Abstract: Hurood was subjected to ultra-high pressure (UHP) treatments from 100 to 500?MPa for 20?min before being frozen. A directly frozen sample without UHP treatment was used as a control. The changes in the eating quality, nutritional quality, sensory quality and microstructure of hurood were investigated as a function of pressure levels, and the effects of different pressure levels on the quality characteristics and microstructure of hurood were analyzed. The results showed that UHP treatments at 400 and 500?MPa decreased the thawing time of frozen hurood by 19.46% (P < 0.05), and reduced the thawing loss rate to 3.6% compared with the control group. The water-holding capacity, and protein, fat and ash contents of hurood were maintained in the 400 and 500?MPa treatment groups. The sensory score of hurood in the control and 100?MPa treatment groups was significantly lower than that of the other groups (P < 0.05), and the microstructure of hurood in the two groups was relatively loose. Hurood treated at 400 and 500 MPa had a compact structure, good quality, and a smooth and elastic surface. In conclusion, 400 and 500 MPa UHP treatments can effectively improve the quality characteristics and microstructure of frozen hurood.

Key words: hurood; ultra-high pressure; frozen; microstructure; quality characteristics