Fermentation is an ancient and simple method of food preservation.

It requires no special climate, no fuel consumption, and even no cooking. Most fermented foods require only a container, some brine.

The term "preserved foods" is used to refer to both fermented and unfermented food products.

Whether the ingredients are soaked in brine or stored using the food's own enzymes, the food is essentially preserved by fermentation: the brine aids fermentation, and the fermentation creates preservative acids.

Differences in diets around the globe have to do with local climate, sunlight, soil, and moisture. But fermented and preserved foods have been around for a long time on both ends of the Eurasian continent, which is a long way from each other.

Pickled cucumbers and olives, for example, have a long history.

The olive tree was first cultivated in the eastern Mediterranean about 5,000 years ago, probably to extract oil. Fresh olives are actually inedible because they are innately rich in bitter phenolics.

Later, people learned how to remove the bitterness from olives by soaking them in repeated changes of water. In Roman times, it was discovered that by adding alkaline wood ash to the water when soaking the olives, the time it took to remove the bitterness was reduced from weeks to hours.

The fermenting bacteria of olives are predominantly lactic acid bacteria, which also produce some yeast, which adds to the aromatic flavor.

Some olives are macerated at the green stage to remove the bitterness before being fermented, or they are fermented after the skin has turned a darker color and the bitterness of the olives has been muted by the presence of zeylanthocyanins.

Cucumbers are refreshing and delicious, produced in the summer. Crisp little cucumbers have a distinctive flavor when pickled, and many chefs like to use pickled cucumbers for flavor.

Most pickling cucumbers use thin-skinned seeds that are harvested while the cucumber is still ripe, and then the blossoms are cleaned and removed. There are microorganisms in both the blossom and the rhizome, and if you omit this step the ingredients are easily softened by the enzymes carried by the microorganisms. (Then it won't be crisp.)

Dip the cucumbers into salty water with a salt content of 5 to 8 percent, with the water temperature at 18 to 20 degrees Celsius, and pickle for 2 to 3 weeks. Pickled cucumbers will accumulate 2% to 3% salt and 1% to 1.5% lactic acid, which makes them very heavy in flavor.

So soak it before serving to flush out its salt and lactic acid, then add seasonings like vinegar. Pickled cucumbers should not be left out for long, but must be refrigerated and eaten as soon as possible.

There are also foods that are similar to German sauerkraut and pickled olives, such as preserved lemons, pickled plums, and pickled daikon radishes in South Africa; pickled vegetables in Japan; and big, spicy pickled fruits and veggies in India. ...... The ingenuity people put into their food should never be underestimated. Every time you arrive in a new place, there's always a way of eating food that you haven't seen before.

Kale (cabbage, bok choy, purple kale ...) The genus is the vegetable genus of choice for making kimchi.

German sauerkraut and Korean kimchi are not only well known, they also represent two cultures. The Chinese also eat kimchi, with kimchi in the Southwest and sauerkraut in the Northeast for a different flavor.

Many Asian pickles add a "yeast" that has been fermented. For example, older generations liked to use fermented noodles as a "starter" for steamed buns, or as a by-product of the brewing process for wine and soy sauce.

Japan likes to use rice bran to pickle vegetables (rice bran pickles), rice bran contains a lot of B vitamins, so pickled radish and other pickled vegetables are more nutritious.

The difference in food culture between the East and the West is also reflected in this little drowned vegetables.

The German sauerkraut and Korean kimchi have very different practices and flavors.

Sauerkraut means "sour kale" in German. Sauerkraut is made by chopping up spherical kale (cabbage), adding a pinch of salt and placing it at cool room temperature where it ferments.

German sauerkraut is mainly used to accompany big fish and meat, and is pickled very sour, but also because of certain yeasts produced by the fermentation, this refreshing little dish has a hint of flavor.

Korean kimchi, by contrast, is more heavily flavored.

Korean kimchi is made by fermenting whole slices of cabbage with chili peppers and garlic, and adding fruits such as apples, pears, and melons, as well as fish sauce or shrimp paste, depending on the flavor preference.

Korean kimchi is salted more and fermented at a lower temperature than German kimchi. Because early Korean kimchi was made in late fall and winter, people sealed the ingredients in jars after making it and half-buried it in cold soil or put it in a cellar at a temperature of about 14 degrees Celsius or less.

Because of the low pickling temperature, the gas-producing bacteria in kimchi are dominant, and bubbles are easily produced.

Korean kimchi is crisp and spicy, and much saltier than German sauerkraut. This is also related to the Korean diet, which makes kimchi ideal for serving with rice.

German Sauerkraut

Ingredients: cabbage, salt

Fermentation Temperature: 18-24 degrees Celsius

Fermentation Time: 1-6 weeks

Final Salt Content: 1-2%

Final Acidity: 1%-1.5%

Characteristics: Sour, aromatic.

Korean kimchi

Ingredients: cabbage, salt, chili peppers, garlic, seafood sauce

Fermentation Temperature: 5-14 degrees Celsius

Fermentation Time: 1-3 weeks

Final Salt Content: 3%

Final Acidity: 0.4-0.8%

Specialties: heavy flavor, crunchy, and crispy. Characteristics: Heavy, crunchy and spicy

In fact, most pickled fruits and vegetables are eaten raw, and the crunchier the texture, the better.

If unrefined sea salt is used in the pickling process, the finished product will have a crunchier texture.

Because unrefined sea salt is rich in impurities such as calcium and magnesium, which encourage cross-linking of fibers within the plant and strengthen cell wall pectin. It tastes crisper and chewier.

There are also a lot of people like to add alum when pickling cucumbers, the reason is that alum contains aluminum ions, which can cross-link with the cell wall pectin.

Some kind of beneficial microorganism (lactobacilli) evolved in the anoxic environment of ancient piles of decaying plants.

The plants themselves are natural habitats for this beneficial microbe, and when the fruits and vegetables are drowned in an anaerobic environment, they proliferate and suppress other disease-causing, spoilage-inducing microbes.

When fruits and vegetables are preserved by fermentation, the beneficial microorganisms consume the metabolized sugars in the fruits and produce a variety of anti-microbial substances, including lactic acid, other acids, carbon dioxide, and alcohol.

At the same time, carbon dioxide is produced to protect against oxidative damage, so vitamin C is not damaged; they also often produce large amounts of B vitamins, which create new volatile components that add flavor to the food.

The incredibly useful lactobacilli are now used in all sorts of food magic, turning milk into yogurt and cheese, and ground meat into sausage.

The character of a marinade depends on the concentration of salt and the temperature of fermentation, which determine which group of microorganisms dominates the scene and what they produce.

Some fruits and vegetables can be left to ferment in sealed jars on their own, but most are sprinkled with dry salt or soaked in brine. The brine encourages the plant tissues to release water, sugars, and other nutrients, while also providing liquid to submerge the fruits and vegetables, limiting their contact with oxygen.

So if there's a problem with the vegetable fermentation method, it's usually because it's not salty enough, it's not warm enough, or it's been exposed to air. All of these situations invite unwanted microbes.

In particular, vegetables that are not fully buried in the maceration solution or the solution is not sealed properly can lead to discoloration, softening, breakdown of fats and proteins, and a rancid odor.

Even the beneficial Lactobacillus germinatus can produce a pungent, acidic flavor if the fermentation is too strong or too long.