The possible reasons are as follows:

　　(1)The selected Oxygen absorber quality is not stable, and the type of Oxygen absorber is not suitable for this product.

　　(2)The material of the food packaging bag does not meet the requirements. The oxygen permeability should not be too high (the composite packaging material with oxygen permeability < 20mL /㎡·24h· 25OC should be selected.)

　　(3)There may be a leak in the food package, such as KOP/CPP、NY/PE、 KNY/PE、KPET/PE、PET/AL/PE and so on. Cannot use OPP/CPP，PP or PE bag.

　　(4)Oxygen absorber has been exposed to the air for too long time and has become ineffective before use.