Is it ever ok to cut off the mouldy part of cheese and eat the rest? How about slicing off the mouldy corner of a piece of bread? The answer isn’t a straightforward yes or no. According to Dr Ailsa Hockins of CSIRO Agriculture and Food, it depends on the food.
What is mould?
Moulds are fungi and they’re related to mushrooms and yeast. They can’t make their own food like plants can. Instead they breakdown food into smaller molecules that they can digest. They play an important role in nature as they help to break down waste.
Moulds can be found in almost any environment at any time of the year, but they especially like warm and humid conditions.
Mould is a microscopic single-celled organism that only becomes visible to humans when they start growing on food and water. When food and water are around, these single cells multiply and join together to form a matrix. This matrix is the furry green and white growth you see on bread, cheese and other foods. During this process, toxins are also released into the food and they can extend beyond the visible matrix, or the ‘mouldy part’. These toxins are known as mycotoxins and they can be dangerous.
What happens if we eat mouldy food?
According to the World Health Organisation, the adverse effects of mycotoxins from mould range from acute poisoning to long-term effects like immune deficiency and even cancer.
For example, patulin is the mycotoxin that is commonly found in rotting apples and if you ingest Patulin, the effects can include vomiting, gastrointestinal disturbances and nausea.
Other types of moulds can cause allergic reactions and respiratory problems. In most healthy individuals, our immune systems can deal with small amounts of these toxins without causing us harm. The danger is knowing how much you have consumed.
What’s safe to eat?
If you see mould on foods such as hard cheeses, salami and hard vegetables like carrots and cabbage, you can still eat them if you remove the mouldy part.
It’s a good idea to not only cut off the mouldy part but to also cut off at least one inch around and below the mould spot. You should also keep the knife out of the actual mould spot so it doesn’t contaminate other foods.
What’s not safe to eat?
If you see mould on foods with high moisture content such as casseroles, cooked grains and pastas, soft fruits, vegetables, sauces and soft cheeses, you should throw them out.
If you see mould on porous foods such as bread, cakes and pastries, you should also throw them out as they could be holding dangerous mycotoxins.
How can you reduce your risk?
Keeping your kitchen clean
Cleanliness is vital to reduce the spread of moulds. Mould spores from affected food can build up in your refrigerator, dishcloths, and other cleaning utensils.
The United States Department of Agriculture suggests the following ways you can minimise the growth of moulds:
- you should clean inside of your refrigerator every few months with one tablespoon of baking soda dissolved in a litre of water. You should then rinse it with water and dry. You should also scrub any visible mould on rubber casings using three teaspoons of bleach in a litre of water.
- you should also keep dishcloths, towels, sponges and mops clean and fresh. A musty smell means they’re spreading mould around.
- if possible, you should also keep the humidity level in the house below 40%.
Protecting your food from mould
The United States Department of Agriculture recommend the following ways you can protect your food from mould:
- when serving food, keep it covered as much as possible to prevent exposure to mould spores in the air.
- you should use plastic wrap to cover foods that you want to stay moist.
- empty open cans of perishable foods into clean storage containers and refrigerate them as soon as possible.
- don’t leave any perishables out of the refrigerator for more than two hours.
- use any refrigerated leftovers within three to four days so mould doesn’t have a chance to grow. If you know you’re not going to eat them, freeze them for longer storage or throw them out if they can’t be frozen
The World Health Organisation recommends the following tips to reduce your risk of ingesting mycotoxins from mould in food.
You should always buy grains and nuts as fresh as possible.
You should be particularly careful with the following foods and discard them if you see any signs of mould, discolouration or shriveling:
- wholegrains like corn sorghum, wheat, and rice
- dried figs
- nuts such as pistachio, peanuts, almonds, walnuts, coconuts, Brazil nuts and hazelnuts
Eating a varied diet
- By choosing to eat a diverse and healthy diet, it not only helps to reduce your exposure to mycotoxins, but also improves your overall nutrition.
Where to get more information
You can find out more about moulds on foods at the United States Department of Agriculture website or CSIRO.
All information contained in this article is intended for general information purposes only. The information provided should not be relied upon as medical advice and does not supersede or replace a consultation with a suitably qualified healthcare professional.