Final answer:
Commercially canned goods are made safe by using heat to kill botulism spores, a practice that has greatly reduced the incidence of botulism, once a common foodborne illness before improved canning procedures.
Step-by-step explanation:
Commercially canned goods are typically safe because they use heat to kill botulism spores. Clostridium botulinum is the causative agent of botulism. A pressure canner is recommended for home canning because endospores of C. botulinum can survive temperatures above the boiling point of water. To preserve food safety, low- and medium-acid foods are heated to 121 °C for a minimum of 2.52 minutes in commercial sterilization processes, which reduces the population of endospores to a safe level. Killing C. botulinum endospores requires a minimum temperature of 116 °C, well above the boiling point of water. This temperature can be reached in a pressure canner, which is necessary for processing low-acid foods. The heat during the canning process effectively eliminates the risk for botulism, which was more common before better sterilization and canning procedures were established.