Certain types of bacteria produce spores in response to environmental stresses. In general, bacterial spores are dormant forms of cells that are much more resistant to heat, dehydration, freezing, and irradiation than the vegetative forms of the cells. In food processing, these increased resistances are of concern for food spoilage and food safety reasons. Spores are associated in nature with soil, dust, and water. Some spore-forming organisms such as Clostridium perfringens are also associated with the intestinal tracts of humans and animals. Because spores have a high resistance to desiccation, it is not surprising that spores are detected in many foods containing dehydrated ingredients, such as starches, vegetables, grains, and spices.