Although the fruiting body of the brown beech mushroom (Bunashimeji, Hypsizygus marmoreus) is known to contain several proteases, the proteolytic effects of these proteases on myofibrillar proteins have not previously been examined. We prepared a crude protease fraction from the fruiting body of the brown beech mushroom and examined its proteolytic effects on pork myofibrillar proteins.
The crude protease fraction hydrolyzed the myosin heavy chain in the pH range of 4.0-10.0, whereas actin, the other major myofibrillar protein, was unsusceptible to the enzyme. Treating pork tissue with the crude protease fraction at 25℃ for 1 h caused a substantial morphological change in the surface area of the meat. These results suggest the possibility of the protease preparation being suitable as a meat tenderizer. The protease fraction prepared from the brown beech mushroom was more susceptible to being heated than that from the maitake mushroom (Grifola frondosa) fruiting body, suggesting its advantage in preventing oversoftening of the meat by rapid inactivation of the enzyme from heating during cooking.
