In hot regions, the sun helps to dry out the perishable food like fruits, vegetables, fish etc. In cold regions, nature helps to keep perishable food for a longer time in good condition like meat and fish. Salting and natural fermentation also helped man for the availability of few important foods. Heat and cold are the principal agents to store the food. Many of these techniques of food preservation are based on a scientific basis, with the result that today food preservation industry is perhaps the largest industry in the world. Preservative means a substance, which when added to food is capable of inhibiting, retarding or arresting the process of fermentation, acidification or other decomposition of food by the growth of microbes.