Rheological Properties of Salt-Soluble Protein from White and Red Skeletal Muscles

The rheological behavior of chicken pectoralis (white) and thigh (red) salt-soluble protein (SSP) was investigated. In 0.6 M NaCl, both pectoralis and thigh muscle SSP exhibited pseudoplastic flow with a maximum shear stress at pH 6.0. Shear stress and viscosity of pectoralis SSP were greater than those of thigh SSP at identical shear rates (0.23—46.1 s^-1), pH (5.75—8.0), and protein concentrations (1-10 mg/mL). However, relaxation time for SSP samples following shear appeared to be independent of muscle type. Shear stress steadily reduced, albeit showing a small peak around 13-19 °C, with increasing temperature from 5 to 37 °C for pectoralis and from 5 to 44 °C for thigh and then rose abruptly at higher temperatures due to gel formation. The results indicate that white and red SSP are similar in rheological patterns but differ in magnitude, which may be attributed to the various isoforms of myofibrillar proteins.