A) 120°C for 60 minutes
B) 80°C for 30 minutes
C) 60°-70°C for 30 minutes
D) 70°C for 60 minutes
Correct Answer: C
Solution :
Pasteur (1866) showed that heating would kill any micro-organism and if the sterile substances were protected from air, no other micro-organisms would appear. Pasteurization is used to preserve milk, fruit juices, beer and wines. Milk is subjected to this treatment specially in dairy farms. In the classic pasteurization treatment of milk, the milk was exposed to a temperature of about \[{{63}^{o}}C\] for 30 minutes. Most milk pasteurization today uses higher temperatures, at-least \[{{72}^{o}}C\] but for only 15 seconds. This treatment, known as High-Temperature Short-Time (HTST) pasteurization, is applied as the milk flows continuously past a heat exchanger. In addition to killing pathogens, HTST pasteurization lowers total bacterial counts, so the milk keeps well under refrigeration. Milk can also be sterilized?something quite different from pasteurization?by Ultra-High-Temperature (UHT) treatments so that it can be stored without refrigeration. With this process, in less than 5 seconds the milk temperature rises from \[{{74}^{o}}C\] to \[{{140}^{o}}C\] and drops back to \[{{74}^{o}}C\].
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