Freezing rate is the speed at which product temperature passes through the zone of maximum ice crystallisation, directly determining crystal size, cell damage and the texture and drip loss of the thawed product.
In trade practice
Buyers of whole berries and soft fruit specify IQF processes precisely because the high freezing rate produces small ice crystals that preserve cell integrity. Slow freezing, associated with inadequate tunnel capacity or overloaded belts, results in large crystals, mushy texture and high drip loss on thawing. Suppliers demonstrate adequate freezing rate through freezing curve records and drip loss test results on finished product. Drip loss is commonly measured at intake as a proxy indicator of the freezing rate achieved during production.
In a specification
Specifications for IQF fruit typically state a maximum drip loss percentage after controlled thawing as an indirect measure of freezing rate adequacy, rather than specifying the rate itself.