Effects of high isostatic pressure on mushrooms

The possibility of high isostatic pressure treatment as an alternative to c onventional blanching of mushrooms was investigated. An important condition for successful application is a sufficient inactivation of the browning en zyme polyphenoloxidase. The experiments showed that this enzyme is very pre ssure-resistant in mushrooms. The activity increased after pressure treatme nts at 600 MPa. Higher pressures up to 950 MPa are necessary for inactivati on. The effects on texture, colour and yield of mushrooms were evaluated at these high pressures. If fresh mushrooms are used, pressure treatment resu lts in a dark brown colour. However, if mushrooms are evacuated before pres sure treatment, the colour expressed in L, a* and b* values is comparable w ith conventionally blanched mushrooms. The stiffness of the pressurised mus hrooms is larger than that of blanched mushrooms. The yield is roughly the same for the conventional blanched mushrooms and the pressurised mushrooms. (C) 2000 Elsevier Science Ltd. All rights reserved.