Temperature induced denaturation of myosin: Evidence of structural alterations of myosin subfragment-1

•Porcine longissimus muscle was incubated pre-rigor at 20, 30 and 40 °C.•Myofibrils from PSE-like meat had significantly higher surface hydrophobicity.•Incubation at 40 °C induced structural alterations to myosin S1 unit.•Myofibrils and chymotryptic fractions from 40 °C had lower ATPase activity.•The results relate to decreased water-binding of myosin in PSE-like meat.

Denaturation of myofibrillar proteins in porcine longissimus thoracis et lumborum muscle was investigated after pre-rigor temperature incubation at 20, 30 and 40 °C. At 24 h myofibrils were isolated and myosin was further cleaved by chymotrypsin. High temperature pre-rigor induced release of myosin S1 (subfragment-1), less (P < 0.05) Ca2+-ATPase activity and structural alterations of the region of the myosin molecule that harbors S1. Surface hydrophobicity of myofibrils from the 40 °C group increased (P < 0.001), suggesting a temperature-induced structural rearrangement exposing hydrophobic groups on the surface of myofibrils which in turn may explain the reduced water-holding of PSE meat.