Throughout the world, milk and milk products are indispensable components of the food chain. Not only do individual consumers use liquid milk for beverages and cooking, but food manufacturers use vast quantities of milk powder, concentrated milks, butter, and cream as raw materials for further processing. Effective quality assurance in the dairy industry is needed now more than ever. The microbial quality of raw milk is crucial for the production of quality dairy foods. Spoilage is a term used to describe the deterioration of a foods’ texture, colour, odour or flavour to the point where it is unappetizing or unsuitable for human consumption. Microbial spoilage of food often involves the degradation of protein, carbohydrates, and fats by the microorganisms or their enzymes. In milk, the microorganisms that are principally involved in spoilage are psychrotrophic organisms. Most psychrotrophs are destroyed by pasteurization temperatures, The book has been written keeping in mind for the graduate and post graduate level bio-sciences and interdisciplinary courses.