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The study investigated the properties of gels from Japanese Spanish mackerel (Scomberomorus niphonius) (JSM) surimi received conventional washing (CW) or alkaline-saline washing (AW) and un-washing (UW). AW gel exhibited the highest breaking force and deformation as well as water-holding capacity, but CW gel only had higher breaking force than UW gel. Low-field NMR analysis showed that peak P in AW gel was shifted to higher relaxation time and the areas of peak P and P in AW gel were higher than those in UW and CW gels. Compared with UW gel, network structure of AW gel was more continuous with many tiny voids, but CW gel microstructure showed partially uneven area with large voids. SDS-PAGE showed that band intensity of myosin heavy chain attenuated more in AW gel than in UW and CW gels in nonreducing electrophoresis and it recovered more pronounced in reducing electrophoresis. Solubility attributed to hydrophobic interaction, hydrogen and disulfide bonds increased in CW and AW gels. AW gel gave stronger bitterness and aftertaste A while CW gel showed heavier sourness, astringency, and aftertaste B than UW gel. Results suggest that AW improved physiochemical properties of gel and preserved a closer taste pattern to UW gel. It is recommended for JSM surimi producing. PRACTICAL APPLICATIONS: Surimi food has great potential due to its convenience, elasticity, and nutritional value. Japanese Spanish mackerel (JSM), a popular fish species in China, is widely used for producing surimi food, such as fish ball, dumpling, and sausage. Washing is a practical way to improve its gel properties. This study investigated the gel strength, water status, protein pattern, molecular interactions, microstructure, color, and taste of gels from JSM surimi received conventional washing or alkaline-saline washing and un-washing. Some practical information of effects of washing on gel properties was obtained. These results provide supports to the gel properties improvement by appropriate washing for JSM.

The morphology and particle size of nanofillers have specific effects on their micro-distribution parameters in the polymer matrix and macro-properties of composites. In this study, bismuth ferrite nanoparticles (BFO) with different particle sizes were prepared by the sol-gel route, and bismuth ferrite nanofibers (fBFO) were synthesized by electrospinning method, then were blended with epoxy resin as a filler to prepare the epoxy composites with multiple filler concentrations. The morphology and crystal structure of the filler were characterized by SEM and XRD. The effect of filler morphology and particle size on the surface insulation of composites was studied. We found that fBFO nanofibers have better dispersion in epoxy matrix, and fBFO/EP composites have more excellent surface insulation properties. Meanwhile, as the particle size of the filler increases, the flashover voltages of the BFO/EP composites increase. Finally, the simulation model of electric field inside EP composites were established and the trap distribution was calculated by isothermal surface potential decay method. The influence mechanism of filler morphology and particle size on the surface insulation properties of EP composites was further analyzed. BFO particles and nanofibers as fillers blended with epoxy resin have a great engineering application potential.

Myofibrillar protein (MFP) of Japanese seerfish (JS) was oxidized by Fenton system (1, 4, 8, 16 mM H2O2 for 0, 2, 4, 6 hr). After oxidation, α‐helix ratio and sulfhydryl content of MFP declined along with the increased carbonyl and dityrosine levels. Bromophenol blue bound in MFP under 1 mM H2O2 slightly increased. Polymers together with attenuated myosin heavy chain in protein pattern were observed. Compared with non‐oxidized MFP, storage modulus (G′) of MFP subjected to 1 mM H2O2 for 4 hr increased while that of MFP exposed to 16 mM H2O2 declined. When treated with microbial transglutaminase (MTG), mildly oxidized (1 mM H2O2, 2 hr) MFP showed higher G′ while heavily oxidized (16 mM H2O2, 2 hr) MFP had lower G′ than control. Oxidation showed pronounced influences on physiochemical and gelling properties of JS MFP and the oxidation extent affected MTG role on it. Practical applications Protein oxidation occurs extensively in muscle and exerts great influences on muscle food quality. JS is widely used for producing gel food in China. Its muscle also contains oxidation initiators such as H2O2, hemoglobin and lipids, increasing the susceptibility to protein oxidation. Results of the study exposed the effects of hydroxyl radical oxidation on physiochemical and gelling properties of JS MFP. It provides strategic support to improve gel properties of MFP by manipulating oxidation.