home Food Fermentation: The Hidden Microbial World Behind Some of Your Favourite Foods

Fermentation: The Hidden Microbial World Behind Some of Your Favourite Foods

By Nathan Carey, Food Editor

In recent years there has been a surge in popularity of fermented foods such as sourdough breads, artisan beers, kefirs and kimchi. There is no doubt you’ve walked past some new hip bakery selling nothing but sourdough treats and kombucha to wash them down. For thousands of years humans have used fermentation as a way of preserving foods like meats and dairy. While the process of fermentation has been around for a while, advancing technology and scientific evidence has helped create these delicious treats in an easier and more controlled manner. Fermented foods are defined as foods that have been created using controlled amounts of microbes that enzymatically change the structure and taste of the original food. There have long been murmurings of miracle effects from these microbial concoctions, and while first believed to be nothing more than fiction, the scientifically backed evidence of the benefits of consuming fermented foods on the regular is growing. 

Many of the health benefits associated with fermented foods are linked to the compounds present in them and how they interact with our bodies, specifically our gut microbiota. Almost 80% of the microbes present in our bodies hang out in our gut. This staggering fact is driving scientific research in the area of gut health and how it can impact our overall wellbeing. Fermented foods have been shown to contain metabolites, such as short chain fatty acids, that can interact with certain gut hormones like ghrelin. Ghrelin has been coined by many as the ‘hunger hormone’, but in just the last 5 years research has shown that ghrelin may play a much larger role in our overall health. Ghrelin receptors located in our stomach can have their rate of secretion altered by short chain fatty acids, hence decreasing the amount of ghrelin in circulation. Therefore drinking a glass of kombucha or munching on a slice of sourdough bread, both of which contain small amounts of short chain fatty acids, may alter many of the processes in our bodies. Besides this, fermented foods also contain a myriad of probiotics that have been proven to improve gut health. You may be asking yourself, how is our gut so important in so many regulatory systems in our bodies? This question can be answered by investigating the gut-brain axis. This axis is a bi-directional communication system between our gastrointestinal tract and our central nervous system – both the brain and gut can send complex signals and instructions to each other that influence our mood and behaviours. One way in which both your gut and brain can communicate with each other is through the vagus nerve. This nerve may sound familiar as it is the 10th in a series of 12 pairs of nerves known as the ‘cranial nerves’. This nerve serves as the longest nerve in the autonomic nervous system, responsible for involuntary physiological processes such as our blood pressure and heart rate. When changes in the makeup of our gut microbiota start to occur, the vagus nerve communicates with our brain and alters neurotransmitter release. Neurotransmitters are chemical messengers (usually amino acids) released from neurons that tell our brain networks how to function. In short, changes in our gut microbiome can change signalling pathways in our brains. 

All this sounds great right? While the rational is all there, extensive studies on the actual changes caused by fermented foods have yet to be completed. Hopefully over the next couple of years, more research can be completed to add credence to the health benefits of these funky foods. Aside from their host of effects, fermented foods also just taste great! While more complex processes like kombucha need to be explained in a much longer piece of writing, quick lacto-fermented vegetables and kimchi are a great way to start your fermented food journey at home. These processes are fairly straightforward and yield amazing results.


Lacto-Fermented Pickles

When people think about pickles, the long green cucumbers in a jar most often come to mind. However most firm vegetables can also be pickled and taste amazing when they are. The process of lacto-fermentation makes use of the lactic acid bacteria that is already present on most vegetables. When oxygen is taken away and the vegetables are placed in an environment where the microbes can grow (lots of salt) the bacteria can convert the natural sugars in the vegetables into lactic acid. This is what gives fermented and pickled foods their sharp acidic bite. Lactic acid acts as a preservative and allows the pickles to stay safe for consumption for up to 3 months. To start you will need to create a brine solution of water and salt. The ratio can vary but I usually choose a 2% brine solution, in this case 15 grams of salt for 750ml of water. 

  • Add chopped vegetables of choice to a glass vessel, mason jars are a great option. Keep the pieces a uniform size so they ferment at a similar rate. 
  • Pour over the brine solution until the vegetables are completely submerged. Leave a small bit of head room for any carbonation that may occur. 
  • Fit a lid loosely onto the vessel and place in a bowl or on a plate to catch any spills. Leave the vegetables at room temperature for 24 hours after which you can lift the lid off and look for the tell-tale fermentation signs. 
  • There will be some small bubbles on the surface and the vegetables should smell slightly sour. If these signs are not present you can place the lid back on and allow them to sit at room temperature for a further 24 hours. 
  • Once you see the signs, the lid can be tightened and the vessel can be placed into the fridge to slowly continue its fermentation process for 2 weeks. 
  • The pickles are good for up to three months and are a great addition to any salad or as a topping on meat dishes. 



This staple of Korean cuisine is probably top of the list when people talk about fermented foods. Traditionally it’s made from napa cabbage that has been mixed with chillies, garlic, ginger and spring onions. It’s a great side dish and can also be added to salads or broths for ramen and other noodle dishes. This recipe uses gochujang which is a fermented Korean chilli paste. I’ve chosen this as it is relatively easy to find in your local Asian grocery store. While you’re there pick up a head of napa cabbage (sometimes called Chinese leaves).


  • 1 head of napa cabbage 
  • Salt 
  • 5 spring onions 
  • 1 carrot 
  • 2 garlic cloves 
  • Thumb sized piece of ginger 
  • 60ml fish sauce 
  • 100g gochujang 



  • Cut the cabbage down the middle to halve it, then down the middle again to quarter it. Slice the quarters into 1 inch pieces and place into a bowl. Sprinkle salt all over the cabbage (you will need more than you think here). Squeeze and toss the cabbage until the salt is incorporated. Allow to sit for 1 hour.
  • Chop carrot and spring onions into bite sized pieces. Add garlic, ginger, fish sauce and gochujang into a food processor and blitz until combined. 
  • After one hour, thoroughly rinse cabbage and ring out any excess liquid. Add to a large bowl with the chopped vegetables and chili paste. Thoroughly mix all ingredients together until all the vegetables are completely coated. 
  • Add the mixture to a glass vessel like a mason jar and push it down using a muddler or spoon. It is important to make sure the kimchi is very packed into the jar to prevent oxygen getting trapped in the jar. 
  • Once pushed into the jar add a loose fitting lid and place the jar somewhere safe for about one week. You can check in on day 2 and 4 to ensure that the cabbage is fermenting, look for the same signs as previously discussed. 
  • After one week the lid can be tightened and the jar can be placed into the fridge. 

As always if you make any of the recipes featured in the Express, we would love to see them! You can post a picture on Instagram or Twitter with the hashtag #ExpressCooks.