This blog post on fermentation is an excerpt from the Octopus Alchemy handbook on fermentation – you can access the full text here.
Fermentation is the transformation of food by various bacteria, fungi and the enzymes and acids that they produce. The power of fermentation has been harnessed throughout the ages to preserve foods. The other amazing offshoot being that fermentation also creates vibrant, living food that can be used as a powerful healing modality too, whilst reconnecting us with the ecology at large.
Before there were cans, refrigerators and freezers, fermentation was the main way people avoided spoiling food. The earliest forms of fermentation took place in pits, lined with leaves and packed full of all kinds of food: vegetables, meat, fish, grains, tubers and fruit. The practice of fermentation is pre-history. It is difficult to ascertain how and where it began. Louis Pasteur is given credit for identifying and pioneering the science of microbiology in 1857. Before that, early cultures were experimenting with and enjoying the benefits of different ferments, without the intricate knowledge we have today.
The health benefits of fermented foods:
Ultimately, fermenting foods makes them more nutritious. In some cases, there arise entirely new and unique nutrients during the fermentation process. Fermentation is essentially a form of pre-digestion, it breaks food down into simpler, safer and more manageable forms that the body can handle. Long protein chains, fats and carbohydrates difficult for the body to absorb are broken down by the resident lactic acid bacteria: carbohydrates are converted into lactic acid and proteins are broken down into amino acids. Minerals are thus better absorbed. Eating fermented foods also encourages healthy acid production in the stomach, which in turn encourages better performance of the pancreas and liver and therefore secretion of essential digestive enzymes and bile. Further, most of the lactic acid ferments are acidic, but have a significant alkalizing effect in the body.
Fermentation also degrades toxic or undesirable substances in food – two prominent examples are cyanide in cassava and phytic acid, a particularly insidious anti-nutrient found in most grains (inhibiting the uptake of various essential minerals such as calcium, zinc, magnesium and iron). Oxalic acid, prevalent in leafy green vegetables also hinders the absorption of nutrients and is rendered partly innocuous through fermentation.
The Vitamin C content is also preserved in fermented vegetables, not to mention creating a whole host of B vitamins (folic acid, niacin, thiamin, riboflavin and biotin). The process of fermentation also brings forth an abundance of unique micronutrients: Sauerkraut for example contains micronutrients suspected to fight cancer, including isothiocyanates and sulforaphane. Not to mention the master detoxifying glutathione found in the liver. Slimy, strong smelly Natto for instance, a ferment of soy-beans from Japan, produces a unique beneficial enzyme called nattokinase of which the medical applications abound. But even more! Superoxide Dismutase, GTF chromium, phospholipids, digestive enzymes and beta 1,3 glucans – in short, fermented foods are small powerhouses of nutrition which promote a cascade of healing effects in the body that we’re just beginning to chart out and understand.
“Wild fermentation” is the technique of using and manipulating the bacteria already present in foods, to preserve and transform food into more readily digestible and therapeutic forms. Most fermentation processes rely on the complementary relationship and interaction between different forms of bacteria, yeasts and sometimes molds to bring about the desired effect / product. The most important and desirable bacteria in our ferments are the lactobacillaceae, which have the ability to produce lactic acid from carbohydrates. Other important bacteria, especially in the fermentation of fruits and vegetables, are the acetic acid producing acetobacter species.
Away from wild fermentation, other forms of fermentation may use a started culture, such as from whey, a product of raw milk. The practice of fermentation is widespread, and exists in every culture. It is one of the most important methods to process food. Today, no less than a third of what is eaten in the world is made via a process of fermentation. Many of these foods and beverages are extremely popular, although few people will consciously realize that fermentation processes are involved. But coffee, chocolate, vanilla, bread, cheese, wine, mean and beer, yoghurt, ketchup and most other condiments; vinegar, soy sauce, miso, certain teas, corned beef and pastrami, ham and salami are all dependent on fermentation.
Here are some examples of different fermented foods:
Products of lactic acid fermentation include: Sauerkraut, olives, pickled vegetables, kimchi, Russian kefir, Indian dahi, yoghurt, spice from the Middle East, Western cheeses and sausages, Egyptian laban and kishk, Greek and Turkish trahana, Mexican pozole, sourdough bread, Indian idle, dohkla and Khaman, Ethiopian teffinjera and Thai fish sauce.
Products of alkaline fermentation are less known. In alkaline-fermented foods, “the protein of the raw materials is broken down into amino acids and peptides; ammonia is released during the fermentation, raising the pH of the final products and giving the food a strong ammoniacal smell.
Most alkaline fermentations are achieved spontaneously by mixed bacteria cultures, principally dominated by Bacillus subtilis. Although in some cases, pure cultures can be used.
Products of alkaline fermentation include: African iru and ogiri, dawadawa, pidan and kenima; Japanese natto, Thai thua nao and pidan.
Wild fermentation is a very simple technique. Using good quality vegetables (preferably organic), salt and water, it doesn’t take an expert to produce the incredibly tasty and healing foods discussed above. By submerging the chopped vegetables in salty brine, you create an environment in which fungi and other oxygen-dependent organisms cannot survive. The saline environment also ensures that the lactic acid bacteria are given priority and develop. The bacteria that spur on the fermentation process are already present in the vegetables, lying dormant until the conditions are appropriate: moist, oxygen-free, saline and with easy access to nutrients in the plant material that have been sufficiently prepared and bruised.
The bacteria responsible for fermentation are wild strains of lactic acid bacteria that are already present on raw vegetables, including Leuconostoc mesenteroides, Lactobacillus brevis and Lactobacillus plantarum. These are halophilic (salt loving) anaerobic organisms, so they thrive in the oxygen-free saline environment that the fermenter has created. They immediately begin to feed on the sugars in the vegetables or fruit, and multiply. Emitting large amounts of lactic acid, which poisons and inhibits the growth of their competitors. L. mesenteroides flourish under all kinds of circumstances, such as salty, sweet, partly aerobic, low acidic conditions typical of the environment at the beginning of a fermentation. Like most other lactobacilli, L. mesenteroides convert these types of sugars into lactic acid, acetic acid and carbon dioxide. The carbon dioxide dispels any remaining oxygen from the ecosystem, so that the conditions are appropriate for the strict anaerobes, which prevent the plant material from loosing its color and decaying.
The ecosystem inside your fermentation vessel is where one type of bacteria succeeds another, and each species adapts to the environment in such a way that appropriate conditions are prepared for the next. Each successive species has a better resistance to the acid environment, until L. Plantarum eventually comes to dominate. The sheer amount of lactic acid in the resulting ferment gives the product a sharp sour taste. Essentially, L. Plantarum creates a very stable bacteriological regime, which has a very low pH and which means few other bacteria or pathogens can survive, therefore preventing spoilage and creating a very durable product.
Process and supplies.
Some advanced ferments require sterilization of utensils to remove any probability of contamination or failure. But generally, don’t sweat it! Just make sure your work surfaces and utensils are cleaned with a mild (preferably natural) disinfectant. Remember, fermentation is an ages old technique, carried out in less than sterile conditions. The lactobacilli are a hardy bunch that will overcome many a bit of grime.
Most fermentation methods ask for water and salt. Modern day, urban water supplies are often contaminated with chlorine, which can inhibit the fermentation process. If you do not have a modern filtering system, or want to use bottled water, you can purify the water by bringing it to the boil so that the chlorine evaporates and then letting it cool.
Salt and brine:
Salt is a key ingredient in fermentation and care should be taken to acquire a good, wholesome product. Refined salt contains artificially elevated levels of iodine and may be stripped of its natural and abundant mineral content. Use a good salt like Himalayan pink rock salt for optimum effect, but any unrefined sea salt will do.
Leafy vegetables like cabbage, due to their high water content, can ferment in their own juice. However it is sometimes more appropriate to ferment other, tougher vegetables in a pre-made brine.
Below is a useful guide for salting quantities and ratios:
Dry-salt method (as used in Sauerkraut for example): 1.5-2% weight of veggies, or roughly 1.5 – 2 teaspoons per pound (15-20Grams per 1KG of vegetables).
Brine method – 5% to weight of water, or roughly 3 tablespoons per quarter of a gallon (1.13ltrs). (5% = 50 grams of salt in 1 liter of water).
Grains – 1.5-2% weight of dry grains, or roughly 1.5-2 teaspoons/pound.
As you progress in fermentation, you will learn that many recipes just require salt to taste. But the above is a good guideline to get you started. Although, after a few mistakes of our own, Octopus Alchemy advises that you weigh out the salt quantities to avoid disappointment! Of course some ferments take place without salt, however salt helps the process enormously (Some Indian ferments for example rely on oil to inhibit unfriendly bacteria), providing additional preservation, flavor and texture. To encourage a slower fermentation process, always use more salt, compared for instance, to a ferment you want to be ready in a short time. A brine can also be flavored with spices, with some having their own anti-fungal properties and bringing their own beneficial strains of bacteria to the mix.
Some salty facts:
- By means of osmosis, salt extracts water from the vegetables. This helps create the watery environment for anaerobic bacteria to flourish.
- Salt makes the vegetables crisper because it strengthens pectin (a structural polysaccharide in plants) and pectin-degrading enzymes are inhibited.
- Salt reduces the environment in which different bacteria can survive and give salt-tolerant lactic acid bacteria an advantage.
1 teaspoon = 5 ml = 5 grams of salt
1 tablespoon = 15 ml = 15 grams of salt
A simple fermentation process.
- Cut, scrape or grate the vegetables.
- Choose appropriate salting method: either salt to taste, dry-salt or brine the vegetables.
- Place vegetables in your chosen fermentation vessel (buckets, jars and crocks are widely used – but get creative!) and compress firmly until they are submerged beneath the brine and ensure that all oxygen bubbles are removed. Tap the vessel lightly on the table a few times to facilitate this process, or use a few chopsticks to enable bubbles to escape. If there is not enough brine in the vessel, top up with a brine solution at the appropriate ratio (see brine method above). In smaller vessels, like jars, you can use folded up vegetable leaves to act as a plug to keep the ferment underneath the brine. You can also use a boiled stone or glass weights to hold the vegetables down. In bigger vessels, you can use a wooden plug or plate. For anyone lucky enough to have their own traditional fermenting crock, these come with their own fittings to keep the ferment safe under the brine. Check that there is in each vessel a 2 and 4 cm gap between the juice and the rim (fermentation needs space).
- Place in an appropriate place at ambient room temperature, out of direct sunlight.
- Wait, test, observe and enjoy!
*Bruising and cutting the vegetables for more salting will ensure that the plant nutrients are rapidly available for resident bacteria to begin fermentation. Of course, brining methods sometimes involve merely submerging whole vegetables and then leaving them to their own devices – this is fine too! But may take a longer time to ferment.
*There will be a significant build up of CO2 in the fermentation vessel and it is wise to “burp” your vessel to release built up gas for the first few days at least. Take care when eventually opening your ferment to eat for this very reason.
Fermentation is a cultural practice that developed fundamentally to preserve foods and ensure adequate nutrition for communities the year round. To that end, ferments can be left to fuse and bubble for the length of a season or more. However, most vegetable ferments can be eaten at 7-9 days and are wonderful at 20 days. Taste your evolving ferment with regularity to monitor its progress.
The process of fermentation is dependent on temperature. To warm an environment and the process will occur to quickly – and the ferment will have an inferior quality to one where the temperature is managed properly. Eventually, fermentation vessels will need to be moved to cool storage to slow down the process completely, and to preserve your vegetables for long periods. Knowing when it’s time to do that is all about investigation.
Leave your vessel in a place with an even temperature between 18 and 22° C for up to three of four days. After three of four days, consider moving the vessel to a cooler environment at around 15 – 18°C.
The fermenting vegetables will become lively and gaseous with CO2 bubbles easy to see in a vessel like a jar, or exploding onto the surface in a crock or container. The smell of the vegetables will also become pleasingly sour. After around 10 – 14 days, check the ferment for activity and smell – at this stage you might consider moving it into a cooler environment still, to slow down the process (under 15°C).
After three to four weeks – chances are the ferment will be reaching optimum acidity, and can be moved into cold storage (a refrigerator or larder below 10°C).
Alternatively, ferments can just be left to bubble for around 20 days at a stable room temperature, and will have reached a good acidity by 20 days and be either ready for consumption, or to be put in the fridge to keep for long periods. Whilst fermented vegetables can be eaten and enjoyed a week and even 20 days into the process, after 5 – 6 and even 12 weeks you will be left with a delicious product.
See what works for you!
Some people want to know when best to eat their ferments depending on when the bacteria content is at it’s highest. Lactic acid bacteria in fermented vegetables tend to follow a bell curve: “populations grow after vegetables are submerged, build to a peak, then decline at high levels of acidity”. The dominant species of bacteria also shifts as time goes on. The best approach in terms of consumption might be to tuck in to your ferment at different intervals to “diversify your bacterial exposure”.
Some basic guidelines and requirements for a lactic acid fermentation:
– A salt concentration of 0.8-2.5%
– A sealable fermentation vessel to restrict oxygen.
– A uniform starting temperature of 20-22 ° C for about 2 days for small glass jars and bottles and up to 10 days for large earthenware jars.
– A cooler temperature (15-18 ° C) for 10-14 days
– A storage temperature preferably below 10 ° C (frost)
Fungi and yeasts
Oxygen is counter-productive to the process of fermentation. To much oxygen in the fermentation vessel may mean that fungi appears on the surface of your ferment – this happens especially along the edges of open bowls or where vegetables come to the surface. Surface growth of fungi is common and normal – it is normally just fine to scoop the layer of fungi or mold from the surface to reveal a perfectly fine ferment underneath. Removing the layer of fungi will prevent it’s tentacles extending deep into the vegetables, and releasing it’s pectin and cellulose destroying enzymes, which may cause the ferment to perish. Preventing this from happening is all about being attentive to your ferments, using your senses and your common sense.
What can be fermented?
Fermenting vegetables does not end with Sauerkraut! Practically anything can be fermented, but of course there is some variation in taste and some things withstand the process better than others. The underlying principle to fermenting all vegetables is to create an appropriate environment for the process, which has already been discussed. Away from that, there is an incredible amount of variation. As Sandor Katz explains: “Some traditions wilt vegetables, either in saltwater brine or in the sun; others pound or bruise fresh vegetables. Some people ferment a single vegetable, while others mix a dozen different vegetables together, perhaps along with spices, fruit, fish, rice, mashed potatoes, or other additions”. This variation is not just limited to process but also to combination: a fascinating array of interpretations on taste and flavor stem from different cultural cuisines. The “Art of Fermentation” is a revival of different recipes from around the world, and an essential book for the kitchen – go get it! Incidentally, Wikipedia also do a fantastic list of fermented foods from around the world.
Ultimately, there really isn’t a vegetable that cannot be fermented but all will have different results. Cucumbers for example can go soft and soggy, as can summer squash – so it’s important to ferment them in small quantities / make them a minor addition to a combination of other vegetables. Chlorophyll rich plants (kale, collards etc) develop a strong characteristic taste, which will suit some people and not others. The most popular vegetables for fermentation are the tough and hardy kind harvested in the autumn.
Fermentation vegetable index.
Maybe try some of the vegetables below in your ferments and concoctions! And don’t limit yourself to what is available in the supermarket, or what is a product of agriculture. Get creative and forage some wild ingredients, which will bring great flavor and of course their own ecologies of wild bacteria to the mix. Even seaweed may be considered! But please be respectful when foraging, don’t decimate the crop and tread gently on the land. Fermentation is also a great strategy for gleaners, dumpster divers, freegans and the like – pick over vegetables that have been cast out, cut out any mold and process them. Be careful with vegetables that come from establishments known for questionable food ethics, the pesticide / preservative content of vegetables may not bode well for a good ferment.
Vegetables you can experiment with:
- Root vegetables: sweet potato, daikon, celeriac, parsnips, radishes, turnips, beetroot, salsify, Jerusalem artichoke (The inulin content of artichokes, which can cause a lot of wind, is broken down very well by fermentation), carrot, parsley root, burdock root.
* Note that beetroot being so sugary can encourage a very yeasty ferment, and therefore quite a syrupy brine.
- Flower-fruit vegetables: aubergine (fermentation gets rid of the bitterness), pickles, artichoke hearts, cauliflower, broccoli, cucumber, okra, sweet and crisp peppers / chillies, pumpkin, green and red tomatoes (tomatoes fermented can become very acidic and are considered a Jewish delicacy), cut and green beans.
- Leaf-stalk vegetables: Kohlrabi, bamboo shoots, prickly pear, onion, cauliflower, chard, leeks, ramsons, fennel, chard steal.
- Fungi ferment well too! Shiitake or any other mushroom can be added to a ferment with other vegetables for an interesting texture.
+ Fruits can be added to vegetable ferments too. Try adding applies, raisins, cranberries, wild berries, plums, quinces or dried fruit to sauerkraut for example. Even watermelon rind can be used.
For an extra crunch – throw some nuts in!
- Condiments and spices: garlic, ginger and various spices such as juniper inlay, coriander, dill (fresh leaves and flowers, flower heads, dried seed), mustard and caraway seeds, star anise (with beets!), turmeric, cinnamon, cardamom (with cauliflower and carrots!), black pepper and sea salt; lemongrass and lime leaves.
* Some spices have an antifungal effect, and have their own healing properties. Get creative with your brining.
*Garlic is a popular seasoning; often it turns blue during fermentation, which is a reaction of the anthocyanin’s present, which reacts with the traces of copper in drinking water. Garlic is known not to preserve very well under oil because it may contain spores of the botulism bacterium. However, when garlic is under brine, there is no danger of botulism.
- Fresh vegetables can be combined with bean sprouts or other sprouted legumes or with cooked products such as rice, other cereals, boiled or baked potatoes and purees, and even hard-boiled eggs.
Get creative, get excited and get fermenting!
To access this booklet in full click here – or just to see the next section of recipes, click here.