Question: How much time does it take for cheese to go mouldy?

Claire Bryer answered on 15 Jun 2015:

How quickly mould (fungi) grows on food depends on a few things:

-The temperature. If the food is kept warm (i.e. not in the fridge) then the mould is happy to grow. Some moulds are happier growing in the fridge however. Heating the food to very high temperatures before they package it can kill the mould before it starts to grow. This is why milk is pasteurised (heated up really hot to kill the bugs!) before it goes to the shops.

-When you opened the packet of food. Often when food is packed it is done in sterile (bug-free!) conditions and once you open the packet the normal air can get in which can introduce mould spores. The longer the packet has been open the more likely mould is to grow.

-What the food actually is! The more sugar in it the more happy fungi are to grow. In foods that are very fatty it is more difficult for fungi to grow.

Cheese takes a while (a few weeks-months) to go mouldy as it is quite hard and fatty. However you might notice that if it gets wet the water helps mould grow. This is true of soft cheeses such as dairylea, where its easier for mould to grow as there’s more water.

By the way, it’s important to know that mould is not bacteria, it is a fungus! This is a different sort of bug which can survive in harsh environments and can exist as spores. Bacteria grow on food too and can make you sick, but you usually don’t see the colonies growing on it. Meat can smell ‘off’ when bacteria have turned it bad.