Abstract: L. dorsi samples from pork before rigor mortis were taken and divided into two groups. The samples of one groupwere heated in water to 45, 50, 55, 60, 65, 70, 80 and 90℃ respectively. The samples of the other group were first cured in 1%,3% and 5% NaCl solution respectively and then heated to 72～75℃. All the samples were prepared into SEM and TEM specimensand the structure of the myofibrils was studied. Heating has an evident damaging effect on the myofibril structure. 40～50℃ inducedsuper-contraction of the myofibrils. At 55, 60 and 65℃, super-contraction intensified to some myofibrils while others under-went no super-contraction, together with a mild damage to the structure due to heat-induced protein denaturation. More andmore myofibrils with no super-contraction were observed at 70, 80 and 90℃, along with rising of the temperature. Coagulationof the myofilaments became more severe, which induced shortening of A-band and break of I-band, and the structure of themyofibrils was severely damaged. Higher temperatures resulted in even greater breakage. Curing with NaCl has the effect ofenhancing structural damage to the myofibrils and preventing severe contraction while heating, especially at the concentration of3%～5%.

Key words: fresh, cured, pork, heating, ultra-structure