What do you think of when it comes to fermentation? Is it "notorious" stinky tofu or sour and delicious sauerkraut? Of course, we can’t help but mention "hairy tofu", a traditional famous dish in Anhui.
"Fermentation", a name that sounds mysterious, actually has a very high usage rate in daily life. For example, steamed buns made by yeast fermentation, yogurt and pickles made by lactic acid bacteria fermentation, fermented bean curd made by mold fermentation and so on.
Image material source SOOGIF
Fermented food is a kind of food with unique flavor, which is processed by some special microorganisms. According to incomplete statistics, there are more than 5000 kinds of fermented foods (including drinks) in the world.
A study in the United States (IF: 41.58) suggested that eating other fermented foods such as yogurt, fermented cheese, vegetable brine drinks or pickles can not only enrich the diversity of flora in the human intestine, but also reduce the inflammatory markers in the human body.
The International Association of Probiotics and Probiotics (ISAPP) also shows that besides the nutrition of food raw materials, the activities of related microorganisms during fermentation can also improve the nutritional value of food or produce bioactive substances, which interact with human intestinal flora and immune system. Food fermentation can also remove toxic or anti-nutritional components from raw materials and improve food safety and nutritional quality.
It is worth noting that at present, except dairy products, few other foods have been randomized controlled trials (RCT) to verify their benefits to human health. Many studies have proved that yogurt has a positive impact on human health, and the evidence that some fermented foods promote health is mainly limited to chemical analysis and animal/cell culture models.
Original image source: NAT Rev Gastroenterol Hepatol.2021; 18(3):196-208.
Most lactic acid bacteria, yeasts and filamentous fungi used in food fermentation are non-pathogenic and will not produce toxins or harmful end products.
However, in the process of fermentation, there are many uncontrollable factors that may affect food safety. For example, in the fermentation process of fermented bean curd, if the hygiene is not up to standard or the operation is not standardized, and the fermented bean curd is polluted by miscellaneous bacteria, it may cause the fermented bean curd to stink and affect the safety and quality.
In addition, cheese, meat, vegetables and wine fermented by lactic acid bacteria will produce histamine, tyramine and other biogenic amines. For people with histamine intolerance, excessive intake may lead to migraine, increased heart rate, rhinitis and runny nose.
At present, most countries do not explicitly recommend fermented foods, except India, which encourages pregnant women to eat more fermented foods. It is suggested that while diversifying the diet, residents’ dietary guidelines should be taken as a reference, and the characteristics of fermented food should be adjusted, for example:
The guide suggests:
On average, 300g of liquid milk and more than 25g of soybeans are supplemented every day, or a considerable amount of milk/soybean products.
Because alcohol and high salt are inherent components of some fermented foods, it is not advisable to take too much from the health point of view.
The guide suggests:
The daily alcohol intake of adult men is not more than 25g, and that of women is not more than 15g；; Salt per capita does not exceed 6g per day.
To sum up, when choosing high-salt fermented food, it is best to use it instead of salt as seasoning, or other diets should be as light as possible.
tea leaves
Fermented tea is a kind of tea making technology. The common green tea in daily life is unfermented tea, while black tea and oolong tea are fully fermented tea and semi-fermented tea respectively.
In the process of fermentation, the chemical substances in tea changed, and the tea was gradually mild, reducing the irritation to the stomach.
fermented bean curd
Sufu, douchi, soybean paste and soy sauce are also called the four traditional fermented bean products in China. Fermented bean curd contains vitamins B2 and B12 which are lacking in many plant foods. Vegetarian people can supplement vitamin B by eating sufu in moderation.
It is worth noting that the salt content of sufu is relatively high, so it is not recommended for patients with hypertension to eat more, or sufu can be used instead of other salty condiments.
Brewing vinegar
Vinegar is made from grains containing starch, such as sorghum and wheat, through a series of fermentation processes. Acetic acid will be produced in the fermentation process, accompanied by a faint fragrance.
When the appetite is poor or the taste and digestive function of the elderly decline, adding vinegar during cooking can not only improve the flavor of food, increase appetite, but also help digestion.
natto
Natto is full of nutrition, and the content of protein, vitamin B2, calcium and iron in every 100g of natto is higher than that of cooked soybean. Moreover, natto also has unique nattokinase, which has preventive and adjuvant therapeutic effects on myocardial infarction, cerebral thrombosis and other diseases.
However, at present, most of them are in vitro experiments and animal experiments, and whether it is effective for human body needs further study.
summary
Fermented food has certain benefits to human body, but it doesn’t need to be sought after too much;
The effect of yogurt on human health has been verified by many studies, and some other fermented foods need further study.
It is suggested that the diet should be diversified, the general principle of healthy diet should be grasped, and the intake of alcohol or high-salt fermented food should be paid attention to; Cultivate the good habit of checking the food ingredient list when buying;
At present, most of the regular fermented foods on the market have strict quality control and management and are safe. What needs to be careful is the possible microbial pollution caused by home-made fermented food.
Make sense of food
Source: Department of Nutrition, Shaw Hospital
Author: Huang Keren