used packaging materials are divided into

1) Polyolefin classification: polyethylene (PE) and polypropylene (PP).

2) Vinyl polymer classification: ethylene vinyl acetate copolymer (EVA), polyvinylidene (PVC), polyvinylidene chloride copolymer (PVDC), ethylene-vinyl alcohol copolymer (EVOH),.

3) Polystyrene (PS)

4) Polyamide (PA)

5) Polyester (PET)

2 Attention should be paid to the selection of packaging materials

- The packaging box should be made of high-barrier material, and the boxed film will vary according to the characteristics of different products.

- The packaging box should have high barrier in terms of moisture permeability, oxygen permeability and light transmission;

- The common features of packaging films are anti-fogging and low light transmittance. Different products with different air permeability should choose different films with different characteristics. For example, the respiration of fruits and vegetables will affect the proportion of mixed gas, and the air permeability of the barrier film must be relied on. to maintain the balance of the gas ratio;

Storage environment:

The storage environment of modified atmosphere packaging is refrigerated. At present, the temperature of refrigerated food in supermarket refrigerated display cabinets is about 33% higher than 7°C, and about 5% is higher than 13°C. The average temperature of household refrigerators is 10 to 13°C. Obviously, the current cold chain conditions cannot meet the refrigerated temperature and condition requirements of modified atmosphere packaging or vacuum packaged refrigerated food. The recommended refrigeration temperature for many non-breathing refrigerated fresh foods (such as livestock, poultry, and fish) is 0-2 °C, and the recommended refrigeration temperature for many respiratory refrigerated fresh fruit and vegetable foods (such as apples, strawberries, mushrooms) is 0-5 °C. The ambient temperature of storage also directly affects the preservation effect of food.