Abstract: To investigate the effects of roasting temperature and time on the quality attributes of roasted grass carp fillets, fresh grass carp fillets were deodorized, salted and roasted in an electric oven at different temperature (180, 200, or 220 ℃) for 15 min or 200 ℃ for different periods of time (10, 15, or 20 min). The shear force, color, moisture, ash and fat contents, thiobarbituric acid reactive substances (TBARS) value, acid value, and volatile composition of roasted fish were evaluated, the physicochemical properties (secondary structure, surface hydrophobicity, and total sulfhydryl group and disulfide bond contents) of myofibrillar protein extracted from roasted fish, and sensory evaluation was also conducted. The results showed that as the roasting temperature increased or the roasting time prolonged, the shear force increased; the color parameter L* value decreased, while the a* and b* values showed an upward trend; the color became deeper; the tenderness and chroma first improved and then deteriorated; the sensory score increased first and then decreased; the moisture content had a significant declining trend (P < 0.05); the fat and ash contents decreased first and then increased; the degree of lipid oxidation increased gradually; the relative contents of aldehydes and alcohols displayed a decreasing trend; the secondary structure of myofibrillar protein changed from a stable state to an unstable state; the surface hydrophobicity index (H0) and the content of disulfide bonds increased gradually, while the content of total sulfhydryl groups decreased gradually. Compared to other roasting conditions, the roasted grass carp fillets at 200 ℃ for 15 min, having a bright golden color, tasted better and had higher moisture content and lower fat content, and the structure of myofibrillar protein from it was more complete. These results suggested that the roasting temperature and time significantly affected the physicochemical properties of protein and lipid oxidation in grass carp fillets, thereby resulting in changes in the quality attributes of roasted grass carp fillets.

Key words: grass carp; roasted; quality; lipid oxidation; protein