Effects of high isostatic pressure on mushrooms

The possibility of high isostatic pressure treatment as an alternative to conventional blanching of mushrooms was investigated. An important condition for successful application is a sufficient inactivation of the browning enzyme polyphenoloxidase. The experiments showed that this enzyme is very pressure-resistant in mushrooms. The activity increased after pressure treatments at 600 MPa. Higher pressures up to 950 MPa are necessary for inactivation. The effects on texture, colour and yield of mushrooms were evaluated at these high pressures. If fresh mushrooms are used, pressure treatment results in a dark brown colour. However, if mushrooms are evacuated before pressure treatment, the colour expressed in L, a* and b* values is comparable with conventionally blanched mushrooms. The stiffness of the pressurised mushrooms 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.