How can post-pasteurization contamination with Listeria occur?

• A. Only during pasteurization.
• B. Through environmental contamination, contaminated equipment, or packaging lines after pasteurization, while Listeria can grow at refrigeration temperatures.
• C. Listeria cannot survive after pasteurization under any conditions.
• D. Listeria growth is prevented by sealing packaging.

Answer: (B)

Post-pasteurization contamination occurs when the product is exposed to contaminants after it has been pasteurized. Pasteurization reduces microbial load but isn’t a guarantee of sterility, so any Listeria that gets onto surfaces, equipment, or packaging lines after pasteurization can enter the product. Listeria monocytogenes is particularly problematic because it can survive and even grow at refrigeration temperatures, meaning contamination in the plant can translate to growth during storage in the cold chain. It can persist in biofilms on equipment and around packaging lines, making sanitation and environmental monitoring essential to prevent this route of contamination. The other ideas don’t fit because pasteurization isn’t the only time contamination can occur, Listeria can survive post-pasteurization conditions, and simply sealing packaging doesn’t guarantee safety if contamination happens after sealing or if growth can occur in the cold.