Can I Eat Food That is a Bit Mouldy?

GAtherton's picture

I have often heard the question asked 'is it safe to eat mouldy food?'.

Opinions vary from 'scrape it off and eat, you will be fine' to 'throw anything with just a hint of mould on it into the bin'. The more informed might cut away more than the obviously mouldy section of food so as to remove all parts of the growing fungus, many might have heard that moulds produce toxins that might get into the food too - but of course we can quite safely eat some types of cheese that is sold in an obviously mouldy state eg blue cheeses, stilton. So what is safe and what isn't?

A recent article by Dr Ailsa Hocking of the Australian scientific research organisation CSIRO for the public service TV channel ABC attempts to answer many of these questions - see the following excerpt:

There are many different types of moulds that can grow on our food; the most common include Aspergillus and Penicillium, and Botrytis which you might see as a fur on your strawberries.

These moulds can produce a variety of toxins which are resistant to heat while cooking so will retain their toxicity, but these toxins are usually only harmful to us if eaten regularly.

What's safe?

If it's mouldy soft cheese, casserole leftovers or soft fruit like say berries, nectarines or peaches, it pays to know the high moisture content of these items means there is a greater chance branches of the mould have grown deeper into the food, where you won't necessarily be able to see them, Dr Hocking says.

The same rule goes for porous foods such as bread and cakes which have become mouldy. All of these foods should be binned if you spot mould on the surface.

Of course, certain domesticated moulds are deliberately introduced into our food as part of the production process — think blue cheese, for example.

While these are safe to eat, if a soft cheese that has been made with domesticated mould starts growing other types of mould, it should be discarded. (It can be tricky to tell, but Dr Hocking suggests looking out for any patches that are a different colour from the rest of the cheese.)

To eat or not to eat?

Moulds can grow in the fridge and will even survive freezing. They can also survive in salty, sugary and acidic environments.

As mould on our food is so hard to avoid, here are some general guidelines from the US Food Safety and Inspection Service on responding to the problem:

Discard all of these foods if mouldy:

  • Luncheon meat, bacon, and hot dogs.
  • Yoghurt, sour cream and soft cheese.
  • Soft fruits and vegetables
  • Bread and baked goods.
  • Peanut butter, nuts and legumes.
  • Jams and jellies,

These foods can be saved from mould:

  • Hard salami (the dry, aged type) – scrub mould from the surface.
  • Hard cheese – cut off at least 2.5 centimetres around and below the mould. Don't let the knife touch the mould and recover the cheese with fresh wrap.
  • Firm fruit and veg – small mould spots can be cut off.

So there you have it - the definitive guide to mouldy food - the full article has more details and is well worth a read, especially if you are living in Australia!