Frozen food is highly popular among consumers due to its convenience and affordability. Quick freezing refers to the use of modern freezing technology to lower the temperature of food below the freezing point in a short period of time, thereby forming small ice crystals in the food, minimizing damage to cellular tissues, and preserving the original juice and aroma of the food.

The quick freezing process is a key step that affects the quality of frozen food. The development of food quick freezing technology is towards low temperature and rapid freezing, and the form of freezing has also evolved from large disc freezing to single rapid freezing. At present, China's quick freezing equipment is mainly divided into blast type quick freezing equipment, contact type quick freezing equipment, and direct freezing equipment. Below, Xianji.com will take you to learn about the characteristics and applications of various freezing devices.

Blast type freezing device

Blast freezing technology utilizes the high-speed flow of low-temperature air to promote rapid heat transfer in food, allowing the cold air to quickly remove the heat from the food and achieve the purpose of freezing. The evaporation temperature generally used in China's blast freezing device is -35~-50 ℃, the speed of air passing through the frozen food is 2~10m/s, the temperature of the cold air flow is -30~-45 ℃, and the freezing speed is 0.5~3cm/h. Blast freezing can be divided into three types based on their structure: quick freezing machine type quick freezing device, spiral belt type quick freezing device, liquefaction quick freezing device, and airflow up and down impact type blast quick freezing device.

Quick freezing machine type quick freezing device

The quick freezing device of the quick freezing machine has a rectangular shape, and cold air circulates in the quick freezing machine. Food is frozen when passing through the quick freezing machine. According to the different ways in which food is frozen, it can be divided into hanging, basket, conveyor belt, etc. The quick freezing machine type quick freezing device has a simple structure, fast freezing speed, and can achieve continuous production, but the equipment occupies a large area. The hanging type quick freezing device is mainly used for freezing large aquatic products and poultry carcasses; The hanging basket type quick freezing device is mainly used for small and medium-sized aquatic products, fruits and vegetables, mixed foods, etc; The conveyor belt type quick freezing device is suitable for products with relatively small shapes and short freezing times, such as vegetables, aquatic products, noodles, cold food, segmented meat, etc.

Liquid state (fluidized) quick freezing device

Liquid state quick freezing device, also known as fluidized state quick freezing device, is a device that places frozen food on a mesh belt or porous groove plate with a small opening rate, causing the food particles to be blown by a high-speed vertical airflow, forming a semi suspended state (semi liquid state quick freezing) or a fully suspended state (fully liquid state quick freezing). The suspended food particles are surrounded by low-temperature airflow and quickly frozen. According to different mechanical conveying methods, it can be divided into: belt fluidized freezing device, vibration fluidized freezing device, inclined groove fluidized freezing device, etc. Liquid freezing has the advantages of fast freezing speed, no clumping of frozen products, low drying consumption, and low energy consumption. It is generally used for small-sized granular, flaky, strip-shaped or block shaped foods, such as strawberries, French fries, green beans, peas, chili peppers, chestnuts, garlic sprouts, carrots, mushrooms, and so on.

Airflow up and down impact quick freezing device

The impact type quick freezing device uses upper and lower air jets to directly impact the frozen food, clearing its thermal boundary layer and achieving rapid freezing. The impact freezing device has a much faster freezing speed and lower drying consumption compared to conventional blast freezing devices. It is mainly used for freezing thin flat foods or small volume block foods, such as fish slices, shrimp, and mixed foods.