高压与加热协同处理对牛肌肉中蛋白酶活性的影响

在不同温度(20～60℃)和压力(0.1～600 MPa)下处理20 min,对牛肌肉中蛋白酶活性的影响进行了研究.结果显示:室温下,随着处理压力的增加,酶的活力显著下降,而压力达400 MPa及以上时,酶的活力则没有明显变化,同时在pH值为3和7.5时酶的活性几乎完全丧失.200 MPa以下的压力处理使肌肉中游离氨基...

Effects of Combined High Pressure and Thermal Treatment on Protease Activities in Beef Muscle

The effects of combined high pressure (0.1～600 MPa) and temperature (20～60 ℃) treatment for 20 min on beef protease activities were studied. The results showed that the protease activities decreased with increasing pressure up to 400 MPa at room temperature, after which there was no significant change of them. The content of free amino acid increased significantly at 200 MPa and then the increased speed decreased with the pressure increasing. 400 MPa or higher pressure treatment at room temperature resulted in the increase of tryptic digestibility of protein in beef extract. There was no significant effect on protease activities and free amino acid content in beef after pressurized at 200 MPa, 40 ℃, but the protease was almost completely inactivated at pH 7.5 and free amino acid content reduced rapidly after treated at 600 MPa, 40 ℃. Part of protease activities survived in beef muscle when heated at 60 ℃. They did not change significantly when treated at 200 MPa, 60 ℃, but the free amino acid content increased obviously. Treatment of 600 MPa at 60 ℃ resulted in the inactivation of almost all the proteases and the free amino acid content also decreased markedly. The similar changes of tryptic digestibility of protein in beef extract were found when pressure applied at 40～60 ℃. 200 MPa treatment did not cause significant changes and 600 MPa treatment induced the tryptic digestibility of protein marked increase. These results suggested that high pressure treatment combined with heating could regulate proteases activities of beef and improve its quality.