Pasteurization of milk is achieved by boiling at-

Ans. is 'a' i.e., 65deg C for 30 min Pasteurization o Pasteurization is done to destroy (the pathogens that may be present in milk, while causing minimal change in the composition, flavor and nutritive value. o Pasteurization kills nearly 90% of the bacteria in milk, including the more heat resistant - Tubercle bacilli - Q fever organisms o It does not kill the thermoduric bacteria. o It does not kill bacterial spores. There are 3 widely used methods for pasteurization : a. Holder method: Milk kept at 63-66,}C for 30 minutes is rapidly cooled to 5degC. b.HTST method: 'High-temperature short time' method (Flash method) o Heated to 72degC for 15 sec. and then rapidly cooled to 4degC o This is now the most widely used method. c.UHT method: o Ultra-high temperature method. o Rapidly heated in two stages to 125degC for few seconds, o The second stage is being under pressure. o It is then rapidly cooled.