"Shit" suddenly appears in the ingredient list of stinky tofu. Is it really an ingredient?

Key Points

★ The weird words that accidentally appear in the ingredient list are actually photoshopped and a prank, so don’t believe them.

★ Bottled "Qing Fang" is a fermented stinky tofu, while street-side fried stinky tofu is a non-fermented type.

★ Fermented stinky tofu has a relatively high nutritional value, but the salt content is not low, so it is not advisable to eat too much at each meal.

★ The safety of fried stinky tofu is difficult to guarantee. It can be eaten occasionally to satisfy your craving, but it should not be eaten frequently.

Not long ago, a netizen posted a video on a short video platform showing the ingredients of a certain brand of stinky tofu. The word "shit" was written on it, which scared many netizens! Not only did the original video itself have a strong smell, but even the comments section was "extremely strong". People said: "I dare not eat it anymore. I have eaten two bags and I still can't taste it..."

▲Picture: Screenshot from the webpage

▲Picture: Screenshot from the webpage

I have to say: one person really dares to send it, and a group of people really dare to believe it.

Because stinky tofu has a rather "pungent" taste, some people suspect that its taste comes from an unknown source. But what is the truth? How did this intoxicating odor capture our hearts?

01 Is the content in the video true? It’s just a silly prank!

Based on the product pictures in the video, the author searched for this brand online and found the same stinky tofu. He then followed the clues and discovered that this spoof had been discussed online as early as 2018, and three years later, some people were still posting it to attract traffic.

▲Picture: Screenshot from the webpage

After verification by relevant departments, it was found that the ingredient list in the video was tampered with through photo editing. There was no "shit" in the original ingredient list. The real ingredient list is shown in the picture below:

▲Picture: Screenshot from a brand e-commerce

Since it has nothing to do with "shit", how does stinky tofu get its "stink"? Is it true, as the folk rumor says, that tofu becomes stinky tofu after it is left to stink?

02 How to make authentic stinky tofu? The two major types have their own methods

The stinky tofu we are talking about can be divided into two types according to different production processes: fermented stinky tofu and non-fermented stinky tofu. Fermented stinky tofu is bottled stinky tofu, commonly known as "Qingfang", which can be bought in general large supermarkets; while the fried stinky tofu sold as street snacks is non-fermented.

Fermented stinky tofu is made from high-quality soybeans with a high protein content. It is made through a number of processes including soaking, grinding, removing dregs, curing, early fermentation, pickling, brine preparation, and late fermentation. During this process, "good mold" will grow through natural fermentation. [1]

The production process of non-fermented stinky tofu is as follows:[2]

Simply put, the difference between the two is that one is naturally fermented, while the other is made by soaking and fermenting in smelly brine.

03 Why does it smell bad but taste good? I am who I am, a different kind of "fireworks"

"Smells bad, tastes good" is one of the characteristics of stinky tofu. Many people refuse to eat it because of its stench, but some people love its unique flavor. In fact, the irresistible charm of stinky tofu is mainly due to the various changes it undergoes during the fermentation process.

Some people have conducted special research on the strong smell of stinky tofu. The results show that: from the concentration and threshold of the volatile components identified in stinky tofu, indole, sulfur compounds (dimethyl disulfide, dimethyl trisulfide, dimethyl tetrasulfide, 2, 3, 5-trithiahexane), alcohols, phenol, etc. contribute the most to the aroma characteristics of stinky tofu. They all have their own "contributions". Among them: [3]

Indole: The content is about 30%. Well... the same component does exist in feces, so the higher the indole concentration, the stronger the smell of animal feces. It is the main source of the stinky smell of stinky tofu.

Sulfur-containing compounds: including dimethyl disulfide, dimethyl trisulfide, dimethyl tetrasulfide, and 2, 3, 5-trithiahexane, which provide the smell of stinky carrots and stinky onions.

Phenol: The content is about 20%, which will enhance the odor, but it also has bactericidal and preservative effects.

Alcohols: Give stinky tofu a mellow smell.

Esters: Give stinky tofu a fruity, sweet smell.

It is precisely because stinky tofu combines all of these characteristics that it creates a unique and bizarre taste aesthetic of "smelling stinky but tasting delicious".

04 What are the nutritional values ​​of stinky tofu? Even if it is stinky, it must be "justified"

Although stinky tofu is notorious, it is actually very nutritious!

First of all, stinky tofu is a soy product. Its raw material is soybeans, which naturally have the characteristics of high protein, low fat, and rich in calcium. After the fermentation process, the protein is broken down into small molecules of amino acids, which are more conducive to the body's absorption and utilization. At the same time, the fermentation process also produces some vitamins, such as vitamin B12. This nutrient is generally more abundant in animal foods and is easily lacking in vegetarians. Studies have shown that the lack of vitamin B12 in the human body will accelerate the aging of the brain and induce Alzheimer's disease. [4]

Therefore, we usually recommend that vegetarians increase their intake of fermented soy products appropriately.

05 Is street fried stinky tofu nutritious? It is harmful to health, so eat less

Although stinky tofu is a nutritious food, deep-fried stinky tofu sold on the street is different and is not recommended for regular consumption. There are four main reasons for this: [2]

① Unsafe additives: In order to seek higher profits, some unscrupulous vendors may use cheap pigments, illegal additives, biogas digesters, etc., which may cause excessive levels of E. coli in the food ingredients. There may also be Salmonella, Shigella, Staphylococcus aureus, etc., which will endanger health after consumption.

Even if we exclude the use of improper means, fried stinky tofu should be consumed within one day, not the next day. This is because studies have shown that after frying, the total number of bacteria and E. coli in the finished product is very low on the day, but after one day, the total number of bacteria and E. coli will increase rapidly.

② Unsafe oil: It is difficult to replace the cooking oil for frying stinky tofu frequently, especially for individual vendors. They often fry the tofu in one pot many times and do not replace the oil for a day or even several days, which leads to an increase in the content of carcinogens. For example, there is clear evidence that the content of benzopyrene, which is carcinogenic to humans, will gradually accumulate.

③ Environmental pollution: Street food is sold on the roadside or in front of schools or shopping malls with high traffic, and is inevitably contaminated by street dust, microorganisms, etc.

④ High oil and high salt problem: Street fried stinky tofu is not only for preservation and to cater to the public's taste, but also for deep-frying, which not only destroys the nutritional content, but also has the characteristics of high oil and high salt. Frequent consumption will not only lead to weight gain, but also increase the risk of chronic diseases.

As for fermented stinky tofu, although its nutritional value is improved after fermentation, its salt content is also high, so you should not eat too much at one time. According to the data in the "Chinese Food Composition Table (Second Edition)", the sodium content in every 100 grams of stinky tofu is 2012 mg. The average piece of stinky tofu sold on the market is about 10 grams, and eating one piece is equivalent to consuming about 0.5 grams of salt. Some people eat one piece at every meal, so they will consume about 1.5 grams of salt for three meals a day. If you don't control the amount of consumption, it will not only be unfriendly to controlling blood pressure, but a high-salt diet will also increase the risk of gastric cancer. [5]

The results of the 2012 Chinese Residents’ Nutrition and Health Status Monitoring Program showed that the national average daily salt intake was 10.5 grams per person; a 2015 survey showed that salt intake had dropped to 9.3 grams. However, even so, it still exceeded the recommended salt intake of less than 6 grams per day (about one beer bottle cap) in the Chinese Dietary Guidelines[5]. The World Health Organization recommends that salt intake be less than 5 grams per day.

Summarize:

For those who like to eat stinky tofu, you should be careful not to eat too much while enjoying the delicious taste, after all, the salt content is not low. If you eat stinky tofu on the same day, you should pay attention to reducing the amount of salt you consume.

If you like to eat fried stinky tofu on the street, it is recommended that you eat it occasionally to satisfy your craving and try to choose snacks that are legally operated indoors, as their quality and safety are more guaranteed.

Finally, a warm reminder: if you buy bottled fermented stinky tofu, make sure to tighten the lid and store it in the refrigerator!

References:

[1] He Li. Research on production technology and nutritional value of fermented stinky tofu. South China University of Technology, 2012.

[2] Wang Longxiang. Safety analysis and research of fried stinky tofu[D]. Central South University of Forestry and Technology, 2012.

[3] Liu Yuping, Miao Zhiwei, Huang Mingquan, Chen Haitao, Sun Baoguo. Extraction and analysis of volatile aroma components in stinky tofu[J]. Food Science, 2011, 32(24): 228-231.

[4] Li Shengfeng. Research on the nutritional value and functional development of stinky tofu[J]. China Agricultural Information, 2013(05):142.

[5] Liu Na, Shen Yueping, Li Baoxia, et al. Meta-analysis of the relationship between high-salt diet and pickled food and gastric cancer[J]. Environmental and Occupational Medicine, 2009(03):263-266.

[6] Chinese Nutrition Society. Dietary Guidelines for Chinese Residents[M]. People's Medical Publishing House, 2016

Author | Xue Qingxin, member of Chinese Nutrition Society, registered dietitian, registered nutrition technician, health manager, public nutritionist

Review | Sun Licui, Researcher, Institute of Nutrition and Health, Chinese Center for Disease Control and Prevention

This article was first published on Science Refutes Rumors