We've all been there - you're ready to sink your teeth into an apple when your finger suddenly squishes through a small furry spot. You pause, and wonder:
Is it still okay to eat?
According to the CSIRO it could be, but then again it could potentially be very dangerous.
In 2014, the CSIRO released a report which helped consumers identify what foods are okay to eat after cutting off the mouldy bits and which foods should be thrown out. The good news - your apple might be okay if you cut the mouldy piece out. The bad news - your bread and the pesto should really be tossed.
What is mould?
Moulds are microscopic single-celled organisms and can only be seen with the naked eye when they duplicate to form a matrix, called a mycelium. Moulds are fungi, related to mushrooms and yeasts. There are several types of mould, and some moulds make and release dangerous poisons called mycotoxins into food that could, over time, make you very ill. The moulds we are most likely to find in our food are Penicillium, Aspergillus and, on fruits, Botrytis.
When ingested, inhaled or absorbed through the skin, mycotoxins may cause or contribute to a range of effects from reduced appetite and general malaise to acute illness or death in rare cases. Ongoing exposure to these toxins increases the chances of suffering from a range of health issues including kidney, liver and immune system damage, and increased risk of cancers and neurological symptoms. Worryingly, the World Health Organisation (WHO)estimates that 25% of the world’s foods may be contaminated by mycotoxins.
The problem is that the extent of the spread of mycelium is not always visible, making identifying “safe” foods difficult. In other words, you need to be very careful.
What do we know?
The CSIRO states that a good rule of thumb when judging whether or not to eat or toss mouldy food is to measure its moisture content or firmness. Foods with high moisture content can have invisible toxins growing below the surface, producing mycotoxins.
If there’s a food that goes mouldy a lot, it has to be bread. Bread most definitely takes the likely-to-get-mouldy award and unfortunately, once you can see mould on the crust, it’s likely the rest of the loaf is contaminated too. For this reason, it’s best that if your bread is mouldy you throw it straight away - don’t try to ‘save it’ by cutting off the visibly mouldy bits as the mould likely extends throughout the bread.
A thin, white coating of mould on salami gets the okay, but anything out of the ordinary and you’ll want to cut it out. In some hard salamis, mould is actually added to produce a special flavour and for hams, it’s normal for dry-cured ham to develop surface mould, and as long as you scrub it off, you should be fine.
If you see mould on the top of your leftover casserole, it’s just the tip of the iceberg. Being a high moisture food, the mould filaments are likely deep within the food, contaminating a much larger portion of the food than you might think. You should always throw out these foods if there is mould present.
Soft fruits and vegetables
Mouldy strawberries are an obvious one to leave alone, but what about an orange? A tough rind doesn’t always offer the protection you might think it does, so be wary when eating any kind of mouldy soft fruit or vegetable. Mould can be lurking within the fleshy insides.
In general, eating the mould on hard cheeses is absolutely fine. This is even true when it comes to hard cheeses such as cheddar, which don’t use mould as part of the manufacturing process. If you’re unsure, however, your best bet is to cut an inch beneath the area of mould.
Cheeses such as Roquefort, blue, Gorgonzola, Stilton, Brie and Camembert obviously couldn’t exist without mould, but still, not all mould is okay. When your cheese has wild mould growing, you don’t know what type of mould it is, so it’s best to leave it alone. Especially in cheeses such as Brie and Camembert.
Yoghurt and cream are high-moisture foods, therefore are some of the easiest foods for mould to grow throughout. A small spot of mould on top could mean harmful mycotoxins lay underneath, plus mould will make yoghurt and cream taste really bad. Best to throw these out straight away, even if they just taste bad and you can’t see any mould - just because you can’t see it doesn’t mean it’s not there.
Sodium-heavy lunch meats are at high risk of becoming mouldy, with some moulds being able to grow at a fast rate with high levels of salt. If you see mould on deli meat, always toss it.
Just like salty foods, sweet foods welcome mould and the high-moisture nature of jam means mould can quickly spread. Don’t just scrape away the layer of mould and expect the rest of the jam to be unscathed, unfortunately you’ll have to throw out the whole jar.
Firm fruits and vegetables
Tough vegetables such as carrots may be able to withstand mould from penetrating, meaning providing you remove the mould, the rest of the carrot should be okay. Trim about an inch from the mouldy area and then munch away. If in doubt, always toss.
Peanuts are among the foods likely to grow the moulds that produce the most dangerous toxins, so if you notice mould in the lid of your peanut butter, toss it away immediately. Mouldy peanuts produce aflatoxins, which can be extremely harmful.
Your best bet is to avoid mould altogether by following these top tips:
- Examine food well before you buy it. Check food in glass jars, look at the stem areas of fresh produce, and avoid bruised produce;
- When serving food, keep it covered to prevent exposure to mould spores in the air and use plastic wrap to cover foods you want to stay moist;
- Empty open cans of perishable foods into clean storage containers with a tight lid and refrigerate them promptly;
- Use leftovers within 3-4 days;
- Clean the inside of your fridge regularly with one tablespoon of baking soda dissolved in 3 cups of water. Scrub visible mould on rubber casings using three teaspoons of bleach in 3 cups of water;
- Keep dishtowels, sponges and mops clean and fresh. A musty smell means mould spores are active;
- Keep humidity level in the house below 40%.
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 medical practitioner. CBHS endeavours to provide independent and complete information, and content may include information regarding services, products and procedures not covered by CBHS Health Cover policies. For full terms, click