Mushroom blanching is a short heat treatment applied before freezing, canning or drying to inactivate enzymes, stabilise colour and reduce volume, preserving quality through subsequent processing.
In trade practice
Processors control time and temperature precisely to achieve full enzyme inactivation without softening texture excessively. Water or steam blanching are both used, with steam generally causing less nutrient leaching. QA teams verify inactivation using a peroxidase test, and blanching parameters are recorded as part of HACCP documentation. Under-blanching is a common fault that leads to colour degradation during frozen storage.
In a specification
A specification typically states blanching method, target core temperature and maximum hold time, with peroxidase-negative status required as a pass criterion.