The vacuum pump works faster than the cooling compressor. When pre-cooling vegetables and lettuce, the vacuum process saves time, money and energy – often with vacuum pumps from BUSCH.
Vegetables and lettuce are delicate products. After the harvest, they quickly lose their freshness and are prone to rot. The proven countermeasure is cooling. The healthy greens are cooled during transport and storage, like other fresh foodstuffs.
Short processing time for large quantities
During the harvest in the summer and early fall, crops usually have a temperature of 20 degrees Celsius or more. These temperatures can also be a lot higher if the sun is shining strongly. If an entire field with broccoli, pepper or iceberg lettuce is harvested, large quantities of this produce need to be cooled to two or three degrees Celsius. This would block a large cooling chamber for several hours using conventional cooling.
The process is significantly faster with vacuum cooling: It only takes 10 to 25 minutes to bring a truckload of fresh produce to the desired temperature. Afterwards, they can be taken away in a refrigerated truck or temporarily stored in the cooling chamber without a long cooling phase.
Vacuum lowers the boiling point
The vacuum method uses the low boiling point of water under vacuum. The vegetables are placed onto pallets in a large vacuum chamber. The chamber is closed, and the air is evacuated using vacuum pumps. Under vacuum, the water in and on the crop begins to evaporate. The resulting water vapor is extracted with the air.
This quickly extracts heat from the produce. Moisture also evaporates from the inside of the plant parts. But the moisture loss from this method is less than when conventional cooling is used in the cooling chamber. In addition, delicate vegetables and lettuce with particularly large leaf surfaces can be sprayed with water before the process begins. This reduces moisture loss while boosting the cooling effect. BUSCH offers a wide range of vacuum pumps in different sizes that are ideally suited for this application. The process also saves energy when compared to conventional cooling processes.
Fast cooling for fresh greens
Vacuum cooling preserves the quality of crops
What do flowers have to do with vacuum cooling?
For cut flowers, immediate cooling after the harvest is almost more important than it is for vegetables and lettuce. Even the slightest discoloration and rotten flecks make it practically impossible to sell ornamental plants – if their heads are drooping, they are tossed directly to the compost pile. The length of time the cooling process takes also plays a critical role in the quality of these very delicate products. In addition, flower trade logistics chains are always on particularly tight schedules – so every hour counts. This industry considers the vacuum process the method of choice for fast pre-cooling to achieve the best results with the highest efficiency.
For cut flowers, immediate cooling after the harvest is almost more important than it is for vegetables and lettuce. Even the slightest discoloration and rotten flecks make it practically impossible to sell ornamental plants – if their heads are drooping, they are tossed directly to the compost pile. The length of time the cooling process takes also plays a critical role in the quality of these very delicate products. In addition, flower trade logistics chains are always on particularly tight schedules – so every hour counts. This industry considers the vacuum process the method of choice for fast pre-cooling to achieve the best results with the highest efficiency.