Minjie Cao,Ailing Cao,Jing Wang,Luyun Cai,Joe Regenstein,Yunjie Ruan,Xiuxia Li
In order to evaluate the effects of magnetic nanoparticles plus microwave (MNPMT) or far-infrared (MNPFT) thawing on protein conformation changes and moisture migration of red seabream ( Pagrus major ) fillets, cold storage thawing, microwave thawing, MNPMT, far-infrared thawing and MNPFT were subjected to red seabream fillets. DSC and dynamic rheology were conducted to analyze physicochemical changes. Raman spectra before and after isotope H/D exchange, intrinsic fluorescence and UV second derivative spectra were carried out to explore myofibrillar protein structural changes. Low-field NMR was used to test water migration. SEM was performed to observe fiber microstructure. Results indicated that MNPMT and MNPFT both had a desirable thermal stability and gelation property. Besides, both showed stable protein secondary and tertiary structure. Immobilized water in them also had no significant changes compared with fresh sample. This research provided some novel thawing technologies for application in food industry.
Ultrasound assisted vacuum thawing (UVT) or microwave vacuum thawing (MVT) with red seabream fillets were compared to fresh, chill storage thawing, vacuum thawing, microwave thawing and ultrasound thawing. The thermal stability and gelation properties were studied with DSC and dynamic rheology, respectively. Raman spectra before and after H/D isotope exchange and intrinsic fluorescence were used to measure protein secondary and tertiary structure. Low-field NMR was done to measure water migration. The two thawing techniques both retained actin thermal stability and generally retained more stable tertiary structures than the other thawing methods. MVT showed a desirable viscoelasticity of muscle proteins and UVT had a relatively stable secondary structure. There were no significant changes in free water. Thus, UVT and MVT could be used to improve the physicochemical properties of proteins during thawing of fillets.
Fish cell lines serve as ideal in vitro models for investigating the toxicity of environmental pollutants in fish. In this study, a novel cell line (PmOVC) derived from the ovary of red seabream ( Pagrus major ) was successfully established. Using polystyrene microplastics (PS-MPs)—a typical environmental pollutant—as the test substance, the toxicity sensitivity of the PmOVC cell line was systematically assessed from the dimensions of particle size intake and cell activity. The results showed that the PmOVC cells exhibited robust growth in M199 medium supplemented with 15% FBS at 23°C and high exogenous gene transfection efficiency and showed high sensitivity to the toxic effects of microplastics. Specifically, the smaller the particle size of microplastics, the higher the internalization efficiency of cells, among which 100 nm PS-MPs could be completely endocytosed into the cytoplasm; the concentration of PS-MPs was significantly positively correlated with the apoptosis rate of cells ( R 2 ≥ 0.8). In summary, the established PmOVC cell line provides a critical in vitro tool for in-depth investigation of the toxicological responses and underlying mechanisms of fish to environmental pollutants.
危险品化学品经营许可证（带存储）