"Vacuum cooling is the fastest method of pre-cooling for suitable products. The temperature of leaf vegetables can generally be reduced from 30°C to 2~4°C in only 25~30 minutes. In the picture below, the temperature of Chinese cabbage dropped to 4℃ in 25 minutes by Vacuum cooling. Our large Vacuum cooler can cool multiple pallets (12 pallets or even more) at the same time. So it really helps to reduce the demand for cold storage rooms. Vacuum cooling can even take place after the vegetables have been packed, but this is only possible if the packaging is provided with enough ventilating holes to let vapor leak out easily. " This is according to Arvin Lau from Vegfor Cooling Technology Limited.
Vegfor mobile 8-pallets vacuum cooling in action
"Vacuum cooling uses the lowering pressure of the sealed chamber to rapidly turn the water content in the chamber into water vapor. Furthermore, this method rapidly absorbs large amounts of heat from the vegetables to reduce their temperature. This cooling method works best with products that easily lose water, such as lettuce, mushroom, strawberry etc. Our Vacuum cooler is equipped with a moisture system to prevent the vegetables from losing too much water, and the moisture system can make cooling more quick and efficient." 
Comparison of cooling time between room cooling and vacuum cooling
"Vacuum cooling and other cooling methods may cause the vegetables to lose some water content. In all honesty, lots of other pre-cooling methods face the same problem. However, our Vacuum cooler can solve this problem through the application of our moisture system during the cooling process. The vegetables are sprayed with mist to solve the problem of water-loss. The moisture system keeps the loss of water content to negligible levels."
Chinese cabbage being loaded into a Vacuum cooler
"Vacuum cooling is a suitable method for cooling many types of vegetables, such as lettuce, peas, and peppers. This method also helps to efficiently cool broccoli, celery, and sweet corn, mushroom etc. However, Vacuum cooling is not a suitable method for cooling products with wax-like skin or relatively thick products, such as carrots, potatoes or tomatoes."
For more information:
Arvin Lau
Vegfor Cooling Technology Limited
Company address: No. 8 South Industrial Road, Songshan Lake DG, China, 52300
E-mail: arvin.lau@vegfor.com
https://www.vegfor.com