Thermally induced gelation of chicken myosin isoforms

Thermally induced gelation of one white muscle myosin (pectoralis) and two red muscle myosins (iliotibialis and gastrocnemius) from chicken was investigated using small-strain oscillatory theology. In dynamic heating conditions (25-75 degrees C at 1 degrees C/min), pectoralis myosin gelled at an onset temperature 5 degrees C lower and developed a greater storage modulus (G') than red muscle myosins. Gel curing at 75 degrees C for 3 h after dynamic heating increased in G' values, but the relative magnitudes in G' remained the same for all myosins. The isoform-associated rheological differences at 75 degrees C were lost when gels were evaluated at 25 degrees C. This was true for G' values determined over a 0.16 a interval and G (shear modulus) values after 1 h of imposed strain. Differences were also noted with isothermic gelation (45, 50, or 55 degrees C). The pectoralis myosin gelled at 45 degrees C, but the two red muscle myosins did not. The G' values for pectoralis and iliotibialis myosins gels were not significantly different at 50 degrees C; however, they were significantly greater than values for gastrocnemius myosin gels. There was no significant differences among the G' values for gels at 55 degrees C. These results indicate that the dynamics of gelation and temperature sensitivity of intramatrix forces are different among myosin isoforms. Therefore, any relative evaluation of rheological properties must be under temperature conditions that reflect those typical of the meat product application.