Microorganisms can be divided into three categories according to their oxygen requirements:

　　1. Obligate aerobic bacteria, it can only grow under aerobic conditions.

　　2. Obligate anaerobe, it grows only in the absence of oxygen.

　　3. Facultative aerobic bacteria, or facultative anaerobe, can grow under either aerobic or anaerobic conditions.

　　As a whole, there are obligate aerobic bacteria and facultative aerobic bacteria, but food mildew is mainly caused by obligate aerobic bacteria. Therefore, "food deoxidizer" is used in food to remove the oxygen in food packaging containers, avoid the growth of mold and contaminate food, and effectively extend the shelf life of food.