Food preservatives such as oxygen removal packets and oxygen absorber packets are used to prevent deterioration of foods caused by microbial growth during storage and distribution, or due to poor storage and sales conditions, inferior quality of foods, and decreased color, in order to improve the shelf life and extend the value of food. The oxygen scavenger can lower the pH value, inhibiting the growth of microorganisms, and weakening the heat resistance of microorganisms, thereby promoting the effect of heat sterilization. By adjusting the pH, the antibacterial ability of dissociated or non-dissociated molecules can also be improved.