<P> Bacteria can be responsible for the spoilage of food . When bacteria breaks down the food, acids and other waste products are created in the process . While the bacteria itself may or may not be harmful, the waste products may be unpleasant to taste or may even be harmful to one's health . </P> <P> Yeasts can be responsible for the decomposition of food with a high sugar content . The same effect is useful in the production of various types of food and beverages, such as bread, yogurt, cider, and alcoholic beverages . </P> <P> Signs of food spoilage may include an appearance different from the food in its fresh form, such as a change in color, a change in texture, an unpleasant odor, or an undesirable taste . The item may become softer than normal . If mold occurs, it is often visible externally on the item . </P> <P> Spoilage bacteria do not normally cause "food poisoning"; typically, the microorganisms that cause foodborne illnesses are odorless and flavourless, and otherwise undetectable outside the lab "." </P>

Visual signs of spoilage for fruits and vegetables