Science

Student Science: What type of mould is growing in your house?

Gair Rhydd has a look into the different types of mould growing in your student house

As students, I’m sure we encounter mould in our day to day lives far more than the average person. There’s the cheese you’d forgotten about at the back of your fridge, the bread that went off far quicker than you’d expect, the apples that are way fluffier than they’re supposed to be. All the photos you see on this page are ones I took in my own house. Shameful, isn’t it?

There are different types of mould, all of which just love the dampness of your home. All of them are fungi, with spores that spread it through the air, water or via insects. The spores give mould the colour you see, while roots anchor it to your food, walls or shoes. Invisible bacteria may also be growing alongside the mould, as they thrive in the same conditions.

Several types of mould can be found in the house: Aspergillus, Cladosporium, Ulocladium, Alternaria, Botrytis, Busarium, Geotrichum, Monilia, Penicillium… I could go on but it wouldn’t be much help. Each type of mould can be found in differing colours and can be harmful or not, depending on what strain it is. You’d have to send samples off for lab testing to find out what kind of mould you’re dealing with, so the best thing to do would be to just get rid of it as soon as you find it.

You’ll find mould in any place where conditions allow. Ask around and I’m sure you’ll find someone who has experienced the problem of having mould in or on their shoes. I recently found a pair of black suede shoes gone white with mould – the fungus just loved the damp state I left them in, and were able to cling to the soft suede material. Not ideal.

The biggest question that you can’t deny you have asked yourself at some point: is this mouldy food safe to eat? Some people go by the colour of the mould, but there are both harmful and non-harmful kinds in each colour group. What you should go by is the type of food. Mould loves damp conditions and so the more moist food is, the less safe it is to eat.

While yogurt, milk, sauces and condiments are the most likely food to grow mouldy, eating them is a big mistake. It may seem like a good idea to just scrape the white fluff off your pesto and continue using it, but surface mould may be just the tip of the iceberg. Filaments can be buried deep within the food although invisible to the naked eye.

Leftover food, casseroles and cooked pasta all have a similar problem. They contain a relatively high moisture content so once mould appears, it’s best just to throw it out as the problem will have spread further than you realise.

There is some good news amongst all of this. With hard cheese such as cheddar it’s okay to cut the mould off leaving a margin of about half an inch. When you are cutting it do not touch the mould with your knife and rewrap it in a fresh covering to stop it from going mouldy again. The same goes for hard fruit and vegetables such as carrots, as it’s hard for the fungus to penetrate the dense structure. Cut around the mould with a margin of half an inch to one inch and you should be fine.

Bread is one of the main perpetrators of mould in the kitchen. If only one slice out of as entire load has gone mouldy it may be okay to throw just that one slice and the slices next to it away.

The most important thing to realise is that mould does not just ‘appear’. If you touch the mould on your bread and then touch your other clean food, you risk cross-contamination. Likewise if you leave mould to grow in your house and on your food, the spores will infect the air and could affect your health. Certain types of mould have been known to contain allergens, irritants, and in some cases, toxins that may trigger adverse reactions in humans. Long-term exposure to mould may cause or worsen conditions such as asthma, hay fever, or other allergies.

Living with mould can be a right pain, but there are special products you can buy to get rid of it. There’s ‘mould and mildew’ spays for the bathroom and anti-mould paint for the walls, designed to kill mould spores and roots to stop them from regrowing. Try not to let things get too fluffy and all should be fine!

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