Abstract:To investigate the effect of ultra-high pressure （UHP） treatment on the quality of grouper during refrigeration， this experiment used grouper as the raw material. The study examined the effects of different UHP conditions （100， 200， 300， 400， 500 MPa， and maintained at room temperature for 5 min） on the total bacterial count， total volatile base nitrogen （TVB-N） content， total sulfhydryl content， pH value， thiobarbituric acid （TBA） value， texture， and color of grouper during cold storage at 4 ℃ （0-18 d）. The results showed that treatments of 300 MPa and above significantly reduced the total bacterial count of the fish samples throughout the entire storage period （P＜0.05）. When the pressure reached 400 and 500 MPa， it effectively delayed the increase in TVB-N and pH values in the mid to late stages of storage （8-18 d） and reduced the declining rate of the total sulfhydryl content. In contrast， the changes in these indicators were not significant compared to the control group for the 100 and 200 MPa treatments. The various UHP treatments did not significantly affect the TBA value changes in the fish samples during storage（P＞0.05）. Regarding texture and color analysis， compared to the control group， the 400 and 500 MPa treatments significantly improved the hardness， elasticity，and chewiness of the fish samples throughout the storage period （P＜0.05）， but had no significant effect on cohesiveness. In terms of color， treatments of 300 MPa and above significantly improved the L* value during storage （P＜0.05）， while the a* value significantly decreased （P＜0.05）， with no significant impact on the b*value. The total color difference ΔE* value was effectively reduced. Based on comprehensive data analysis and energy consumption considerations， a treatment of 400 MPa for 5 min was considered the optimal processing condition for grouper， as it effectively reduced the total bacterial count in the fish while maintaining its quality characteristics during refrigeration.