Which of the following is a sign of food spoilage that should not be ignored?

All of the listed signs—changes in color, unusual odor, and soft texture—are indicators of food spoilage and should be taken seriously. Each of these signs typically indicates that the food may no longer be safe to consume.

Changes in color can suggest the presence of bacteria, mold, or spoilage due to chemical reactions. For example, meat may turn green or grey, indicating it is no longer fresh.

An unusual odor is another critical warning sign; foods that have spoiled often emit a foul or sour smell, which can be a result of decomposing organic matter or the growth of harmful bacteria. This is often one of the earliest indicators that something is wrong with the food.

A soft texture, particularly in fruits or vegetables, can signify that the food has begun to deteriorate. Fresh produce should typically have a firm consistency; a soft or mushy texture could indicate that the food is past its prime and may harbor harmful microorganisms.

Recognizing any of these signs of spoilage is essential for food safety, as consuming spoiled food can lead to foodborne illnesses. Thus, it's crucial to pay attention to all these signs and dispose of any food showing them to avoid health risks.