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Quick-freezing equipment

Release time:

2024-02-01

The general trend of food quick-freezing technology is low temperature and rapid freezing, and the form of frozen products has also developed from large disk-shaped freezing to monomer rapid freezing. At present, China's quick-freezing device can be roughly divided into strong blowing continuous quick-freezing device, tunnel freezing device, contact freezing device, direct freezing device.

The general trend of food quick-freezing technology is low temperature and rapid freezing, and the form of frozen products has also developed from large disk-shaped freezing to monomer rapid freezing. At present, China's quick-freezing device can be roughly divided into strong blowing continuous quick-freezing device, tunnel freezing device, contact freezing device, direct freezing device. (1) Strong blowing continuous quick-freezing device Strong ventilation quick-freezing device adopts finned tube evaporator, the blower adopts centrifugal fan or axial flow fan with higher pressure head, and the refrigerant is forced to circulate with ammonia pump, so it has the characteristics of high heat transfer efficiency and small floor area. Generally, the speed of air passing through the frozen objects is 3~6 m/s, and the temperature is 40~30 ℃, so the quick freezing speed is 2~4 times faster than the quick freezing speed of the pipe rack type. The frozen objects can be mechanically interrupted or continuously entered, and the production capacity is large. (2) Tunnel-type freezing device The tunnel-type freezing device is equipped with an air cooler and a blower. The frozen items are installed on the trolley. When passing through the tunnel, cold air is blown to make them freeze quickly. Tunnel freezing device, because it is not restricted by the shape of food, food is transported on the hanging rail, and the labor intensity is small. Most of the devices use axial flow fans, with high wind speed and fast freezing speed (but the food dry consumption is large). The evaporator defrosting uses hot ammonia and water at the same time, so the defrosting time is short, and its characteristics are large air volume and fast freezing speed. (3) Contact-type freezing device Contact-type quick-freezing device is also called flat-plate quick-freezing device. Its working procedure is to place food between each layer of flat plates and compress the flat plates with oil. As the refrigerant in the hollow flat plates evaporates and directly contacts quick-freezing, the heat transfer coefficient is large, the quick-freezing time is short, and it can be operated at room temperature. This device can use Freon, brine, etc. as a refrigerant, but the disadvantage is that the structure is complex, can not be continuous production, and the thickness of frozen food has a certain limit. (4) Direct freezing device This method requires that the food (packaged or not packaged) is in direct contact with the non-freezing liquid, and the food is quickly cooled and frozen after heat exchange with the non-freezing liquid. Direct contact freezing method requires direct contact between food and non-frozen liquid, so there are certain restrictions on non-frozen liquid, especially when it comes into contact with unpackaged food. These restrictions include non-toxic, pure, no peculiar smell and strange gas, no foreign color and bleach, non-flammable, non-explosive, etc. In addition, the original composition and nature of the food should not be changed after the non-freezing liquid comes into contact with the food.

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Rapid freezing causes food to form tiny ice crystals

Quick freezing generally refers to the use of modern freezing technology to reduce the temperature of food to a certain temperature below its freezing point in the shortest possible time, so that all or most of the water contained in it will form reasonable with the external heat of the food. Small ice crystals minimize the liquid moisture necessary for the life activities of microorganisms in food and the biochemical changes of food nutrients, A way to maximize the preservation of the original natural quality of food.

Characteristics of frozen food

General quick-frozen food should have the following five elements (characteristics): freezing should be carried out at 30~18 ℃, and should be completed in about 20 min; The temperature is rapidly reduced to below the temperature of microbial growth activity, which is conducive to inhibiting microbial activity and enzymatic biochemical reactions. The central temperature of frozen food should reach below -18~15 ℃, water in quick-frozen food forms numerous needle-like small ice crystals with a diameter of less than 100 μm to avoid the formation of large particles of ice crystals in the intercellular space. The distribution of ice crystals is similar to that of liquid water in raw materials, causing little damage to cell tissue structure. When food is thawed, the water melted by ice crystals can be quickly absorbed by cells again without juice loss.

Quick-freezing equipment

The general trend of food quick-freezing technology is low temperature and rapid freezing, and the form of frozen products has also developed from large disk-shaped freezing to monomer rapid freezing. At present, China's quick-freezing device can be roughly divided into strong blowing continuous quick-freezing device, tunnel freezing device, contact freezing device, direct freezing device.

How to lose weight quickly with frozen foods

The volume of food is also one of the factors that affect the weight loss effect of dieters, according to researchers in the United States. Nutritious frozen foods are easy to consume and can be used as a method of controlling food volume.

At present, China's quick-freezing device can be roughly divided into strong blowing continuous quick-freezing device, tunnel freezing device, contact freezing device, direct freezing device.

Nutrition experts working in the University's Food Science Laboratory compared the two dietary regimens, with subjects using the first dietary regimen eating their own food prepared according to the "nutrition pyramid" as a guide. Subjects who adopted the second diet plan ate packaged frozen food as the main meal every day, and configured auxiliary dishes according to the "nutrition pyramid. Both diets contain 1700 calories per day and equal amounts of carbohydrates, protein, and fat. Before the start of the experiment, both groups reported an average daily intake of about 2400 calories; the subjects weighed about 97kg and had a body mass index (BMI) ranging from 26 to 42, making them overweight or obese.
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