Modified atmosphere packaging is a relatively new technology in current food packaging, including deoxygenated packaging and inflatable packaging. There are various methods for gas regulation, which vary depending on equipment conditions and gas concentration requirements. In general, they can be divided into these types: natural oxygen reduction, ammonia filling for oxygen reduction, gas replacement with the most suitable concentration indicator, vacuum gas blending, and gas regulation packaging.

(1) Deoxygenated packaging

Mechanism D: Deoxygenated packaging refers to the use of continuous ammonia filling and vacuum pumping to remove oxygen from the packaging container before sealing the packaging. 2. Characteristics: Generally, after this method of treatment, there will still be 2% -3% oxygen residue, so it is often necessary to add deoxidizer small packaging or deoxidizer thin sheets to the packaging bag. Commonly used deoxidizers include reduced iron powder, ferrous salts, platinum film, glucose oxidase, ascorbic acid, oleic acid, etc,

3 Application: This method is not suitable for packaging fresh fruits and vegetables due to the basic lack of oxygen in the packaging container,

(2) Inflatable packaging

① Mechanism: Inflatable packaging is a sealed packaging process in which one or several gases are filled into the packaging container, and commonly used filling gases include oxygen, ammonia, and carbon dioxide Feature: It is very important to choose the appropriate gas and gas composition for the packaging object. For fresh fruits and vegetables, it is necessary to not only reduce oxygen and suppress respiratory intensity, but also consider their tolerance to low oxygen and high carbon dioxide. It is generally believed that the composition of 022% -5% and CO23% -8% in the gas is suitable for most fruits and vegetables. At the same time, fresh fruit and vegetable products in inflatable packaging must be stored at appropriate low temperatures to prevent overheating from causing excessive respiration and oxygen deficiency, leading to respiratory disorders,

3 applications: For fresh meat and meat products, using 60% CO2 and 40% N2 inflatable packaging has a better effect. Low oxygen can prevent the formation of oxygenated hemoglobin, which is beneficial for maintaining the bright red color of fresh meat. At the same time, it can also prevent the growth of aerobic microorganisms and the oxidation and deterioration of unsaturated fatty acids in meat products. It has been verified that ham packaged with 60% CO2 and 40% N2 inflatable packaging has better oil leakage, degree of oxidation and deterioration, and storage time than pure vacuum packaging. But some studies also suggest that trace amounts of oxygen should be retained to inhibit the proliferation of anaerobic microorganisms.