To explore the oxidation mechanism of wooden breast myofibrillar protein (WBMP), oxidative breast MP (OBMP) was obtained from different doses (3, 10, and 20 mmol/L) of H₂O₂ oxidized normal breast MP (NBMP). The results showed that the zeta-potential, particle size, solubility, sulfhydryl, and carbonyl contents of OBMP-3 (3 mmol/L, low-dose free radicals) and WBMP were similar. Fluorescence spectrum analysis showed that the oxidation of low-dose free radicals led to a significant increase in the surface hydrophobicity from (214.03 ± 10.03) to (393.50 ± 10.33) and tryptophan fluorescence intensity (from 185.71 to 568.32). In addition, the α-helix content of WBMP decreased significantly from (37.46 ± 1.15)% (NBMP) to (34.7 ± 2.04)%, while β-sheet and random coil contents increased significantly (P < 0.05) from (14.37 ± 0.69)% and (22.24 ± 0.78)% (NBMP) to (17.7 ± 0.87)% and (25.2 ± 1.47)% (WBMP). In summary, low-dose free radical oxidation attacks protein groups, inducing secondary and tertiary structural changes, leading to the formation of WBMP. This work will provide a theoretical basis at the molecular level for exploring the mechanism of functional degradation of WBMP.

The deterioration of wooden breast myofibrillar protein (WBMP) increases with the increase in wooden breast grades. In order to quickly and conveniently classify wooden breast to prevent waste of raw materials and unsuitable processing. Different grades of wooden breasts that exhibited mild, moderate, and severe degrees were collected, and correlation analysis was employed for the quality and WBMP functional characteristic indicators. The indicators were further classified into two components according to the principal component analysis method. Based on the correlation and variation coefficients, two main indicators were selected to represent the quality level of wooden breasts (redness (a*) and pH value (P)). The weights of the two indicators were 0.353 and 0.219 for a* and P, respectively, using the weighted coefficient method. Therefore, a formula for calculating the comprehensive evaluation score (y) of different grades of wooden breast meat was obtained: y = 0.353a* + 0.219P. Based on regression analysis, the fitting equation y = 2.407 1x + 0.0343 (R² = 0.9883) was obtained, for the comprehensive quality score (y) and sensory evaluation score (x) through regression analysis, with a fitting coefficient ˃ 0.8. This equation can accurately predict sensory evaluation scores, effectively reflect the quality differences of different grades of wooden breasts, and accurately and rapidly grade wooden breasts.