In the process of high temperature sterilization, our products sometimes encounter problems with expansion tanks or drum lids. The reason of these problems is mainly caused by the following situations:

The first is the physical expansion of the can, mainly because the can does not shrink well after sterilization, and it is rapidly cooled, the internal pressure much higher than the external pressure and forming an outwardly convex shape;

The second is the chemical expansion tank. If the acidity of the food in the tank is too high, the inner wall of the tank will corrode and hydrogen gas will be generated, and the gas will accumulate to generate internal pressure, making the shape of the tank protrude.

The third is bacterial expansion tank, which is the most common cause of expansion tank, which is caused by food spoilage due to the growth and reproduction of microorganisms. Most of the common spoilage bacteria belong to obligate anaerobic thermophilic bacillus, anaerobic mesophilic bacillus, botulinum, obligate anaerobic mesophilic bacillus, micrococcus and lactobacillus, etc., these are mainly because of the sterilization process caused by the unreasonable.

From the above points, the canned food in the physical expansion tank can still be eaten as usual, and the content has not deteriorated. However, ordinary consumers cannot correctly judge whether it is physical, chemical or biological. Therefore, as long as the tank is inflated, do not use it, it may cause certain damage to the health.