Mold is something commonly associated with rotting food and there's nothing quite as stomach churning as picking up a piece of fruit to discover it's half covered with a green, furry growth. It seems to get on everything. That half finished cup of coffee left on your desk over the weekend, the stale loaf of bread a few days past its sell by date or a slab of cheese opened a week ago. They've all been attacked by mold. But where did it come from and why does mold develop on food?


What is Mold?

Mold is a type of microscopic fungi which, when greatly magnified, looks similar to a cluster of tall, spindly mushrooms. They are like tiny plants with a stalk and root system. What we see as a layer of mold covering food are the tops of the stalks which are called spores.

There are several thousand different molds in existence, so many that the actual number is unknown.  This is why all molds don't have the same color. For instance, you may notice the mold on bread can sometimes have a blackish tinge, whereas the mold covering fruit looks green. It's the millions of spores that give mold its particular color.

How Mold Grows on Food

Mold spores are transported from one place to another mostly through air currents. Once airborne, the spores can float around then fall again in much the same way as pollen from a flower. Once the spores land on a surface, they seek out water and nutrients to feed from. And coupled with the right conditions they begin to take root and start burrowing and spreading then reproducing even more spores. Some develop in as little as 24 hours while others can take weeks.

Generally molds thrive in a warm, moist environment, although some are robust enough to survive well in cold temperatures. For instance, many foods packaged in bottles, jars or tins, stipulate they must be refrigerated after opening and used within a certain time period. Once opened, the food has been exposed to any floating spores and is now at risk of developing mold. By storing it in the fridge, the developing mold will be slowed but not stopped.

Is Mold Harmful?

Mold spores are present in the air we breathe and for most of us they pose little cause for concern. However, mold that has developed on our food mustn't be eaten. Once the spores have landed on a food source and taken root, they begin producing poisonous toxins called mycotoxins and these toxins can make us extremely ill if consumed.

In certain cases mold isn’t harmful because it is grown in a controlled environment. Distinctive blue veined cheeses such as Roquefort and Stilton or those with white surface molds such as Brie and Camembert have specially cultured molds introduced during their production. These molds add to their flavor and are perfectly safe to eat.

Mold can develop on almost any type of food as long as it has access to a source of nutrients, air and moisture. Therefore, by leaving food exposed to the air for any period of time immediately puts it at risk of the floating spores which can then quickly take root and develop into a covering of mold. So by following storage guidelines and regularly checking any food that's stored in the open air, you should be able to keep your food safe and free from developing harmful and toxic molds.