Blast Freezing: Overview, Parts, Working, Types, Advantages, Disadvantages & Applications
Whenever we keep food items like chicken or meat at normal temperature, it deteriorates quickly. The bacteria and germs start developing exponentially, making it unsafe for consumption.
You can keep them in a conventional freezer, but that will increase the shelf life of the food from almost a few weeks to hardly three months, depending on the product.
The freezing process is relatively slow and can lead to large ice crystals forming in the food. When the ice melts, it destroys the food’s cell structure and causes cell bursting, severely diminishing its texture and quality.
Blast freezing is a technique in which you can rapidly cool the food to the lowest temperature (-180C to -450C)and thus prevents the growth of microorganisms.
Rapid cooling even ensures small ice crystals in the food, which helps to maintain the texture and quality. It has wide applications, including the fishing industry, commercial kitchens, restaurants, and many more.
The article discusses more about blast freezing. So, you can keep on reading this article to learn about blast freezer, its parts, working, advantages, and applications.
What Is Blast Freezer?
The blast freezer is a special type of freezer which will rapidly freeze food at a significantly lower temperature to maintain its freshness.
Conventional freezers usually take 6 hours or more to freeze the food. But if we talk about the blast freezer, it will take hardly three to four hours to reach -18 degrees Celcius. The fastest freezing process helps maintain the quality and freshness of the frozen meat or chicken for longer.
Blast freezing is a process that involves the pushing of continuous cold air at high velocity over the meat or chicken to bring it down to the lowest temperature rapidly. The process is implemented to preserve the nutrients in food like chicken or meat for a long time.
The chicken or meat packages are stored in a blast freezer and attain -18 degrees Celsius within three to four hours. The packages are held for almost 8 hours in the blast freezer and then transferred into carton boxes. The boxes are transferred to the cold room, which will be maintained at -18 degree Celsius.
The frozen chicken or meat can remain fresh in a cold room for up to 12 months. These frozen chicken or meat are delivered to any big restaurant or commercial kitchen by a refrigerated truck which is maintained at -18 degree Celsius.
The cooling done inside the blast freezer is known as blast freezing.
Parts Of Blast Freezer
Blast freezer has various components, which are listed below.
1. Compressor
The compressor is the heart of the blast freezer. The low-pressure and temperature vapour refrigerant enters the compressor.
Its pressure and temperature increase after compression. The compressor used in the blast freezer is more powerful than a refrigerator or conventional freezer.
2. Condenser
The high-pressure and high-vapor refrigerant enters the condenser and rejects heat to the outside air. It is then condensed to liquid form at the same temperature and pressure.
3. Expansion valve
It directs the refrigerant flow into the evaporator by drastically reducing the temperature and pressure of the liquid refrigerant.
4. Evaporator
The low-pressure and low-temperature liquid refrigerant enters the evaporator tubes. The evaporator is a heat exchanger.
The refrigerant flowing inside the evaporator tubes will extract heat from the food products stored in the blast freezer and convert it into a vapor phase. The vapor refrigerant further enters the compressor, and the cycle continues repeatedly.
5. Blowers
Blowers or fans circulate high-velocity cold air throughout the blast freezer. The bowers or fans are more powerful than refrigerators or conventional freezers.
6. Themostat
It helps to control the temperature inside the blast freezer.
7. Control Panel
Control Panel allows the user to set the temperature of the blast freezer at a desired temperature.
8. Door Gasket
They are rubber seals around the door of the blast freezer, which will prevent the hot air from entering.
9. Insulation
Proper insulation inside the blast freezer will help to maintain the temperature inside the blast freezer.
10. Shelves And Racks
Shelves and rack inside the blast freezer keep various food products inside it.
11. Hinge And Handle
The hinge and handle of the blast freezer will allow the user to open and close the door properly.
12. Safety Features
Some safety features are equipped in the blast freezer, like alarm buttons.
Working Principle Of Blast Freezer
According to Government food standard agency standards, cooked food that must be frozen from 70 degrees Celsius to -18 degrees Celsius should be done within 240 minutes; otherwise, it will hamper the food quality.
The food within temperatures 68 degree Celsius to 8 degrees Celcius is considered a danger zone. The bacteria and other microorganisms quickly multiply in this temperature range and deteriorate their quality and texture.
So if you want to freeze food and store it for a more extended period without deteriorating its quality, it can be possible only through a blast freezer. The blast freezing process will continuously blow cold air on the food product so that it will cool very quickly.
We have discussed below a general overview of the working of the blast freezer.
1. Loading Of Products
The products that need to be frozen are first loaded in trays or conveyor belts, depending on the type of blast freezer you use for storing products.
2. Setting Of Temperature
Different products have different freezing temperatures to retain freshness. If we talk about chicken, it will maintain its texture and quality when frozen at -18 degrees Celsius. So you need to set the temperature according to the type of product you store inside the blast freezer.
3. Blowing Of Air
The cold air at high velocity is continuously blown over the food so that it will freeze rapidly. When the cold air circulates the food, it will draw the heat from the food stored inside the blast freezer. So here, the heat is transferred from the food product to the cold air.
The air becomes hotter and moves upward towards the evaporator. The refrigerant flowing inside the evaporator tubes will absorb the heat from the air, thus cooling the air. The cold air is blown around the food products again with the help of the blower.
The water inside will turn into ice when the food product reaches its desired freezing temperature. But because of rapid cooling small ice crystals will be formed inside the food, which will not much damage the cell structure of the product and retains its freshness.
The food product is removed from the blast freezer once it reaches the desired freezing temperature and then moves to the cold rooms.
Types Of Blast Freezers
Blast freezers are mainly of two types.
1. Batch Blast Freezer
A batch blast freezer is one of the most popular blast freezers where the food products are loaded in trays or racks and then stored inside the freezer. One advantage of this type of freezer is that you can keep various food products at once.
2. Continous Blast Freezer
The food products move on a conveyer belt through the freezing chamber in a continuous blast freezer. The method is suitable for freezing large volumes of food products simultaneously.
Advantages Of Blast Freezing
- It helps to maintain the texture, quality, color, and nutritional value of the food product stored inside it.
- Blast freezing prevents the growth of bacteria and other microorganisms from growing inside the food.
- You can store food in large batches or any leftover food inside the blast freezer. So the food doesn’t get wasted and is suitable for consumption when kept inside the blast freezer.
- Food like pasta and fruit extracts are not damaged because of the rapid cooling process.
Disadvantages Of Blast Freezing
- Blast freezers are pretty expensive compared to conventional refrigerators.
- Blast freezer consumes more energy compared to conventional refrigerator.
Applications Of Blast Freezing
- Food processing industry
- Bakeries
- Chemical industry
- Supermarkets and grocery stores
- Pharmaceuticals
Conclusion
Food products like seafood, fish, and meat get damaged when kept at normal temperatures. You can store them in a refrigerator, but they are designed for temperatures between 0 to 4 degrees Celsius.
The air blown by the fan is not at high velocity. So a refrigerator can retain the freshness of the food product only for a few days or one week.
Now if we talk about a blast freezer, it cools the food products within the shortest possible time by blowing continuous cold air at high velocity. Thus the freshness and shelf life of the food product is enhanced for many months.
We have discussed the blast freezer, its components, working, and its applications and hope the information is helpful.
