Abstract: The effects of different degrees of woodiness (mild, moderate and severe) on the physicochemical properties and structure of chicken breast myosin were investigated. The results showed that the particle size and turbidity of myosin in wooden chicken breast muscle were increased compared with those in normal chicken breast muscle, reaching the highest values in severely wooden chicken breast muscle. The net negative charge loss and sulfhydryl group content decreased significantly with increasing degree of woodiness (P < 0.05), and the surface hydrophobicity increased significantly, reaching 747.57 ± 23.36 at a severe level of woodiness. Moreover, the occurrence of woodiness adversely affected the secondary structure stability of myosin, resulting in progressive conversion of α-helix to β-turn and random coil. The maximum endogenous fluorescence intensity of severely wooden myosin was higher than that of normal myosin (860.6 versus 505.1), indicating substantial exposure of tryptophan residues to the hydrophobic environment. In addition, the microscopic network structure of wooden chicken breast myosin was more disordered, and a large area of voids was formed when woodiness reached a severe level. Therefore, woodiness significantly affected the physicochemical properties of chicken breast myosin and higher degree of woodiness caused more serious structural deterioration.

Key words: wooden chicken breast; myosin; physicochemical properties; molecular structure