"cathepsins" - 1 õppematerjal

Liha töötlemine

7. Endogenous thiol proteinases (cathep- Without the plasticizing effect of ATP, actin sins B and L) become activated near pH 5.4. and myosin cross-link, the sarcomere short- They are redistributed (intracellularly) during ens, fibers contract, and rigor results. During aging (Spanier et al. 1990; Spanier and Miller the rigor process, muscle cells undergo both 1993). Proteolytic enzyme activity is temper- longitudinal and lateral contraction, usually ature-dependent; some (cathepsins B and L) within 24 hours. WHC decreases during the retain high activity levels even at cooking postmortem period. Rigor mortis occurs in temperatures (70°C). Pigs with defects in the beef when the pH drops to 5.9 (Honikel et al. ryanodine receptor gene (rn+) undergo exces- 1981). Factors that affect the rate of pH sive (not necessarily rapid) pH decline, decline, such as Halothane gene status of pigs