During HTST pasteurization of milk, which condition is correct according to PMO regulations?

• A. 284 °F, 4 seconds
• B. 145 °F, 30 minutes
• C. 161 °F, 1 second
• D. 161 °F, 15 seconds

Answer: (D)

HTST pasteurization is defined by a specific time–temperature combination that reliably reduces pathogens in milk. The PMO sets 161°F (72°C) held for 15 seconds as the standard HTST condition. This pairing achieves the required microbial lethality (enough to meet regulatory safety levels) while keeping the milk moving through the pasteurizer so rapid cooling can follow. The other options don’t meet HTST criteria: 284°F for 4 seconds is effectively ultra-pasteurization/sterilization, not HTST; 145°F for 30 minutes is the Low-Temperature Long-Time method, not HTST; 161°F for 1 second doesn’t provide the necessary 15-second exposure to achieve the required lethality. Therefore, 161°F for 15 seconds is the correct HTST condition per PMO.