The effects of pressure treatments with kiwi fruit protease on adult cattle semitendinosus muscle

The tenderizing effects of kiwi fruit protease on semitendinosus muscle were investigated. Adult cattle semitendinosus muscles were immersed in kiwi fruit protease (crude actinidin) at 20 °C for 15 min, and pressurized at 0–500 MPa and then heated at 80 °C for 15 min. The decreasing effects of the kiwi fruit protease-treatment with 0–500 MPa pressure on shear force and work done values were larger than those of the pressure-treated samples without kiwi fruit protease. Ultrastructures of the myofibrillar protein of the muscles treated with kiwi fruit protease showed the disorganization of the actin and myosin fillaments. The unheated and kiwi fruit protease-treated connective tissue, with pressure treatment (0–500 MPa), had little soluble α-chain collagen and after pressure treatment without kiwi fruit protease, soluble α-chain collagen was not obtained.