Dielectric barrier discharge pretreatment combined with magnetic field-assisted partial freezing: A novel strategy for enhancing the preservation quality of tuna.

Dielectric barrier discharge (DBD) demonstrates great potential in aquatic product preservation due to its strong sterilization capability. However, its application is greatly restricted by oxidative deterioration induced under high-voltage conditions. To address this challenge, this study combined DBD pretreatment with magnetic field (MF)-assisted partial freezing (PF) to improve the quality of tuna fillets. After 12 days of storage, the combined treatment (DBD-MF-PF) effectively inhibited color deterioration and microbial growth in the fillets. Compared with cold storage (CS) and single DBD pretreatment (DBD-CS), DBD-MF-PF increased the a* values of fillets by 72.8% and 57.3%, respectively and reduced total viable counts by 62.7% and 58.3%, respectively. MF application alleviated muscle fiber damage and moisture loss, reducing drip loss by 35.8% compared with DBD-PF. Furthermore, MF-assisted PF mitigated the initial oxidative damage induced by DBD, with TBARS decreasing by 62.2% and 17.8% compared with DBD-CS and DBD-PF, while sulfhydryl content increased by 54.1% and 15.5%. Protein analysis showed that DBD pretreatment initially led to slight local unfolding of myofibrillar proteins (MP), as indicated by increased surface hydrophobicity and β-turn content. MF-assisted PF delayed MP unfolding, reduced unfavorable conformational transitions, and maintained higher fluorescence intensity. Meanwhile, DBD pretreatment also inhibited protein degradation, and DBD-MF-PF further exerted a synergistic effect. The TCA-soluble peptide content was 48.91%, 61.80%, and 70.34% lower in DBD-CS, DBD-PF, and DBD-MF-PF, respectively than in CS on day 12. Overall, DBD-MF-PF effectively maintained tuna quality, offering a green and efficient preservation strategy for high-value aquatic products.