Japanese who love fermented beans such as natto and miso are the longest-lived countries in the world. Fermented foods handed down from ancient times, such as red koji and kimchi in China, have been proved to have health preserving effects. However, the high salt content of these fermented foods is also questioned as unhealthy. Is fermented food beneficial or harmful to human body?

In the past, in order to prolong the shelf life of food, people came up with the method of pickling to preserve food. Most of these pickled foods use a lot of salt to inhibit the growth of bacteria and induce enzymes to ferment them. Although it has been proved that they have high nutritional value, in modern times, whether these fermented foods are beneficial to health has always been a question in many people's minds.

What is fermented food?

What is fermented food? Huang Shuhui, a nutritionist at the Postal Hospital, pointed out that under natural conditions, when salt or sugar is added to food, the enzymes of the food itself will start to work when it is isolated from the air, or some strains will be directly added to trigger a fermentation reaction to form fermented food.

When food is deprived of oxygen, the enzymes in the cells of the food itself begin to operate, which will change the nutrients in the food itself from macromolecules to small molecules. Protein will be converted into amino acids under the action of enzymes, and carbohydrates will be converted into sugar, vinegar and even alcohol. The fermentation process will give food a special taste. So pickles, miso, natto and soy sauce are all fermented foods.

Five advantages of high nutritional value

Fermented food has many benefits to human body. In addition to being easy to preserve, special amino acids will be released after fermentation, resulting in special flavor of food. More importantly, the molecules of nutrients will be smaller and more easily absorbed by the human body.

◆ Easy to absorb

The advantage of fermented food is to change the macromolecules of food into small molecules, which are easy to digest and absorb and improve the nutritional value. For example, yogurt turns milk protein into milk protein? Amino acids and polysaccharides become disaccharides, monosaccharides or lactic acid, and the body absorption rate will increase. It is better for the elderly and children to eat fermented food than the original one, and it is less likely to have diarrhea.

◆ Balance intestinal bacteria.

When you eat fermented food, you also eat beneficial bacteria, which are generally called "probiotics". Probiotics can still survive in the intestine, and more good bacteria and bad bacteria will be suppressed. These good intestinal bacteria can also synthesize vitamin B group and vitamin K, making intestinal bacteria more balanced.

◆ Improve immunity

Fermented food can eat a lot of enzymes in food, promote gastrointestinal peristalsis and help food digestion. Gastrointestinal tract, known as the second brain of human body, has a good function, which can improve the immune function of human body, balance the immune system response and reduce allergic overreaction.

◆ Reduce blood lipid and blood pressure.

Some fermented strains contain components that reduce blood lipid, such as red yeast and natto, which can prevent blood coagulation and inhibit thrombosis, and contribute to the health care of cardiovascular diseases. In addition, some fermented foods will produce organic acids such as citric acid and acetic acid. If vinegar is used, it can control blood pressure, eliminate fatigue and balance body pH; Fermented beans can also synthesize higher vitamin B group, which has higher nutritional value than the original food.

◆ Prevent cancer

Studies have found that eating more natto and improving the taste can prevent cancer in the intestinal system. Because natto and miso are bean products, rich in dietary fiber, and after fermentation, probiotics can inhibit bad bacteria and avoid the occurrence of cancer lesions, so it can prevent intestinal cancer. However, if you eat unclean strains, it will cause gastric cancer. Therefore, for Japanese people who love to eat natto and miso, the probability of getting intestinal cancer is low, but the probability of getting gastric cancer is much higher.

Foods high in salt and sugar should be eaten in moderation.

Although fermented food has many advantages, Huang Shuhui emphasized that fermented food is a bit like a double-edged sword. If fermented food is clean and hygienic, the nutritional value of food will be high. However, if the fermentation process is not handled properly, bad strains will come in, resulting in poor fermentation conditions, which may be counterproductive. Therefore, the premise of making fermented food is to keep the environment clean and hygienic, keep the temperature constant and clean, and let the strains in, which is safe.

In addition, because all fermented foods are high in salt or sugar, the content of sodium, potassium and phosphorus is high, such as hypertension, poor liver and kidney function, poor gastrointestinal tract, gastric ulcer, people with excessive gastric acid secretion and patients with chronic renal failure. These are not suitable for eating too much fermented food.

Not only these specific races, Huang Shuhui suggested that even healthy people should not eat too much fermented food every day. It is recommended to eat a small amount 2-3 times a week. Although fermented food has high nutritional value and is beneficial to intestinal health, enzymes can not completely replace intestinal digestive juice, so it should be eaten in moderation.

Pay attention to cleaning and preservation methods.

People should be reminded that although fermented food can have a long shelf life, it will also go bad because fermented food is always fermented. Once opened, it should be stored in cold storage and sealed, and should not be in too much contact with the outside air, otherwise bad bacteria will enter the head and continue to ferment, destroying the original probiotics.

Special attention should also be paid to the selection of fermented foods, and it is best to choose foods produced by tested food factories to ensure the quality is controllable. Huang Shuhui pointed out that it is not recommended to buy bulk fermented food because it is easy to be contaminated during transportation. Therefore, it is safer to choose vacuum packaging or canning.

If you eat it directly, you can eat beneficial enzymes.

As for how to eat fermented food or cook correctly? In fact, Huang Shuhui said, it is recommended to eat fermented food directly to obtain enzymes in food. If you eat it after heating, the enzyme will be destroyed, leaving only a special taste, such as miso soup, which can be eaten directly when mixed into sauce, while it is better to eat it directly as a side dish like a pickle pot. So if you want to eat enzymes, just eat them without heating.

Different fermented foods have different functions. Huang Shuhui pointed out that there are many strains of probiotics, and each strain has different functions, such as lactic acid bacteria in yogurt, natto bacteria in natto, monascus in monascus, acetic acid bacteria in kimchi and so on. There are different beneficial bacteria. Black tea is also a completely fermented beverage, and oolong tea is a semi-fermented beverage. As long as it is eaten in moderation, it is beneficial to the human body.

What is the difference between fermented food and moldy food?

Fermentation and mildew are very different. Fermentation is to control food in a specific environment and let specific strains grow. Molding means that bad bacteria grow out of order and breed. The most obvious is that white hair will grow on the surface.

However, fermented food also depends on the production process. It is fermented food that controls the fermentation environment well, and rotten food that fails. Huang Shuhui reminded that moldy food looks like mold on the surface, but in fact hyphae have already penetrated into the food, so don't continue to eat it to save money.

Jinhua ham, which is common in the market, will have a layer of white mold on its surface after air drying. If you eat bad bacteria, it will be harmful to your health, especially flavobacterium toxin. Therefore, before eating, you must first remove the white bacteria on the surface before eating.