The most obvious reason is to kill microorganisms such as pathogens, toxins, spoilage bacteria, and destruction of food enzymes so that the product could be deposited longer without deterioration. But heat sterilization is closely monitored to preserve food quality and nutrition as much as possible.
Canned sterilization has gained rather controversial ideas from medical and health researchers and microbial researchers.
Generally speaking, canned food does not require to achieve sterile levels as long as pathogens and toxins cease to exist. In the present, the determination of canned sterilization is not determined by empirical test, but rather with a scientific method which is well-calculated with accurate theoretical value.