Question

Which of the following is the time-temperature combination for UHT pasteurization?

(a) 72°C to 74°C for 15 to 20 seconds

(b) 135°C to 140°C for 2 to 4 seconds

(c) 63°C for 30 minutes

(d) 57°C to 68°C for 15 min

This question was posed to me in an interview.

This interesting question is from Heat Exchangers topic in chapter Building Blocks of Dairy Processing of Dairy Engineering

Answer 1

Correct answer is (b) 135°C to 140°C for 2 to 4 seconds

To explain: UHT Pasteurization involves heating the milk to between 135°C to 140°C for 2 to 4 seconds. The extreme heat targets Coxiella burnetii, which causes Q-fever. The heat kills all the vegetative forms of bacteria and the milk can survive for 9 months.