Soy sauce, yogurt, tempeh, fermented bean curd...... Fermented foods are common in life. They are a type of food that humans skillfully process with beneficial microorganisms. Fermented foods are said to not only bring out the nutrients of raw materials, but also help reduce inflammation and strengthen immunity in the body. For this reason, many parents often prepare fermented foods for their children. So, is that really the case?
What are fermented foods
Fermented foods are foods that are made using microbial growth and the transformation of food components through enzymes. In daily life, staple foods such as steamed bread, bread, and fat cakes, condiments such as soy sauce, vinegar, soybean paste, and tempeh, side dishes such as fermented bean curd and kimchi, and products such as yogurt and black tea are all fermented foods.
Fermented food has a long history in mainland China, which not only gives food a unique flavor, enriches people's dietary choices, but also changes the original nutrients in the food and improves the nutritional value of food.
What are the common fermented foods in life?
Alcohol and fermented beverages: wine, fruit wine, fruit vinegar, etc.
Fermented grains: steamed bread, bread, pasta, vinegar, etc.
Fermented soy products: soybean paste, natto, fermented bean curd, etc.
Fermented vegetables: kimchi, sauerkraut, etc.
Fermented dairy products: yogurt, cottage cheese, etc.
Fermented meat products: sausages, cured meats, etc.
Does fermentation produce additional nutrients
Indeed, the benefits of fermented food can be summarized as follows: improve the flavor of food, increase aroma, preserve food through high salt, lactic acid bacteria, alcoholic fermentation, etc., can prolong the storage time of food, improve the nutritional value of food, and promote the absorption and utilization of nutrients. Let's take the following foods as examples.
yoghurt
Yogurt is made by fermenting pure milk, in addition to retaining the nutrients of fresh milk, fermentation will also decompose the lactose and protein in the milk into galactose, lactic acid, small peptide chains and amino acids and other small molecules that are easier for the human body to absorb. During the fermentation process, lactic acid bacteria can also produce a variety of vitamins necessary for the human body, such as vitamin B₁, vitamin B₂, vitamin B₆, vitamin B₁₂, etc. Studies have found that lactic acid, when combined with calcium, is most easily absorbed and utilized by the body. Yogurt creates an acidic environment in the gastrointestinal tract that aids in iron absorption.
Therefore, yogurt is suitable for developing teenagers. In addition, there are more people who are lactose intolerant on the mainland, and due to the lack of lactase, they are unable to break down the lactose in milk, and they will have symptoms such as bloating and diarrhea when drinking pure milk. This type of person is more suitable to drink yogurt to promote the digestion and absorption of food.
Flour products
Flour products use yeast to ferment the flour, change the structure of the dough, make it softer, improve the taste, and allow the nutrients in the food to be better digested and absorbed by the body. The flour products we usually eat are divided into dead noodles, raised noodles, and hot noodles.
Dead noodles Cold water and noodles, the kneaded dough is tough and has a chewy taste. It is often used to make hand-rolled noodles, dumpling wrappers, and wonton wrappers.
Yeast powder is added to the dough and fermented at a certain temperature. Common foods include steamed buns, bread, steamed buns, and dough cakes.
Hot noodles are made with hot water at different temperatures according to the processing needs. The higher the water temperature, the less tough and soft the dough will be.
For people with poor gastrointestinal function, eating food made with noodles is better digested, and the burden on the stomach is lighter. Food made from dead noodles can easily cause bloating, abdominal pain, and is not easily digested. Foods made with hot noodles fall somewhere in between. For healthy people, all three can be eaten.
Fermented soy products
Fermented soy products, such as soybean paste, fermented bean curd, natto, stinky tofu, etc., are soy products after microbial treatment, which not only retains the nutrients of the soybean itself, removes the bitterness and beany smell of soybeans, but also degrades the insoluble polymer substances existing in soybeans into soluble low-molecular compounds, such as protein degradation to produce polypeptides and amino acids, and improves the utilization rate of proteins and minerals.
Is it reliable to say that it strengthens immunity?
Recent studies have shown that the diversity of intestinal flora has increased significantly among people who consume fermented foods such as sauerkraut, kimchi, yogurt, cheese, fermented tea, and fermented milk drinks. Eating fermented foods can reduce the pro-inflammatory cytokines in the blood and inhibit the overreaction of immune cells.
It is important to note that the additional effects of fermented foods mainly come from probiotics, which are active bacteria that can only help maintain the balance of intestinal flora and improve intestinal health when they are active. Not all fermented foods have live probiotics, and if you really need to supplement with probiotics, it is recommended to choose a probiotic supplement.
Do fermented foods contain excessive nitrites
There are many types of fermented foods, and not all fermented foods have the problem of excessive nitrite. Excessive nitrite is mainly found in fermented vegetable foods.
Fresh vegetables contain more nitrate, which itself is not toxic, but after the reduction of bacteria during the fermentation process, nitrate becomes toxic nitrite. Normally, nitrite levels peak after a week of fermentation, and gradually decrease to a minimum over the next 20 days or so.
Although fermented foods are not the same as foods with excessive nitrites, people who like to eat kimchi and sauerkraut should try not to choose freshly pickled vegetables to eat. Fermented foods are safer to be marinated for at least 4 weeks before eating.
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Fermented foods are good and can be used as part of a balanced diet to increase food variety, but they must be consumed in moderation. When choosing fermented foods, you should pay attention to the following.
1. Fermented food has strict requirements for environmental hygiene and production standards, we must choose qualified regular manufacturers and platforms, and do not buy "three no" products.
2. In order to improve the acidic taste of yogurt products, some manufacturers will add a lot of sugar, we must pay attention to the daily intake of added sugar should not exceed 50 grams, and it is best to control it below 25 grams.
3. Some fermented foods, such as soybean paste, natto, bean curd, etc., are condiments, and the sodium content is generally high, so you should not eat more, and pay attention to reducing the intake of salt in other foods when eating these fermented foods.
4. It is recommended to control the consumption of kimchi at 20~30 grams per day, and marinate for at least 4 weeks before eating.
5. If you feel unwell after eating fermented food, stop eating immediately and seek medical attention as soon as possible. People who have eaten the same food but have not become ill should also seek medical attention as soon as possible.
Source: Public Health magazine
Text: Department of Clinical Nutrition, Union Hospital Affiliated to Tongji Medical College, Huazhong University of Science and Technology, Wu Yuanjue, Cai Honglin
Curator: Yu Yunxi
Editor: Chen Xiuchao, Qin Mingrui
Proofreading: Ma Yang
Review: Guan Zhongyao, Xu Bingnan