The difference between cold storage and modified atmosphere storage

What is the difference between the construction of air-conditioned storage and cold storage?

1. Sealing: Compared with the cold storage, the air tightness and water tightness of the controlled atmosphere storage are higher.

2. Materials for warehouse construction: The metal polyurethane sandwich composite board manufactured by high-pressure continuous foaming machine must be used as the thermal insulation material for the wall and roof of the modified atmosphere warehouse to ensure the sealing requirements of the warehouse under high pressure difference. Traditional cold storage can be composed of brick-concrete structure sprayed with polyurethane insulation layer or semi-automatic metal-faced polyurethane sandwich panel filled with glue and full-automatic metal-faced polyurethane sandwich panel produced by continuous foaming machine. Polyurethane sandwich composite board with metal surface manufactured by high-pressure continuous foaming machine has uniform foam and density arrangement, high closed cell rate, good strength and good flatness between boards. Similar to the yin-yang connection mode of mortise-tenon structure splicing in ancient China, it ensures the sealing performance, and perfectly solves the problem of inconsistent expansion coefficients of wall and roof materials caused by temperature difference and gas pressure difference inside and outside the warehouse, and solves the problem of cold bridge. It is an ideal material for controlled atmosphere storage and cold storage, but its price is relatively high. At present, it is basically used in controlled atmosphere storage and large-scale cold storage, while traditional brick-concrete sprayed polyurethane insulation layer and semi-automatic manual metal surface are still used in small and medium-sized cold storage.

3. The working equipment in the warehouse is different: the refrigeration equipment can only be composed of three systems, 1. Refrigeration equipment system; 2. Pipe connection system; 3. Lighting and temperature control procedures; However, the equipment required for controlled atmosphere storage mainly includes the following aspects: 1. Refrigerator, humidifier system, 2. Ethylene, carbon dioxide and oxygen detection system, 3. Carbon dioxide and ethylene remover. 4. Pipe connection system; 5. Lighting and system control procedures.

Generally speaking, the requirement of air-conditioned storage is higher than that of cold storage, which is why the cost of air-conditioned storage is higher than that of cold storage. But not all vegetables and fruits are suitable for controlled atmosphere storage.

In use, the difference between air-conditioned storage and cold storage is as follows:

1. Modified atmosphere storage time is longer, generally 0.5- 1 times longer than ordinary cold storage.

2. Compared with cold storage, the freshness and crispness of fruits and vegetables stored in modified atmosphere are better;

3. The shelf life of fruits and vegetables after controlled atmosphere storage can be extended by 2 1-28 days, and it can be extended by 3-7 days in ordinary cold storage;

4. Modified atmosphere storage is a low-oxygen environment, which can inhibit the growth of mold, pests and diseases and preserve the integrity of fruits and vegetables to the maximum extent;

5. Not all fruits and vegetables are suitable for air-conditioned cold storage, but with the cooperation of air-conditioned cold storage, most fruits and vegetables can meet the storage needs. For example, red dates and kiwis are not suitable for cold storage, but they are suitable for modified atmosphere, while berries and mushrooms such as strawberries and blueberries are neither suitable for cold storage nor modified atmosphere. Take Pleurotus nebrodensis as an example. At room temperature of 25 degrees, the color of Pleurotus nebrodensis sealed with nitrogen began to turn yellow after 5.5 days, while the color of Pleurotus nebrodensis packaged in vacuum began to turn yellow after 3 days, while the color of fresh-keeping bags with air holes began to turn yellow after 5 days, which is why most Pleurotus nebrodensis in the market are packaged in fresh-keeping bags with holes, for whatever reason.