What is white mould on gravy which has been left covered up in the fridge?

The white mold you see on gravy that's been left covered in the fridge is most likely mold. It's a common occurrence with food that's left uncovered or exposed to the air for too long.

Here's why:

* Mold spores: Mold spores are everywhere in the air, and they can land on food.

* Moisture: Gravy, being a wet and sugary substance, provides the perfect moisture for mold spores to grow.

* Temperature: The refrigerator is cool, but it's still warm enough for some types of mold to thrive.

Important: Mold can make you sick, so it's crucial to never consume food that has mold growing on it.

Here are some tips to prevent mold on gravy:

* Store properly: Store gravy in an airtight container in the refrigerator.

* Use quickly: Use gravy within a few days to reduce the risk of mold growth.

* Freezing: If you want to store gravy longer, freeze it in an airtight container.

If you're unsure whether a food is safe to eat, it's always better to err on the side of caution and throw it away.