writing / Chen Junshi, researcher of National Food Safety Risk Assessment Center, academician of Chinese Academy of Engineering. First round Kexin Food and Nutrition Information Exchange Center 。

In life, we often hear about "junk food", and the media will sort out various lists of "junk food". Instant noodles, French fries, cola, hamburgers, fried chicken, ham, etc. are generally on the list. Many people love and hate "junk food", and many people simply stay away from it.

I am not very interested in "junk food" or have a lot of research on "junk food", but on many occasions, media friends have asked me about my views on "junk food", and here I will write some of my views for your reference.

The term "junk food" comes from the English word junk food 。 According to the Oxford Dictionary, junk "" means something that is useless or worthless, and " junk food Is "Junk food" (food that is easy to make and eat but harmful to health). In the West, it first referred to fast food such as hamburgers and French fries, and later expanded to carbonated drinks such as fried chicken and cola. In China, I don't know when instant noodles and fried dough sticks were also honored to be selected.

Before discussing whether "junk food" is harmful to health, it needs to be clarified that the so-called "World Health Organization（ WHO ）The publication of the list of the world's top ten junk foods is not true, The World Health Organization has refuted the rumor and never released the list of the worst food or junk food 。

The reason why people include hamburgers, French fries, fried chicken, cola and other foods in the list of "junk food" is, of course, that they have one common feature: from the perspective of nutritional composition, they contain high energy and / Or high fat, but few vitamins, minerals and other nutrients; If you eat more and often, it will easily lead to weight gain and obesity.

However, are the above foods the only ones with high energy and fat?

I checked two thousand and two and two thousand and four Chinese food ingredients in one hundred Calculate the grams (milliliters) of edible parts, and list the contents of major nutrients of several related foods respectively, as shown in the following table.

From the table above, we can see that the popular foods such as Beijing Roast Duck and Roast Mutton Kebabs have high energy and fat content, which seems to conform to the characteristics of "junk food"! For example, every one hundred The energy content of Peking Roast Duck is almost the same as that of hamburger two The fat content is also hamburger two Times more. The energy and fat of the kebabs are not low, but the protein content is relatively high.

As such, should we include Beijing Roast Duck and Roast Mutton Kebabs in the list of "junk food"? Then, will traditional Chinese dishes such as braised pork, lion's head and boiled fish also be on the list? In this case, is the list of "junk food" too long and against everyone's "perception"?

I think we should think deeply about whether it is appropriate to copy foreign terms in China.

As nutritionists, we never think that food is good or bad (that is, "junk food" and non junk food), because Whether a person eats nutritionally and healthily depends on whether the food collocation is reasonable. For example, if I eat hamburgers at noon, I should eat more vegetables at night. Similarly, after eating instant noodles at noon, we will add some meat and vegetables that night. There is too much fat in braised meat, but it is not impossible to eat it. As long as you don't eat more and eat it every day, it can be a part of a balanced diet. Of course, on the positive side, the term "junk food" generally summarizes the characteristics of some foods with high energy and fat, which can remind people to control their "appetite" for it, but it is not completely untouchable.

There is also a misunderstanding that needs to be clarified. Nowadays, overweight and obesity are increasingly blamed on the consumption of "junk food", especially sweet drinks such as hamburgers, hot dogs, French fries and colas. There are many reasons for overweight and obesity. Even in terms of diet, it occurs because the total energy is "unbalanced", that is, the intake is far more than the expenditure. Therefore, in order to maintain a healthy weight, we should not only control intake, but also "dare to spend". Occasionally, if you eat too much, you should strengthen exercise and consume the energy you eat more. To put it bluntly, weight control is a problem of healthy lifestyle. You just blame it on a few food types. Are you sure you are not making excuses for your "laziness"?

In short, “ "Junk food" is not a scientific definition. There is no distinction between "junk" and "health" in food itself. There is no junk food, only the combination of junk 。 Of course, consumers can still learn more about the nutritional characteristics of various foods and try to follow the recommendations of the Dietary Guidelines for Chinese Residents. For example, according to the "Balanced Diet Pagoda", we should diversify our food, eat some of each food and not eat more of each food.

reference material:

[1]       Chinese Food Composition Table two thousand and four

[2]       Chinese Food Composition Table two thousand and two

    Wen/Chen Junshi, researcher of National Food Safety Risk Assessment Center, academician of Chinese Academy of Engineering.

First round Kexin Food and Nutrition Information Exchange Center 。

     To ensure food safety is like fighting a war, we must first recognize the main enemy. If we use great experience to deal with secondary enemies, it will be bad. What is the main enemy of food safety? At present, food borne diseases are the main enemies of food safety in the world and China (according to the data provided by American scholar Snyder in 1998, biological hazards account for more than 95% of the hazards in food supply).

What is foodborne disease?

What is foodborne disease illness）？ Generally speaking, it means food poisoning, which is typical of "upset stomach". In a year, a considerable number of people sometimes have "stomach trouble". Most of them are caused by eating food contaminated by pathogenic microorganisms. The definition given by the World Health Organization is a disease caused by various pathogenic factors that enter the human body through food intake, usually with infectious or toxic properties. Everyone is at risk of foodborne diseases.

　　 How serious are foodborne diseases?

Foodborne diseases, which cover a wide range of diseases, are an increasingly serious public health problem worldwide. The ingestion of food contaminated with microorganisms or chemicals can cause this disease. From food production to consumption (from farmland to dining table), food pollution may occur at any stage, which may also be the result of environmental pollution, including water, soil or air pollution.

The most common clinical manifestation of foodborne diseases is gastrointestinal symptoms; At the same time, this disease may also have other symptoms such as neurology, gynecology and immunity. The ingestion of contaminated food may also cause multiple organ failure in the whole body, or even cancer, thus causing great disability and death.

An active surveillance of foodborne diseases in China in the first half of 2012 showed that on average, more than 200 million people suffer from foodborne diseases every year, and one of 6.5 people suffers from foodborne diseases on average. On December 3, the World Health Organization released the world's first comprehensive estimation report on the burden of foodborne diseases at its headquarters in Geneva, saying that almost one in 10 people gets sick every year because of eating contaminated food, resulting in 420000 deaths; Among them, children under the age of five are at extremely high risk, and more than 120000 children die of foodborne diseases every year.

　 Foodborne diseases are the number one enemy of food safety

Maybe everyone will think that diarrhea is nothing. Take some medicine at most. In fact, compared with chemical pollution such as pesticide residues, food contamination by pathogenic microorganisms is the first problem that really affects health.

In the 1980s, there was an epidemic of hepatitis A in Shanghai due to eating raw clams (contaminated by pathogenic microorganisms - liver viruses), and 300000 people were infected. Although hepatitis A generally does not cause death, it is impossible to see a doctor or be hospitalized. So far, this is still a record in the history of foodborne diseases in the world and has not been broken. Is this not enough to show that foodborne diseases are the number one problem?

In 2011, the food contaminated by pathogenic Escherichia coli in Germany attracted worldwide attention. China has also experienced food safety incidents caused by pathogenic Escherichia coli (different from the model in Germany this time). In 2000, 20000 people were poisoned and 177 died in Jiangsu and Anhui. Is this not enough to show that foodborne diseases are our number one enemy?

It is believed that people will inevitably get sick if they eat cereals. It is not surprising that "disease comes from the mouth". Therefore, we did not pay attention to dysentery, typhoid or even cholera (mostly caused by diet), nor did we pay attention to the food poisoning of 50 people in a primary school, or the "upset stomach" of a group of people caused by the food in a restaurant, which seemed not to belong to food safety. The media will not focus on reporting (they will use articles of the size of "tofu blocks" to report food poisoning incidents of 50 people in a primary school, and such "tofu blocks" are not uncommon), nor will they hype online, nor will the public be nervous.

It is no surprise that foodborne diseases are the same as traffic accidents, strokes or heart attacks that happen every day. It is normal to be hospitalized or even die. Everyone was in a calm mood and could not stimulate nervous tension. For the government, the pressure is not great, much less than the "Sudan Red".

　 Common scientific principles can be used to prevent eating sickness

Whether you pay attention or not, eating food contaminated by biological hazards (such as bacteria, viruses, molds, parasites, etc.) has a risk of health damage. Because most pathogens (bacteria, etc.) are infectious, if they survive and do not proliferate after entering the human body (they must withstand the stomach acid environment), they will either invade cells and proliferate in cells to cause damage, and some will continue to cause systemic infection. The body damage will cause a series of defense and repair reactions, and people will get sick.

But it's not bacteria or viruses Or biological toxins (such as aflatoxin), it is inevitable to get sick. Because when biological hazards enter the human body, they sometimes fail to survive and proliferate, but disappear; Or the amount of food eaten is too small to cause damage. In addition, the person is very strong and healthy. If he is not old, weak, sick, young or pregnant, he will not get sick. Therefore, the level of risk is also closely related to the quantity.

When making risk assessment, scientists must consider both qualitative and quantitative issues. The study found that the relationship between the pathogenic risk of biological hazards and the intake "amount" (dose response) is very complex, and the characteristics of pathogens, hosts (animals or people), food, etc., as well as their interactions will have an impact. Emerging food microbiology and predictive microbiology are disciplines specialized in studying such problems. They not only have qualitative assessment (to clarify the nature of microorganisms), but also consider the growth, survival or inactivation of microorganisms, and use mathematical models to make quantitative descriptions.

Microbes are changing, and human life situations are changing, so science must keep pace with the times. As long as new microbial pathogens continue to evolve and be identified, the field of food safety needs to continuously study the relationship between microbial dose and response to make a more scientific and accurate assessment.

As mentioned earlier, the pathogenic mechanism of biological hazards can be divided into two categories, that is, pathogens directly damage the body or toxins produced by pathogens damage the body, and food can become the carrier or transmission medium of these two types of hazards. If the food is not processed or improperly processed, there may be biological hazards (such as pathogenic bacteria). For example, some pathogenic bacteria=microorganisms (such as bacteria and mold) can reproduce in food, and the longer they grow, the more they grow (at the beginning, they grow very fast in the middle stage, and later, because food is consumed, the nutrition they can provide decreases, and the quantity begins to decrease); Some pathogens do not proliferate in food (such as viruses and parasites), but they can exist in large quantities and are infectious (transmitted to food contacts and consumers through appropriate ways). For example, viruses involve 60% - 70% of foodborne infectious diseases.

Microbial growth needs some conditions, such as water, energy, nitrogen sources, vitamins (especially vitamin B) and related cofactors, minerals. If food cannot provide conditions for the growth of microorganisms (such as drying or dehydration), microorganisms cannot grow. For example, controlling the water content in grains such as rice below 14% can effectively prevent mold from growing in them. Of course, the relative humidity must be controlled to ensure that food does not absorb water from the external environment.

Organisms can protect themselves against microbial reproduction in the body. For example, the PH value of most fruits is low, which makes invading microorganisms unbearable (most microorganisms are suitable for growth and survival in the PH value range of 6.5-7.0, while the PH value range of microbial growth in food is wide, 4.0-9.5). Although the PH value of animals is conducive to the growth and survival of microorganisms, such as stomach acid, environment, etc. Other organisms naturally have substances that kill or inhibit microorganisms, such as eugenol in cloves, allicin in garlic, allyl isothiocyanate in mustard, etc.

External factors also affect the growth and survival of microorganisms. For example, heating treatment can eliminate or reduce the potential harm of pathogenic microorganisms in food. The most common methods are pasteurization, sterilization and cooking. In addition, the temperature range of microbial growth is relatively wide. There are microorganisms in air, soil, water, human body, animals and plants, which can become the source of vitamins for contaminated food. In addition, some processed foods are not completely sterile, but only in small quantities.

Therefore, food should be stored at a suitable temperature to control the growth of microorganisms (temperature requirements vary depending on the type of microorganisms, for example, the United States requires that eggs be transported and stored below 5&# 8451; all the time).

　　 How to control food contamination by pathogenic microorganisms?

There are three aspects to control food contamination by pathogenic microorganisms. First, manage environmental sanitation, such as feces, garbage, sewage, etc; Second, manage the sanitary conditions and processing technology of the enterprise. Food production, storage, transportation, sales and catering preparation must comply with the operating procedures of food hygiene; Third, various tests are also a regulatory means and deterrent tool.

From the operational level, food production should be strictly in accordance with the requirements of Good Practice (GMP), Hazard Analysis and Critical Control Point (HACCP); In family life, scientific and hygienic operation specifications should also be observed.

Finally, we should know that microorganisms have strong adaptability. Many bacteria can survive and reproduce under extreme conditions (such as low temperature or high temperature, high salt, low PH value, etc.), and can survive against the killing effect (such as the killing of gastric acid environment, immune system, etc.) caused by biological self-protection. The improvement of food processing technology, agricultural technology and the use of antibiotics will also change the microbial flora. Take Escherichia coli as an example. Human beings have struggled with it for two centuries. They are also constantly changing in the struggle, and their drug resistance is getting higher and higher. In 2011, the pathogenic strains of German Escherichia coli can resist seven or eight kinds of antibiotics. Human beings still have a long way to go if they want to keep away from pathogenic bacteria based on science and ensure food safety.

Article debut Food and Nutrition Information Exchange Center If you need to reprint, please contact the Food and Nutrition Information Exchange Center.

——Chen Junshi, researcher of National Food Safety Risk Assessment Center, academician of Chinese Academy of Engineering.

Recently, Huishan Dairy has been pushed to the forefront of food safety. Experts from the National Food Safety Risk Assessment Center made a scientific assessment and interpretation from the perspective of safety, and proved that the detected thiocyanate level is within the safe range, so consumers need not worry.

On the evening of the 29th, the Food and Drug Administration of Hebei Province also announced that, based on the results of emergency sampling inspection, experts were again organized to study and judge that 15.2 The detection value of mg/kg is of low health risk to consumers, so it is decided to withdraw the food sales safety warning issued on September 24.

So far, the truth of this event has been clear, that is, it is normal to detect thiocyanates in milk, because there are already thiocyanates in milk; There is no need to worry about the level of detection this time. At the same time, the so-called "exceeding standard" of sodium thiocyanate in milk is a myth, because the national food safety standards in China do not set the limit value of thiocyanate in milk.

From this Oolong incident, I think we should at least get three inspirations:

First, under the current specific public opinion in China, it is necessary to strengthen the expert interpretation of various "food safety incidents" reported by the media in a timely manner, because the daily science popularization cannot cover all kinds of difficult to estimate situations, such as thiocyanate in milk this time. To achieve this, in addition to the initiative of experts themselves and third-party information exchange institutions based on experts, the support and guidance of the government is very important.

Second, when releasing food safety information, government regulatory authorities should strictly comply with the provisions of the new food safety law, for example, in the new food safety law, Article 23 stipulates that "the food and drug supervision and administration departments of the people's governments at or above the county level... shall, in accordance with the principles of science, objectivity, timeliness and openness,..., exchange and communicate on food safety risk assessment information and food safety supervision and administration information", and specifically "in accordance with the principles of science, objectivity, timeliness and openness"; Article 118 stipulates that "food safety information shall be published accurately and timely, and necessary explanations shall be given to avoid misleading consumers and public opinion". The information released this time involves sensitive dairy issues, so we should be cautious in particular, and never make management decisions.

Third, risk management should be based on science. Risk management decisions should be based on science, which is also a highlight of the new food safety law. If the Hebei Food and Drug Administration communicates with relevant departments and authoritative experts in advance before releasing the food safety warning information, it will not cause such a black dragon, nor will it cause unnecessary panic to consumers. Through this event, it also reminds the government regulatory authorities to take science as the criterion when making risk management decisions in the future.

Extended reading:

Chen Junshi The Position of Risk Exchange in the New Food Safety Law

Liu Zhaoping, Yong Ling What's the matter of detecting sodium thiocyanate in milk?

Recently, the National Health and Family Planning Commission publicly solicited opinions on the proposed approval of gold foil for liquor, with a maximum use of 0.02 grams per kilogram. One day, I received more than ten calls from the media, all asking me about adding gold foil to liquor.

My unified answer is: please see the website of Kexin Food and Nutrition Information Exchange Center（ www.chinafic.org ）Shangruan Guangfeng's article Is there a problem with adding gold foil to liquor. I agree with the content and views of this article.

In short, first of all, the addition of gold foil to food is not a wonder in the world, but has long existed in other countries, but has never attracted such attention.

Secondly, adding gold foil to food has no safety problem.

Third, as for whether it is necessary to add gold foil in liquor, different people have different opinions. The proponents believe that adding gold foil can increase the sensory properties of liquor, just like adding colorants (pigments) to candy. Opponents believe that liquor is liquor, and there is no need to change the original properties. Whether the Health and Family Planning Commission will finally approve gold foil as an additive for liquor, I think the key lies in the "process necessity". During the formulation of food safety standards, public opinions were solicited, which fully reflected the transparency. Whether gold foil can be approved as liquor additive or not, it is undoubtedly successful in mobilizing the masses to participate in the national standard formulation process.