Origin of static magnetic field induced quality improvement in sea bass (Lateolabrax japonicus) during cold storage: Microbial growth inhibition and protein structure stabilization

Carvacrol-loaded nanoemulsions stabilized by soy protein isolate / chitooligosaccharide conjugates inhibited the oxidation and conformational variations of myofibrillar proteins in refrigerated sea bass (Lateolabrax maculatus)

Soy isolate protein / chitooligosaccharide (SPI/COS) glycosylated conjugates was prepared and employed as an emulsifier to stabilize carvacrol-loaded nanoemulsions (CNE-SPI/COS). The effects of CNE-SPI/COS on the oxidation and aggregation of myofibrillar protein (MPs) from sea bass (Lateolabrax maculatus) were investigated. Samples were immersed in sterile water (CK), SPI/COS solution and CNE-SPI/COS solution, respectively, follow by a 15-day refrigerated storage. MPs were extracted from fish fillets at 3-day intervals, then assessed for the oxidation degree and conformational changes in MPs, as well as structural variations in myofibrils. Compared with the CK group, the results obtained from protein oxidation assessment clarified that the oxidation and aggregation of MPs was significantly reduced by the CNE-SPI/COS treatment, as evidenced by the higher total sulfhydryl content and Ca2+-ATPase activity and lower surface hydrophobicity. Conformational analysis of MPs showed that CNE-SPI/COS was effective in maintaining the ordered secondary structure of MPs and reducing the exposure of hydrophobic residues in the hydrophobic core of the tertiary structure. In addition, CNE-SPI/COS was found to be effective in protecting the microstructure of muscle fibers and myofibrils in fish fillets. These results suggest that CNE-SPI/COS can be a promising method to prevent protein oxidation and aggregation in fish.

Exploring the role of static magnetic field in supercooling storage from the viewpoint of meat quality and microbial community

In order to explore the application prospects of static magnetic field (SMF) combined with supercooling in meat preservation, this study proposed a novel method of supercooling assisted by a stationary magnetic field (SMF + supercooling) for the preservation of chilled pork, evaluating its cooling rate and quality changes (e.g., water holding capacity, color, pH, and TVB-N), as well as the evolution trend of the microbiota. The results showed that SMF + supercooling significantly (P < 0.05) improved the cooling rate of pork. Compared to chilling and supercooling, SMF + supercooling significantly delayed the increase of TVB-N and TVC on the 12th day of storage (P < 0.05). SMF + supercooling treatment achieves the maintenance of pork water-holding capacity by inhibiting water migration, reducing drip loss, cooking loss, and centrifugal loss of pork. The 16S rDNA bacteria flora analysis demonstrated that SMF + supercooling treatment reduced the relative abundance of spoilage bacteria such as Acinetobacter, Streptococcus, and Pseudomonas, delaying the deterioration of pork quality caused by microbial growth. The SMF + supercooling treatment can be considered a novel refrigeration preservation method that delays the deterioration of pork quality and extends its shelf life.

Effect of brine concentration on the quality of salted large yellow croaker during processing and refrigeration

This study aimed to evaluate the effect of brine concentrations (4%, 8%, 12%, 16%) on the quality of salted large yellow croakers. During the wet salting processing, increased salinity inhibited myogenic fibers swelling and extracellular space expansion, and resulted in lower water content and higher salt content of salted large yellow croaker products. During refrigeration of salted large yellow croakers at 4 °C for 24 days, SDS-PAGE patterns showed that high salinity slowed down the degradation of proteins, which was further confirmed by changes in free amino acids (FAAs) and biogenic amine contents. The increases in K value, total volatile basic nitrogen (TVB-N) content, total viable counts (TVC) and the deterioration in sensory were delayed by increasing salinity. Notably, high salinity enhanced malondialdehyde (MDA) accumulation. The results suggested that high salinity inhibited tissue structure destruction, microbial growth, protein degradation and freshness reduction, but accelerated lipid oxidation of salted large yellow croakers.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-024-01573-5.

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.