What are the requirements of the gas in the package?
For example, some fruits, vegetables, air conditioning packaging, as well as cold meat also have the atmosphere of the tune (20% carbon dioxide, 80% oxygen), low temperature, preservation for about a week, to maintain fresh meat color, prevent browning!
The higher requirements are modified packaging: oxygen, nitrogen and carbon dioxide are used to fill the package in proportion to the product - respiration - use, to extend the shelf life of the product, and outside
Some of the most common baked foods, moon cakes, fried foods, potato chips, which are filled with nitrogen, are required to be food grade, high purity, minimum requirement is no harmful gas impurities!
