Tunnel freezing is an industrial freezing method in which product travels on a belt or trays through an insulated tunnel where high-velocity refrigerated air rapidly reduces product temperature, and it underpins most IQF production lines for berries, sliced fruit and vegetables.
In trade practice
In a continuous tunnel freezer, product enters at ambient or chilled temperature and exits fully frozen, with airflow and belt speed calibrated to achieve the required core temperature within the tunnel length. Operators monitor air temperature, belt speed and product load to prevent under-freezing at peak throughput. Maintenance teams check fan performance and insulation integrity regularly, as any drop in airflow velocity increases the risk of slow freezing and product clumping. Buyers auditing suppliers should confirm that tunnel parameters are logged and reviewed against specification limits.
In a specification
A supply agreement may reference tunnel freezing as the required freezing method and specify that time-temperature records demonstrating rapid pull-down are retained and available on request.