WHAT CAUSES SPOILAGE?

FROM CREATURES TO CLIMATE, THESE ARE THE CULPRITS IN FOOD’S EXPIRATION

ENZYMES

Enzymes are proteins that speed up some of foods’ chemical reactions, and one of their purposes is to ripen fruits and vegetables. Enzymes don’t just work to make food perfect for your palate, though, and they will continue to turn fruit from unripe, to ripe, to over-ripe. They are the reason your fruit continues to the disgustingly soft, squishy stage. When you bite into fruit, oxygen reaches the broken plant tissue. In apples, enzymes work quickly with this oxygen to produce compounds with a brown colour.

ANIMALS

Although we have designated some items as ‘human food’, they are not exclusively sought after by us. Other animals share the same tastes, and so in order to keep some fresh for ourselves, we need to store food away from animals like rodents, insects and parasites. When food is damaged by these creatures, it makes the deterioration process quicker, as well as increasing the likelihood of spreading disease.

AIR

21 per cent of air consists of oxygen, which can attack the fats in food. In fact, oxidation is the main cause of spoilage in fatty foods. When the fat oxidises, it forms smaller short-chain carbon compounds. It’s these compounds which produce a strong smell and unappealing taste.

TEMPERATURE

Different foods have their own optimum temperature for storage, which will prolong their shelf life. Usually warm temperatures are avoided during storage, as this can speed up the rate of enzyme activity, while freezing temperatures can cause some foods to break, like the protective shell surrounding eggs. Microorganisms usually thrive at room temperature, making fridge or freezer storage the best option for fresh foods. Between 10 and 37 degrees Celsius is the most common range in which food is handled. Just a ten degree increase in temperature can double the rate of chemical reactions within a food item.

MICROORGANISMS

When bacteria and fungi grow in food, they can cause a change in colour, texture and smell. Many foods are not just desirable to us humans, but can also provide energy to these single-celled organisms. The microbial world is a diverse one. Some food growths create a green, mouldy appearance, clearly indicating the presence of fungi, while others can grow to harmful levels with zero visibility. It’s important to remember that not all microbes are bad to consume, and some even hold health benefits.

LIGHT

Food and drink are often covered in light-proof packaging to prevent photodegradation, the alteration of products due to light exposure. Some reactions that occur within foods require light for them to take place. Light can cause damage to the chlorophyll of fruit and vegetables. These are the cells that give some plants their colour. Over time this reaction can cause discolouration in foods.

PHYSICAL DAMAGE

When bringing shopping into the house, you might take extra care with the softer fruits and food unprotected by packaging. Some fruits and vegetables have their own protective layer, but when this is damaged, threats such as microorganisms, air and small creatures can get into the food, increasing the rate of spoilage.