Why are green beans more susceptible to botulism than tomatoes if not canned properly?

Green beans are more susceptible to botulism than tomatoes primarily because they are classified as a low-acid food. Low-acid foods have a pH level above 4.6, which creates a more favorable environment for the growth of Clostridium botulinum, the bacterium responsible for botulism. This bacterium thrives in anaerobic (oxygen-free) conditions typically found in improperly canned low-acid foods like green beans.

In contrast, tomatoes have a higher acidity due to their natural acidity, which hampers the growth of Clostridium botulinum. While certain factors can influence the safety and preservation of foods, the acidity level is a crucial factor determining the risk associated with canning. Thus, ensuring proper canning methods for low-acid foods like green beans is vital to prevent the risk of botulism.