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To inhibit the melanization of shrimp (Penaeus vannamei) and improve its freezing quality, different intensities of static magnetic field (MF) were used to assist freezing, with MF intensities of 0, 2, 4, 6, and 8 mT. The effects of different freezing treatments on the freezing parameters, microstructure, enzyme activities, quality indicators, and bacterial communities were investigated. The results indicated that the phase transition and total freezing time significantly decreased under the action of 2 mT MF (8.4% and 15.4%, p < 0.05). Meanwhile, 2 mT treatment significantly reduced polyphenol oxidase and Ca2+-ATPase activities (45.2% and 99.1%), drip loss (46.0%), color change (24.4% and 20.9%), myofibril fragmentation index (20.4%), thiobarbituric acid reactive substances (30.6%) and total viable count (24.2%) (p < 0.05); improved hardness and chewiness (32.2% and 33.3%) (p < 0.05); and protected muscle microstructure compared to common freezing. Isolation and examination of pathogenic bacteria revealed that the 2 mT MF significantly reduced the number of Vibrio parahaemolyticus (50.3%) (p < 0.05). High-throughput sequencing analysis also demonstrated that a 2 mT magnetic field is preferable for assisting in the freezing process of Penaeus vannamei. It effectively decreases the microbial richness and diversity of shrimp, along with the abundance of spoilage bacteria such as Vibrio and Pseudoalteromonas. • Magnetic field accelerated the freezing rate of the shrimp. • Low-intensity magnetic field significantly inhibited the melanization of shrimp. • The suitable magnetic field intensity on freezing shrimp was 2 mT. • Vibrio and Pseudoalteromonas were inhibited at a 2 mT magnetic field intensity. [ABSTRACT FROM AUTHOR]

Electron beam irradiation (EBI) can effectively kill microorganisms that cause food decay and thus, prolong the shelf life of food. However, different doses of EBI on the impact of Portunus trituberculatus microbial community structure remain to be seen. This study adopted high-throughput sequencing technologies to compare the effect of different doses of EBI on the microbial community structure of the swimming crab and found that the crab microbial community structure was changed significantly upon treatment with different doses of EBI. We combined alpha and beta diversity analysis, relative abundance analysis of species, and linear discriminant analysis effect size analysis, and our results focused on Psychrilyobacter , Clostridium , Vagococcus , Psychrobacter , and Carnobacterium. In addition, the richness and diversity of microorganisms initially decreased and then increased with the increasing of radiation dose. The results showed that the minimum dose of EBI was 6 kGy. This study provides a theoretical basis for the preservation of crabs. [Display omitted] • The effects of EBI on the microflora of Portunus trituberculatus were studied by 16S rRNA. • Bacteria richness and diversity decreased firstly and then increased with increasing EBI dose. • EBI may inhibit the growth of Pseudomonas bacteria to prevent the occurrence of BPS. • Psychrobacter dominated the P. trituberculatus after 6 kGy dose of EBI. [ABSTRACT FROM AUTHOR]