Unless food is preserved in some manner, it will spoil. The microorganisms that can cause food spoilage include molds, yeasts and bacteria. They grow well in moist conditions and can easily contaminate foods. Molds appear as fuzz on foods. Molds can be destroyed by temperatures between 140 degrees F and 190 degrees F. Yeasts also grow in high or low acid environments.
Yeasts can cause foods to ferment.
They are destroyed, however, at temperatures between 140 degrees F and 180 degrees F. Bacteria grow and multiply rapidly on food. Each type of bacteria varies as to the temperatures at which it can grow. They may grow at cold, warm or hot temperatures. Some bacteria need oxygen to grow, others don't. Most bacteria grow best on low acid foods, such as vegetables or meats.