banner ad

HF Guide to Fermenting Food

Print Friendly, PDF & Email

Seren Hollins looks at fermentation as a way to preserve and enhance food – an ancient form of storing produce as well as using Kefir as an ingredient. Kefir is reputed to be very beneficial in restoring important gut microbes and is generally good for all-round health.

Throughout history, mankind has used fermentation to preserve food and improve its flavour. Today, we also know that fermentation offers nutritional benefits, but it’s easy to dismiss fermented foods for fear they might taste dreadful, and it’s worth bearing in mind that cheese, beer, wine and bread are all fermented foods, so it’s not quite so alien to the modern diet after all.

Fermentation preserves food, with live-culture yeasts and bacteria producing alcohol, lactic acid and acetic acid – all ‘biopreservatives’ that retain nutrients and prevent spoilage. Vegetables, fruit, milk, fish and meat are highly perishable, and to extend their storage our ancestors used a variety of preserving techniques, including wild fermentation. Fermentation not only preserves nutrients, it also breaks them down into more digestible forms. Soya beans are very protein-rich but largely indigestible without fermentation, which breaks down their complex protein structure into digestible amino acids to give us the culinary delights of miso, tempeh and tamari (soy sauce).

I cannot talk about fermentation without mentioning the new nutrients this process can create, as they hold wonderful health benefits. Some live cultures have been shown to function as antioxidants, scavenging cancer precursors known as ‘free radicals’ from the cells of your body. Eating raw fermented foods is undoubtedly a good way of supplying your digestive tract with living cultures essential for breaking down foods and assimilating nutrients.

As fermented foods and drinks are quite literally alive with flavour and nutrition, I decided to begin a fermentation journey of experimentation and discovery, starting by ordering some milk kefir grains. The morning they arrived I ripped open the parcel to reveal a small sealed package of milky grains – my live milk kefir grains.  So, with a sterilised coffee jar and 250ml of organic milk we began our milk kefir journey.

  • Kefir grains are the most traditional, economical and nutrient-dense way to make kefir.
  • Kefir grains are reusable, and with proper care can be used indefinitely. They are certainly the best value in the long term, but you need to look after them: culturing for 12–48 hours and then transferring the grains to fresh milk to make a new batch.
  • Powdered kefir starter culture is created in a laboratory and designed for single use, but can be utilised a few times before weakening – ideal if you are not able to maintain it on a daily basis, or want to make kefir just occasionally.
  • If you use real kefir grains and want to take a break, put the grains in a jar with milk (as you would to make kefir), then cover with a tight-fitting lid and refrigerate. The cold slows the fermentation process and the grains become semi-dormant, but you must change the milk every week or two.
  • I ordered my grains from Happy Kombucha (, who use organic milk to grow their cultures. They cost £12.50, but this is good value considering the daily yield.
  • Once established you can divide the culture and pass on to a friend.
  • Apparently you can freeze it although I’ve not tried this, yet.



1           Put your grains into a clean, glass 1-litre jar.

2           Add 250ml of full-fat goat’s/cow’s milk and leave the milk kefir grains to settle and feed.

3           Cover the jar with a doubled-over piece of muslin and secure it using a rubber band or string.

4           Place in a warm (but not hot) position out of direct sunlight and leave for 24 hours or until it begins to separate.

5           When the kefir has finished working, strain the grains (using a plastic strainer) from the kefir milk, but keep them safe – they are reusable.

6           The first batch of kefir milk is not as thick as consequent batches will be. I was advised to discard the first batch, as the grains are ‘adjusting’ to their new home, and it is usual for a first batch to taste yeasty.



1           When the kefir begins to separate, give it a stir with a non-metallic spoon.

2           Separate your milk kefir grains from your kefir drink by emptying the contents of the jar into a plastic strainer over a bowl.

3           The milk kefir drink will strain through and the grains can then be reused.

4           Wash the jar (or use a fresh jar) and place the grains and any residue they are in into the jar, then top up with a pint of fresh, organic milk and replace the muslin top.

5           Drink the kefir milk, and then the process begins again.

  • Less is more – letting cultures ferment for longer will not yield better results. Kefir is best when it’s done fermenting at 24 hours, or when sour and tart like natural yoghurt. Letting it go for 48 hours or longer diminishes the probiotics, as the bacteria run out of food and start to die.
  • No metals please! Use only plastic spoons, spatulas and sieves.
  • Don’t wash your kefir grains in water – it washes off their protective coating of bacteria and yeasts, and they will be harmed. They can survive, but it diminishes the good bacteria and yeasts, and they won’t be as strong.

Kefir milk is a little like natural yoghurt and is used in much the same way. It can be consumed naturally, mixed with muesli or even made into ice cream. My girls enjoy it with soft fruits blitzed for a few moments in the blender for a probiotic smoothie. I’m partial to a kefir smoothie myself too, although my kefir bread recipe takes some beating in terms of taste.


With the kefir fermenting in the background, it was time to embrace the world of lacto-fermented vegetables, which at first sounds a bit frightening. Before I embraced kimchi, sauerkraut and other fermented foods, I had vague notions of lacto-fermentation involving milk, bacteria, and specimen jars mysteriously bubbling away in dark cupboards. Thankfully, I discovered that the world of fermented food is far from scary, and very tasty.

Lacto-fermentation doesn’t necessarily have anything to do with dairy products – ‘lacto’ simply refers to lactic acid. All fruits and vegetables have beneficial bacteria such as lactobacillus on the surface, and in an anaerobic (oxygen-free) environment, these bacteria convert sugars into lactic acid, which inhibits harmful bacteria, acts as a preservative and gives fermented foods their characteristic tangy, sour flavour.

There is no need for special fermenting vessels or fancy equipment – if your vegetables are submerged in brine they are in an anaerobic environment and perfectly safe. If you want to weight them down you can, but I find a large cabbage leaf tucked over the top of the vegetables and down the insides of the jar is effective at keeping them submerged.

If you start fermenting vegetables you will be in good company – Captain Cook was recognised by the Royal Society for having conquered scurvy among his crew by sailing with large quantities of citrus fruit and sauerkraut. On his second circumnavigation in the 1770s, sixty barrels of sauerkraut lasted twenty-seven months, and not a single crew member developed scurvy, which had previously killed huge numbers on long trips.

  • 1 head of cabbage
  • 1 tbsp caraway seeds
  • 2 tbsp salt

Clean absolutely everything – when fermenting anything, it’s best to give the good, beneficial bacteria every chance of succeeding by starting off with as clean an environment as possible.


1           Discard any wilting or damaged outer leaves of the cabbage – reserve one good, intact, large outer leaf for use later – then cut the cabbage into very thin ribbons; I use a mandoline slicer, but a sharp knife works fine.

2           Combine the cabbage, salt and caraway seeds in a large ceramic bowl and begin working the salt into the cabbage by massaging and squeezing it with your hands. At first it may not seem like enough salt, but gradually the cabbage begins to release its juices and looks a bit like coleslaw. Patience is necessary, as the process takes 5–10 minutes.

3           Take handfuls of cabbage and pack them tightly into a sterilised jar. Tamp it down well with your fist and pour any liquid released by the cabbage while you were massaging it into the jar.

4           Over the next 24 hours, press down on the cabbage every so often with a spoon. As it releases more liquid it becomes more limp and compact, and the liquid rises over the top of the cabbage.

5           As soon as the cabbage has released enough liquid to cover it, place the larger outer leaf of the cabbage reserved earlier over the surface of the sliced cabbage. This helps keep it submerged in its own liquid.

6           If, after 24 hours, the liquid has not risen above the cabbage, dissolve 1 teaspoon of salt in ¼ pint of water and add enough liquid to the jar to submerge the cabbage.

7           The cabbage needs to ferment for 3–10 days, away from direct sunlight and at a cool room temperature. A small batch of sauerkraut ferments quicker than a large batch – closer to 3 days than 10 days. Keep an eye on it and press it down if it starts floating above the liquid.

8           Taste it after 3 days, and when it tastes good to you, refrigerate it. It’s all about taste, so the duration of the fermentation will depend on what your taste buds require.


  • Don’t worry if you see bubbles coming through the cabbage while fermenting, or foam on top, or white scum – these are all signs of a healthy fermentation process. Scum can be skimmed off during fermentation or before refrigerating. However, check there is no mould forming, as this is something we do not want to be consuming.
  • As sauerkraut is a fermented food it will keep for at least 2 months in the fridge. As long as it still tastes and smells good to eat, it will be fine.
  • Store your sauerkraut at a cool room temperature; at high temperatures it can become unappetisingly mushy, or it can go off.

Fermented carrots are great for livening up a simple salad sandwich, and are delicious with hummus. I use different varieties of carrots to get a multicoloured, pretty looking jar, but any fresh carrots will do.

  • 680g carrots, trimmed and quartered
  • A 2.5cm piece of root ginger, peeled and thinly sliced
  • 2 tbsp salt
  • 1 cabbage leaf (optional)
  • 850ml warm water

1           Combine the salt and water in a measuring jug, then stir until the salt dissolves.

2           Put the ginger in the bottom of a sterilised 1.5-litre preserving jar, then place the carrots in the jar in an upright position.

3           Pour the brine over the carrots, leaving at least 2.5cm of headspace at the top of the jar. If necessary, add more water to cover the vegetables. (Optionally, tuck a cabbage leaf over the vegetables to hold them under the brine.)

4           Cover the jar tightly and let it stand at room temperature. Open the jar once a day to taste the pickles and release any gases produced during fermentation. Any mould or scum can be skimmed off.


Use only salt free from iodine and/or anti-caking agents, which can inhibit fermentation – rock salt contains neither.

















Posted in: Making Preserves

Post a Comment

Pin It on Pinterest

Share This