Microorganisms: making our food delicious!

By Becca Smithers

Lots of our food and drink are produced with the help of microorganisms! These bacteria and fungi break down sugars in food and drink and convert them to acids, gases, or alcohols. This process is called fermentation.

Fermented Favourites

Do you enjoy the odd chocolate bar? Maybe a cheese sandwich? A lovely yoghurt? How about a cup of coffee, beer, or wine? These foods are all made through the process of fermentation. Different species of bacteria and fungi are involved in fermentation depending on what sugars are being broken down.

Bread, beer, and cheese are all products of fermentation.

Bread, beer, and cheese are all products of fermentation.

Lactic acid bacteria break down sugars in milk to give us yoghurt and cheese. Yeast, which is a fungus, is used to make bread and many alcoholic drinks. Cocoa is fermented by lactic acid and acetic acid bacteria, breaking down the pulp surrounding the beans, so that we can access the cocoa bean inside to make delicious chocolate.

Fermentation is a traditional process of food preservation. Before we had fridges we needed to find a way to keep food for a long time, and fermentation was a great way to do this. Pickling vegetables and drying meats allow bacteria to begin breaking down the food but in a way that accents the flavour and stops the food rotting.

Yeast cells under a microscope. Each dash on the scale is one micrometre. 10 micrometres = 0.1 millimetres. CC-BY-SA Bob Blaylock

Yeast cells under a microscope. Each dash on the scale is one micrometre. 10 micrometres = 0.01 millimetres. CC-BY-SA Bob Blaylock

Beneficial Bacteria

Bacteria tend to get a bad reputation. At the first sign of being ill many people will rush off to get antibiotics, but this is hugely damaging to the good bacteria in our bodies. 9 out of every 10 cells in your body does not belong to you, it belongs to the microbes that live in and on your body. These microbes are not harmful to us, in fact they help us to digest food and stay healthy in many ways.

Fermentation of food and drink products uses bacteria that are not harmful to us. The good bacteria are used to preserve the food and colonise the food enough so that the bad bacteria causing rot and decay do not have a chance to take control! Eating fermented foods can help keep a balanced gut microbiome, which means that you have more good bacteria in your gut than bad. Fermented foods are sometimes marketed as “probiotics”, meaning good bacteria!

How does fermentation happen?

C6H12O6 → 2 C2H5OH + 2 CO2

            Glucose   →    ethanol   +   carbon dioxide

The above is a basic equation for fermentation. A sugar breaks down into an alcohol and a gas. Depending on the species of bacteria, different gases can be produced such as hydrogen. Fermentation needs cells to in order for the process to work. Bacteria and fungi are perfect as they feed on glucose and sugar molecules and get rid of the alcohols, gases, and acids.

There are a couple of stages in the process of fermenting glucose. The first stage is a process called glycolysis, which literally means glucose degradation. The glucose molecules are broken down into smaller molecules called pyruvate. If there is no oxygen present, which means the conditions are anaerobic, the pyruvate molecules will ferment in cells, releasing carbon dioxide and producing alcohol.

Pyruvate can also be fermented to lactic acid, which is what happens in the human body when muscles are working hard but do not have enough oxygen supply. Glucose is broken down into pyruvate for energy for the muscles, but the lack of oxygen means our cells ferment pyruvate into lactic acid. A build up of lactic acid in muscles results in cramps and muscle fatigue. This is why athletes do high intensity activity for short periods of time, to make sure their muscles do not get too tired or damaged from long periods of anaerobic exercise.

Fermentation is a natural process and has been part of human culture for a very long time. Next time you enjoy a fermented food or drink, don’t forget about the marvellous microorganisms that helped make it!

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