We are aware that food safety is an important issue for the conscientious cook. Flavor and appearance take a far second place to safety when we are preparing our meals. The concept of "spoilage" is an important one to understand to prevent foodborne diseases.

Spoilage

This is a change in odor, taste and texture in foods caused by bacteria that reproduce in food that has not been stored in optimal conditions. Be aware that although spoilage may be a good indication that food could be dangerous, it does not necessarily mean so.

Bacteria that cause spoilage are not dangerous, but the fact that they have reproduced may indicate the presence of Pathogenic bacteria due to inadequate storage conditions. A food could be spoiled and be perfectly safe to eat while it could be dangerous to eat and not show any evident problem.

For food safety reasons the refrigerator should stay at about 41 °F (5 °C) or less to avoid the growth of bacteria.

Freezing food stops bacterial growth but it will not kill existing bacteria. If the food was already contaminated before freezing it has the same potential to cause diseases as a food contaminated and left outside the freezer.


Source:
Food Safety and inspection service
Gateway to Government Food Safety Information