What is one of the signs that food has spoiled?

The presence of an off odor or unusual texture is a clear sign that food has spoiled. Spoilage occurs when food undergoes chemical changes caused by the growth of microorganisms, oxidation, or enzyme activity, which can lead to the development of unpleasant smells and changes in texture. For instance, meat may become slimy, while fruits and vegetables might become mushy or develop visible mold. These sensory indicators are critical for assessing food safety, as consuming spoiled food can result in foodborne illness.

In contrast, shiny and fresh appearances, the use of airtight containers, and long expiration dates do not accurately indicate food safety. Fresh-looking food can still harbor pathogens, airtight containers may not prevent spoilage if the food was already contaminated, and long expiration dates do not guarantee that food remains safe to eat once opened or after certain conditions such as temperature abuse.