Abstract: This study compared the effects of vacuum frying and conventional deep-frying on the structural characteristics of myofibrillar proteins in duck drumette, and it also elucidated the mechanism by which vacuum frying retards poultry protein oxidation. The results demonstrated that the degree of protein aggregation and degradation in the vacuum-fried group was significantly lower than that in the convention-fried group (P < 0.05). Moreover, the solubility and amino acid content significantly increased by 14.93% and 12.86%, respectively (P < 0.05). Compared with the control group, vacuum and conventional frying increased protein carbonyl content by 21.4% and 164.27% and decreased sulfhydryl group content by 6.89% and 7.69%, respectively (P < 0.05). In addition, they decreased the proportion of α-helices by 6.90% and 8.97%, and elevated the proportion of β-sheet, indicating an increase in the disorder degree of the protein. Frying and irradiation resulted in the exposure of tryptophan and tyrosine residues in myofibrillar proteins, consequently leading to a decrease in ultraviolet (UV) absorbance and intrinsic fluorescence intensity, indicating alterations in the tertiary structure. Convention frying led to a rough surface with low porosity, accompanied by cracks or depressions caused by thermal stress; the structure exhibited a randomly stacked morphology. These observations suggest severe oxidative cross-linking of the protein. The vacuum-fried proteins exhibited a smoother surface with loosely packed particles in some regions and slight aggregation occurring. In conclusion, vacuum frying significantly alleviates myofibrillar protein aggregation, degradation, and oxidative damage while causing less damage to protein microstructure compared to conventional deep-frying.

Key words: vacuum frying; crispy duck drumette; myofibrillar protein; oxidation mechanism; protein structure