What is one indicator of food being infected with Listeria?

The presence of Listeria monocytogenes in food can often be indicated by its ability to grow at refrigeration temperatures. This is particularly concerning because most pathogens cannot thrive in such cool environments. Listeria is unique among foodborne pathogens as it can grow at temperatures as low as 32°F (0°C) and has been found in a variety of refrigerated foods like processed meats and dairy products. This characteristic not only allows it to proliferate in settings where other bacteria are kept at bay but also highlights the importance of proper food storage and handling to ensure safety.

The other indicators listed do not specifically relate to Listeria. A sour smell is not a definitive sign, as many foods can smell sour for reasons unrelated to Listeria contamination. The change of color to green is also not a characteristic behavior of Listeria; food spoiling can show various colors due to different bacteria or molds, but this does not point specifically to Listeria. Lastly, the creation of bubbles when food is cooked is not an indicator associated with Listeria contamination and could be due to other factors such as the natural gases released during cooking. Thus, the ability of Listeria to thrive at refrigeration temperatures is a key reason for its identification as