When food is slaughtered or harvested, its animal or plant tissue begins to decay. Without these tissues, microorganisms, such as molds, yeasts and spoilage bacteria, eat away at foods and cause the spoiling process. Other causes of spoilage include piercing or bruising of fruits or vegetables, oxidation, pest infestation and adulteration through the addition of leftover ingredients to fresh food.
When food is harvested or slaughtered and packaged for consumption it is susceptible to the enzymes present in the cells of micro organisms. These enzymes eat away at deceased foods until blanching or cooking deactivates them.
Nuts, breads, meat, cheeses, fruits and vegetables are primary targets for mold and yeast. Mold forms a network of microscopic spores that extend into the foods and cause illness or allergic reactions if consumed. Mold and yeast cause discoloration, slime and odors when present on foods.
Other agents that accelerate the spoiling process include certain disease-causing bacteria, such as Bacillus cereus, which spoils dairy products, and Clostridium, which spoils meats and poultry.
Preventing food spoilage is essential to healthy eating. Prevention includes suitable receiving inspection practices that follow producer and manufacturer instructions, keeping food in climate-controlled settings and appropriate sanitation and personal hygiene when handling food.