The Importance of Pre-cooling in Cold Rooms
Pre-cooling is an important but often neglected procedure in cold storage and blast freezing operations. It helps stabilize temperature, slows down the spoilage process, and prepares products for effective cold storage or freezing. For post-harvest or processing food products, pre-cooling is the most suitable method to increase shelf life, freshness, and save energy.
Whether you're storing agricultural products or packaging for blast freezing, understanding the value of pre-cooling can make a huge difference in both safety and efficiency.
Therefore, in this blog we will discuss pre-cooling, techniques, necessary optimal temperatures and advantages, so that we can understand how products stay fresh.
What is precooling?
"Pre-cooling" is the process of removing excess heat from products immediately after harvesting, processing, or production, before placing them in a cold storage unit or blast freezer. This can be described as reducing a product's temperature to a safe temperature as quickly as possible.
In post-harvest processing, pre-cooling is beneficial for fruits and vegetables because it prevents or slows down respiration rate, water loss, and microbial accumulation. For frozen or freeze-ready foods, such as ice cream, pre-cooling is necessary to ensure the explosive freezer can function effectively without becoming saturated.
In short, the pre-cooling process can be defined as a cooling step aimed at optimizing product quality and lowering temperatures while increasing energy efficiency in the refrigerator. Even a refrigerator of the highest standards cannot deliver the desired performance without the pre-cooling process.
Pre-cooling methods
Different products require different pre-cooling methods. The choice depends on the product type, volume, water sensitivity, and required cooling rate. Below are the most commonly used pre-cooling methods.
1. Room Cooling
Room cooling is one of the simplest methods of pre-cooling. Products are placed in a cold room, and the temperature of the cooled air is gradually lowered. This method is easy to use and suitable for products that do not spoil easily.
However, room cooling is relatively slow compared to other methods. It is generally used when immediate and rapid cooling is not required, or in small quantities.
2. Hydro-cooling
Hydrocooling uses cold water to remove heat from produce. Fruits and vegetables are either submerged in cold water or sprayed with cold water.
This is an effective technique because water absorbs heat much faster than air. In hydrocooling, the hydrocooler is heavily applied to leafy vegetables, root crops, and some other fruits. However, it requires clean water management and is not suitable for water-sensitive crops.
3. Vacuum Cooling
Vacuum cooling involves creating low air pressure around the product. This causes the water to evaporate and the temperature to drop. The technique is very fast.
It is applied to leafy vegetables including lettuce and spinach. Although vacuum cooling is expensive, it ensures that vegetables are cooled quickly and evenly, reducing quality loss.
4. Ice Cooling
Ice cooling involves the direct use of crushed ice or ice slurry. As the ice melts, it absorbs the heat from the product. This process is commonly used in fish processing and vegetable storage. Ice cooling is effective but requires good drainage and cleanliness.
5. Forced Air Cooling
Forced air cooling of fruits and vegetables uses fans to draw cold air from the packaged produce. This method cools the produce much faster than room cooling.
It is preferred in commercial cold storage because it can better control the temperature and facilitates cooling. Forced air cooling is preferred for packaged products and can be done before the product is stored in cold storage or blast freezers.
In conclusion, pre-cooling efficiently reduces product temperatures immediately after harvesting, thereby extending the holding freshness of the products for a longer period.
Temperatures for Precooling Various Products
The correct precooling temperature depends on the product type. Too little or too much cooling can degrade quality. Below is a general reference table used in precooling various products:
Row
Product
Pre-cooling temperature of the product (°C)
1
Fruits
1-7
2
Vegetables
0-5
3
Cut Flowers
0-2
4
Dairy products
2-5
5
Bread and flour products
0-4
6
History
2-8
7
And
In short, pre-cooling fruits and vegetables is done at a temperature that reduces respiration without causing cooling injury. Choosing the correct temperature is critical to preserving freshness and shelf life.
The Importance of Pre-cooling in Freezing and Cold Storage
Pre-cooling is a crucial component in the auxiliary function of blast freezers and cold storage rooms. It helps to increase the shelf life and relieve stress on the equipment. The benefits of pre-cooling in blast freezers and cold storage rooms include:
1. Keeps food fresh for longer.
By eliminating early field heat, pre-cooling slows enzymatic activity and microbial growth. This helps preserve freshness, flavor, and nutritional value.
Products that are pre-cooled and stored retain their freshness and quality for a longer period than products that are not pre-cooled.
2. It preserves the product's quality, color, and texture.
Sudden temperature changes can damage the cellular structure of vegetables and fruits. This is prevented by pre-cooling to avoid a sudden temperature shock.
For frozen food products, it improves the smoothness of the ice cream and the appearance of the product.
3. The explosion prevents the freezer from being overloaded.
When hot or warm products are brought directly into the blast freezer, the appliance has to work much harder. This leads to the unit consuming more energy. Pre-cooling reduces the initial cooling load, thus ensuring efficient and proper operation of the blast freezer.
4. Helps maintain a consistent product temperature.
Pre-cooled products enter cold storage or blast freezers at a similar temperature. This leads to even cooling and prevents uneven freezing or cold spots. Uniform temperature control enhances product safety and simplifies storage management.
Keskinso daCreate your cold storage project with experts.
Designing a cold storage system with effective pre-cooling requires experience and technical expertise. Factors such as product type, cooling method, insulation, and cooling capacity must work together.
Keskinso is Turkey's.Working with a reliable company that is one of the best manufacturers of cold storage rooms and refrigerated transport ensures that pre-cooling systems are properly integrated into your project. From forced air cooling units to pre-cooling ice cream machine installations, expert guidance helps prevent costly mistakes and improve long-term performance.
A professionally designed, efficient system consumes a significant amount of energy while maintaining standards in terms of product or work quality. Be sure to check out our other blog posts for more detailed insights, tips, and information on related topics.
Frequently Asked Questions
1. What is the main purpose of pre-cooling freshly harvested vegetables?
Therefore, the primary purpose of pre-cooling harvested vegetables is to remove field heat as quickly as possible, thereby slowing down spoilage of these products.
Essentially, it extends the shelf life of vegetables by inhibiting the growth of microorganisms.
2. What are pre-storage processes?
Pre-storage processes include pre-cooling, washing, sorting, grading, and treatments using chemicals or natural processes to control diseases and pests.
These are treatments that condition products for storage under low-temperature conditions. They promote cleanliness, resistance to decay, and uniformity.
3. What are the 5 methods of protection?
Five traditional preservation methods include refrigeration, freezing, drying, canning, and fermentation.
Pre-cooling helps in cooling and freezing by preparing the material for efficient cooling and is a crucial first step in cooling and freezing processes.