Can fermented foods really be better than fresh ones? What makes fermented food beneficial for digestion, and how should it be prepared to avoid food poisoning?
Rotting or Delicacy?
The most alarming example of fermented products might be preserved duck eggs. This Chinese delicacy is known by names like “century eggs,” “thousand-year eggs,” or “imperial eggs.” Their distinctive features include a black color and a musty smell. However, this nutritious and beneficial product is not spoiled; it remains edible and can last for years without going bad. Those who have overcome their initial hesitation and dared to try it report that the taste of a “rotten” egg is salty, and otherwise, it is not much different from a regular boiled egg, except for a slight bitterness.
Various methods of preparing these eggs involve immersing them in an alkaline environment and preventing air exposure. Fresh duck, quail, or chicken eggs are coated with a mixture of quicklime, clay, ash, tea, and salt, then wrapped in straw and rice husks, placed in baskets, and buried underground. Eggs that have been aged in such conditions for three weeks to four months develop a strong odor; this unpleasant smell arises because, under the influence of sodium hydroxide, hydrogen sulfide and ammonia are released during fermentation.
Asians consider “century eggs” to be tasty and nutritious, serving them sliced as a traditional appetizer or using them as an ingredient in salads and more complex dishes. In addition to the ancient method of preserving eggs, they also utilize modern preservation techniques. Unlike pickled eggs preserved in vinegar (also a Chinese recipe), fermented eggs must be preserved in a salt solution. The brine and starter culture create an anaerobic environment that promotes the growth of beneficial probiotic bacteria on the surface of the eggs.
Why do bears and other predators bury their prey instead of eating the meat or fish fresh? Because fermented products are easier to digest. Specifically, two processes can occur in meat: either it is broken down by microbes, or the tissues soften due to their own enzymes (the self-digestion of dead cells is called autolysis). Despite the breakdown of substances, fermented products do not become inedible. It all depends on the prevailing microorganisms. During fermentation, natural preservatives are produced that prevent the proliferation of putrefactive bacteria.
How do Icelanders prepare their traditional dish hákarl, or “fermented shark”? Fresh meat from Greenland sharks is placed under pressure for several weeks or months, and then air-dried for an additional two to four months. It turns out that due to the high urea content, fresh shark flesh is toxic, but under the influence of microbial enzymes, ammonia promotes the alkalization of the meat, causing it to smell but not rot. Thus, fermentation is not simply about food going bad; the distinction between spoiled food and delicacy can be quite subtle.
What Do Fermented Foods Taste Like?
Fermented meats include cured sausages, jamón, and Parma ham. In various recipes, protein products can be preserved in their fresh state or after preliminary processing before fermentation begins (for example, smoking). Similarly, fermented meat can undergo further cooking. Delicate steaks are aged under controlled conditions (at fixed temperatures and humidity) for several weeks to months, allowing protein breakdown through enzyme formation.
Most fermented products share a common characteristic: their taste and aroma are more pronounced than that of the original raw materials. Almost anything can be fermented: meat, fish, eggs, milk, tea, herbs, vegetables, fruits, beans, nuts, and grains. Fermentation, as an ancient food preservation technique, extends the shelf life of products without losing their beneficial properties. Wine, cider, kvass, apple cider vinegar, kefir, yogurt, cheese, soy sauce, sourdough bread, sauerkraut, pickles, and homemade sausages are all examples of fermented products. For creative cooks, fermentation is a way to create new flavors from familiar ingredients.
Practically all Asian cuisine is based on the so-called “fifth taste” – known as “umami.” This is the taste of glutamic acid, which can be increased in various products through fermentation. “Umami” is the flavor found in soy, fish, and oyster sauces, as well as in fish or shrimp miso paste. Additionally, Asians use many varieties of fermented soybeans, which differ in flavor due to the various bacterial or fungal cultures involved in their processing. The same soy sauce can have radically different flavors due to fermentation, ranging from the delicate nutty taste of Indonesian tempeh to the rich chocolate flavor of Japanese fermented natto.
If exotic fermented products make us wary, it simply means we need to get accustomed to the off-putting smells and tastes. However, it’s not necessary to focus solely on what seems unappealing. Gastroenterologists consider the most beneficial fermented products to be sauerkraut and kimchi (fermented napa cabbage in Korean cuisine) – not only are they delicious, but they are also incredibly “fertile” in producing colonies of beneficial gut bacteria. Such foods contain probiotics, prebiotics, and fiber, which transform during fermentation into new forms that strengthen gut health.
Experts explain that fermentation is not just about adding bacteria; it involves transformation, particularly in the creation of acid. This is why sauerkraut has a bitter taste, not just salty. Fermented plants have become the trendiest foods in modern cuisine. While sauerkraut and kimchi rank at the top due to their optimal combination of three components, experts have classified popular fermented tea kombucha (tea fungus) as a product with limited benefits. While it supports hydration and energy, this sweet and sour drink has the advantages of fermented food, but due to its high sugar content, it should be consumed in moderation.
What is Fermentation in Simple Terms?
This process occurs differently in various products, but the essential rule is that changes happen without human intervention: one just needs to initiate and control it. The microorganisms involved in altering the properties of the product can be naturally present or added specifically to achieve the desired effect. When it comes to fermentation, the microbial culture is either intentionally introduced into the product or forms naturally. For example, yeast settles on fruit skins on its own, while for lactic acid fermentation in cheese making, rennet is also added.
What distinguishes fermentation from pickling? In fact, nothing. Unlike pickling, which involves submerging vegetables in brine, during fermentation, only salt is added, and the vegetables are pressed or weighted down. In fermentation (or pickling), beneficial lactic acid bacteria multiply in the juice that is released. To promote the growth of microorganisms, appropriate temperature conditions must be created, as bacteria “sleep” in cold (if the temperature is below 4°C) and die at excessively high temperatures (above 65°C).
Often, fermentation refers to the process of controlled fermentation, where yeast, mold, or lactic acid bacteria convert carbohydrates in food (sugar and starch) into natural preservatives – alcohol, lactic acid, or acetic acid. Alcohol and acids give fermented products their tartness and distinctive flavor. However, fermentation is a broader concept than just fermentation. In gastronomy, it encompasses other similar processes occurring in vegetables, grains, milk, eggs, fish, and meat.
In meat or fish, fermentation is caused by the partial breakdown of proteins due to the activity of their own enzymes, which is not fermentation. Overall, fermentation is the breakdown of organic substances under the influence of bacteria or through the action of enzymes (protein catalysts). Fermentation can be aerobic (with oxygen) or anaerobic (without oxygen). This process triggers the growth of beneficial probiotics: bifidobacteria or lactobacilli. Thanks to their ability to survive in acidic environments, lactic acid bacteria become a natural preservative that protects fermented vegetables from further decay.
However, beginners should not experiment with meat, fish, and cheeses: fermenting animal products requires preparation, adherence to conditions, and equipment, such as a dehydrator, cold storage, or at least a cool pantry. It is crucial to prevent soil particles from contaminating the fermenting products, as this poses a risk of botulism. The culprit of poisoning is botulinum toxin, produced by one of the soil bacteria in the absence of oxygen. In Latin, botula means “sausage”: the first documented case of botulism in the 18th century was caused by blood sausage. However, more often than not, this insidious microbe proliferates in homemade preserves without access to oxygen.
The Benefits and Harms of Fermented Foods
While recommending the consumption of fermented foods during fasting or strict diets, doctors caution that some individuals should avoid fermented products altogether. In particular, such foods are contraindicated for those with allergies. They can exacerbate gastrointestinal diseases: for example, a high fiber content can lead to increased gas production and bloating, while vinegar can be harmful in cases of ulcers and gastritis. Salt is often used in fermentation, which retains fluid in the body and can cause swelling, critical for kidney and cardiovascular diseases.
Fermented vegetables are contraindicated in hypertension, as biogenic amines (histamine and tyramine) are formed during fermentation, which dilate capillaries and affect heart rate. Pregnant women and nursing mothers are also advised against consuming kombucha (tea fungus), not only due to its sugar content but also because this fermented drink may contain ethyl alcohol, which poses a health risk to infants even in small amounts.
At the same time, fermented products are low in calories and are considered an acceptable choice for weight loss. Fermented vegetables are rich in beneficial micronutrients and fiber, which helps curb hunger. They are a treasure trove of vitamin C, which stimulates the production of elastin and collagen. Thanks to kimchi, soy sauce, and pickled ginger, Korean women maintain youthful skin for longer. These products can enrich the diet with probiotics, which help filter toxins and eliminate them from the body.
As a result, liver and kidney function improves, metabolism normalizes, food is better absorbed, and sleep quality is enhanced. Probiotics improve digestion, strengthen immunity, and support heart health. Their primary beneficial property is promoting the body’s self-regulation. The gut microbiota consists of 50 trillion bacteria – more than the total number of cells in our body. When harmful microorganisms outnumber beneficial ones, dysbiosis occurs. This imbalance can lead to diarrhea, constipation, allergies, obesity, and other metabolic issues.
Moreover, bacteria produce special compounds that act as neurotransmitters, regulating our mental and emotional states: they can “program” anger or joy, satisfaction or discomfort. The connection between the gut and the brain has long been established, and recent studies have explored the role of fermentation in increasing colonies of beneficial gut bacteria capable of enhancing mood, memory, and cognitive resources. Among fermented products beneficial for brain health and mood, researchers have identified yogurt with honey, kimchi, and kombucha.
Thus, by incorporating fermented foods into our daily diet, we can enhance our appearance, mind, spirit, and overall well-being.