Freezing, by lowering temperatures to minimal values, reduces to an absolute minimum microorganisms’ ability to reproduce and all biochemical processes in a nutrient medium. During freezing, all water in a product also turns into a solid-state.
The freezing point for the vast majority of natural foodstuffs is one degree Celsius. The exact freezing point directly depends on the physical and chemical nature of the product. As the concentration of solutes increases, the freezing point of the solution decreases.
The most advanced method of freezing today is blast freezing. This is an innovative technology that allows you to preserve the structure and chemical characteristics of your products in frozen form, just like when they are fresh.
Blast freezing will allow your business to increase profits by lowering the time necessary for freezing products by 3–10 times, and also you can reduce losses in the product mass to 0.8%. Compare this to ordinary freezing, where losses can reach 10%! You can also ensure that products look more appealing and have significantly longer shelf life. One of the key benefits of this method is the lack of any pathogenic microorganisms.
Shock freezers are recommended for all kinds of berries, fruit, vegetables, mushrooms, dumpling, fish and fish products, hamburgers, and many other semi-finished goods, shrimp and other seafood, confectionery, ready meals, and desserts.
Synonyms: shock freezer, blast freezer, blast tunnel freezer, spiral blast freezer, blast freezer equipment, blast freezer systems.
Why?
- Products can be stored long-term;
- Vitamins and nutrients are preserved;
- The physical properties of frozen objects change;
- Products can be endowed with specific organoleptic properties.
Due to all this
At temperatures below zero, water transitions to the solid-state and, as a result, all biochemical processes cease and microorganism growth stops;
Through blast freezing, products retain more of their vitamins and nutrients.
How freezer equipment is categorized:
Principle of operation |
Continuous operation |
By plant type
|
Open |
By design type |
Non-passthrough |
By type of energy used |
Devices using mechanical energy |
By operating mode |
|
By freezing medium |
Ammonia |
*prohibited in a number of countries.
How blast-freezing equipment is categorized:
Design type |
Characteristic |
|||
Placement of products |
Temperature, °C |
Performance, kg/h |
Area of application |
|
Spiral conveyor |
Multilevel conveyor |
−40 |
500–3000 |
Meat products, fish, seafood, various semi-finished goods, vegetables, berries, mushrooms |
Plate quick-freezers |
Vertical/horizontal |
−40 |
200–500 |
Meat, fish and products made with them, offal, minced meat |
Tunnel type |
Vertical/horizontal
|
−40 |
150–1000 |
Semi-finished goods, dough, baked goods and confectionary, meat and fish in small chunks, berries and mushrooms, fruit and vegetables. |
Quick-freezing chambers
|
On special trolleys |
−40 |
60–400 (depending on number of trolleys) |
Dumplings and similar products, seafood; cooling of baked-goods and confectionary products |
Fluidizing devices (“fluidized bed”) |
Fluidized-bed freezing |
−40 |
150–3000 |
Chopped or small-sized products: green peas, berries, french fries, soup mixes, and seafood like shrimp, fish, etc. |
Types of tunnel freezers.
Industrial freezers create a microclimate that ensures the complete freezing of food.
A complete set for an industrial plant consists of coolant or air coolers, and they also come with natural or forced ventilation in the ceiling area.
Industrial freezers of tunnel type with air directed transversely through the structure, consisting of air coolers located in the ceiling area in tandem with devices to guide them, usually towards a drop ceiling with openings. Cold air is supplied through special openings into the chamber containing the objects to be frozen, while warm air is circulated towards the air cooler so that it is chilled.
In tunnel freezers where the coolant system is located between rows, the main feature is the presence of four tunnels with overhead tracks, into each of which products can be placed. The coolant medium is located along the walls. Air flows with the help of a fan through the channel under the drop ceiling, through special openings into the first tunnel, after which it moves to the second, third, and fourth tunnels in turn, and finally, the air flows through the fan again and the cycle repeats.
The main advantage of a tunnel freezer is a lower percentage of loss from products.
A professional freezer is suitable for all businesses producing and processing agricultural produce and also for catering establishments.
Characteristics of the main types of freezer equipment:
|
Fluidizing devices – “fluidized bed” |
Conveyor blast freezers |
Plate freezers |
Type of product |
Fruits, vegetables, mushrooms, berries, root vegetables, peas, corn, any finely chopped vegetables. |
Sausages, meatballs, dumplings, pizza, minced meat,desserts And other semi-finished goods |
All kinds of meat, fish, shrimp, and other seafood |
Air temperature in the chamber, °C |
−30…− 35 |
30…−35 |
−35 |
End-state temperature inside the product, °C |
−18 |
10…−14 |
−18 |
Freezing time, minutes |
8…15 |
8–20 |
150 |
Air freezers operate through distribution of air along a tunnel, where heat exchange takes place due to the circulation of the air at a speed of over 3 m/s.
Conveyor freezers using air are generally used for products of relatively small size. These devices move products along on a conveyor belt and the freezing occurs as the products come in contact with a cold stream of air.
Fluidized units provide freezing on a so-called “fluidized bed”. In this way various small products like berries, green peas, corn, and small bits of seafood can be frozen.
In plate freezer plants, freezing occurs through the product coming in direct contact with frozen plates. These freezers are used for fish, various parts of poultry, cheese-curd products and minced meat.
Today several options for freezing exist:
1. Standard freezing
Freezing down to 0°C.
Freezing down to −5°C – this temperature ensures that most of the moisture crystallizes.
Final freezing down to −18°C.
2. Blast freezing produces a sudden drop in temperature inside the chamber down to −30–35°C. This method allows you to speed up the freezing process, reduce losses, and better preserve the visual appearance and taste of your products.
Tunnel blast freezers are horizontally placed refrigerator/freezer conveyors. Freezing occurs evenly. Thanks to the continuous circulation of air, fast heat-exchange and quick freezing takes place.
Spiral blast freezers feature vertically placed cylindrical chambers. Devices with this design allow you to adjust the height of the products, and as a result, higher performance can be obtained.
The above-described plants are suitable for smaller products like semi-finished goods (dumplings, vegetables, meatballs, etc.), dough and baked goods, chopped meat and fish, vegetables, fruits, and berries.
Some details of how various types of food products are processed:
As meat products undergo freezing, most of the moisture within them crystallizes, and so the product takes on certain organoleptic properties and all activity of microorganisms or enzymes ceases. Optimal freezing values: t = −30°C and an airflow speed of 9.4m/s
To ensure maximum shelf life for frozen fish, the freezing process includes a glazing operation. This protects the fish from shrinkage, oxidation, or damage to its organoleptic properties.
Approximate time for freezing various products. Average values are given. Exact times depend on the specifications of the given plant.
Type of product |
Processing time, hours |
Semi-finished goods (meatballs, dumplings, pizza) |
1–1.5 |
Fish fillets |
|
Cut vegetables (carrots, beetroot, cabbage, potatoes, etc.) and mushrooms |
|
Berries (blueberries, currants, cherries) |
|
Fruits and large berries (strawberries, peaches, plums) |
1–2 |
Baked goods |
|
Boneless meat |
2–4
|
Whole fish |
|
Pies |
|
Cakes |
|
Meat (packaged)
|
4–10 |
Chicken (chopped)
|
|
Fish in blocks
|
|
Cakes |
|
Meat (whole carcass)
|
6–30 |
Choosing the right freezer equipment will ensure that your products’ taste and physicochemical properties are preserved, that output increases, and costs are lowered, which consequently means higher profit for your business.
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