Milk plays a very important role in meeting the day to day nutritional needs and requirements of a human being. It is a fulfilling product which provides the body with all the essential nutrients. In today's world there is a lot of contamination in each and every food item which is the cause of many diseases spreading in humans. Milk contains a bulk of casein molecules which play a very important role in microbiology and pharmaceuticals. The samples of milk were collected from the market surrounding places like Brahmapuram, Thiruvalluvar and Katpadi. Its nutritional quality was analysed by pH determination, Methylene Blue Dye Reduction Test Assay, and the cost of extracting casein was analysed using the principles of bioprocess economics, taking into account cost of each component used in the process. By this, the cost of casein extraction fromthe collected sampleswas easily analysed and compared with the one offered by HiMedia. The samples collection methodologies and its quality analysis will be discussed.