexosaminidase and histamine, respectively. In the mice model, TM-QR and TM-CA covalent conjugates reduced the level of IgE, IgG, IgG1, histamine, and mMCP-1 in sera. Furthermore, the allergenicity was reduced by suppressing Th2-related cytokines (IL-4, IL-5, IL-13) and promoting Th1-related cytokines (IFN-γ). These research findings demonstrate that the covalent binding of TM with QR and CA, modifies the allergenic epitopes of shrimp TM, thereby reducing its potential allergenicity. This approach holds practical applications in the production of low-allergenicity food within the food industry.

Changes in quality characteristics based on protein oxidation and microbial action of ultra-high pressure-treated grass carp (Ctenopharyngodon idella) fillets during magnetic field storage

Ultra-high pressure (UHP) and magnetic field (MF) are emerging food preservation technologies, but the research on the effects of combined treatment (UHP-MF) on aquatic products quality is insufficient. Hence, we explored the effects of UHP-MF treatment on the protein properties, microbial action and quality characteristics of stored grass carp fillets. Results showed that 300 MPa UHP treatment combined with MF storage (UHP300-MF) delayed the protein oxidation of stored fillets by inhibiting the accumulation of protein radical and the formation of lipid pro-oxidation products, thus the quality (texture, color) deterioration caused by oxidation was deferred. Additionally, 16S rDNA bacteria flora analysis revealed that UHP300-MF treatment inhibited the flora activity and diversity of fillets, delayed the protein degradation and quality deterioration caused by microbial action. Overall, UHP300-MF treatment suppressed the lipid and protein oxidation as well as microbial action, retarded the quality deterioration, and prolonged the shelf life of stored fillets.