Mushroom freezing is the preservation of blanched or raw mushrooms at minus 18 degrees Celsius or below, most commonly in IQF or block format, for supply to food manufacturers and retail packers.
In trade practice
Most commercially frozen mushrooms are blanched before freezing to inactivate enzymes that cause discolouration and texture loss; blanch time and temperature are validated per variety and cut size. IQF tunnels freeze individual pieces rapidly, while block freezing is used for lower-cost industrial supply. Buyers specify glaze percentage, as excess glaze inflates net weight and distorts yield calculations. Microbiological testing on finished product is standard, with results required before shipment release.
In a specification
A frozen mushroom specification states the format (IQF or block), maximum glaze percentage, storage temperature, and whether blanching is required, along with microbiological and defect limits.