What are common signs that food may be spoiled?

The common signs that food may be spoiled include off odors, discoloration, and mold growth. These indicators are critical for determining the freshness and safety of food. Off odors suggest that chemical changes or bacterial activity may have occurred, indicating spoilage. Discoloration can be a sign that the food has begun to deteriorate, often due to the breakdown of enzymes or the growth of harmful microorganisms. Mold growth is a visible sign of spoilage and contamination, as it indicates the presence of fungi which can be harmful if ingested.

In contrast, bright colors and pleasant smells typically signify fresh food, while firm texture and cold temperature point to proper storage conditions. Intact packaging with no air inside generally indicates that the food is sealed properly and may be safe, but these factors alone do not confirm freshness.