Which method is NOT safe for preserving food?

Canning without proper sterilization methods is indeed not a safe method for preserving food. This process is crucial for preventing the growth of harmful bacteria, particularly Clostridium botulinum, which can lead to botulism, a serious foodborne illness. Proper sterilization ensures that all potential pathogens are destroyed and that the canned food is safe for consumption. If containers are not adequately sterilized, they can retain dangerous bacteria, leading to food spoilage and health risks.

In contrast, while freezing without proper sealing, refrigerating at incorrect temperatures, and air-drying in a clean environment can present risks, they may not be as immediately dangerous as improper canning. Freezing without sealing can lead to freezer burn, negatively affecting food quality but not necessarily making it unsafe. Similarly, incorrect refrigeration can allow food to enter the temperature danger zone for harmful bacterial growth, though this is typically a slower process compared to the immediate risks posed by improperly canned foods. Air-drying in a clean environment can be a safe preservation method as long as hygiene practices are followed and the food is adequately dried. Thus, the focus on proper sterilization in canning makes it uniquely critical for food safety.