Contact type quick freezing device
The contact type quick freezing device places food between layers of plates, and then compresses the plates. Due to the evaporation of refrigerant in the hollow plate, it directly contacts the quick freezing. This device can use salt water or other refrigerants. The contact type quick freezing device has advantages such as high heat transfer coefficient, short quick freezing time, ability to operate at room temperature, small footprint, convenient installation and operation, and easy mobility. However, its structure is complex and cannot be used for continuous production, and there are certain limitations on the thickness of frozen food. The contact type quick freezing device is suitable for batch freezing of fish mince, meat, fruit puree, shellfish and other foods, and can be used on ships, etc.
Direct freezing device
A direct freezing device is a device that directly contacts food with low-temperature refrigerant for heat exchange, allowing food to quickly cool and freeze. The commonly used refrigerants include liquid nitrogen, liquid carbon dioxide, salt water, propylene glycol, etc. According to the contact method, the direct freezing device can be divided into spray type, immersion type, or a combination of two methods. The direct freezing device has the advantages of fast freezing speed and low food dry consumption, but it has the disadvantages of difficult refrigerant recovery, high loss, and high cost. And there are certain restrictions on refrigerants, especially when in contact with unpackaged food, refrigerants must be pure, free from odors and strange gases, free from foreign colors and bleaches, and not flammable or explosive.