Compared with stainless steel pots, iron pots, ceramic pots, etc., aluminum pots have the advantages of being cheap, lightweight, fast in heat conduction, rust-free and durable, and can be reshaped if deformed.

Text | Popular Science

Almost everyone has, or has had, an aluminum pot at home.

Compared with stainless steel pots , iron pots, ceramic pots, etc., aluminum pots have the advantages of being cheap, lightweight, fast in heat conduction, rust-free and durable, and can be reshaped even if they are deformed.

However, according to a 2012 food safety risk assessment , about 32.5% of my country's residents have a weekly dietary aluminum intake that exceeds safety standards.

The ways in which aluminum enters the human body include water, food, food additives and cooking utensils, etc. Therefore, people have turned their suspicious eyes to the aluminum pots used every day.

So, are aluminum pots really the culprit of Chinese people’s excessive aluminum consumption? Why don’t we ban aluminum pans? What are the dangers of excessive aluminum intake?

More than 400 million Chinese people have excessive aluminum intake, and the number of children has reached 100 million. What are the dangers?

At the 2012 National Food Safety Risk Assessment Seminar, Chinese Academy of Engineering academician and nutrition and food safety expert Chen Junshi published a survey report. The report showed:

About 32.5% of residents in China have dietary aluminum intake Exceeding safety standards, with children aged 4-6 accounting for the highest proportion, reaching 42.6%.

This means that more than 400 million people in our country have excessive aluminum intake, and the number of children has almost reached 100 million.

Generally speaking, the aluminum content in the normal human body is between 45-150 mg. However, the 14 essential trace elements announced by the WHO in 1973 did not include aluminum. Instead, it was listed as in 1989. Food pollutants have low toxicity and are harmful to the human body.

After a person ingests aluminum, only 15% at most can be excreted from the body. Most of it is accumulated in the body and combines with a variety of proteins and enzymes to produce aluminum phosphate, which affects intestinal absorption function, calcium ion homeostasis and other activities. element, which is toxic to the liver, kidneys, bones, and nerves.

People who consume excessive amounts of aluminum will suffer from confusion of thinking and consciousness, failure of visual and motor coordination, memory loss, and metabolic dysfunction, which may affect the central nervous system, digestive system, hematopoietic system, and immune function It has an impact on fetal growth and children's intellectual development.

In 1965, the American neuroanatomy scientist Dr. Igor Krazo discovered in experiments related to rabbits ingesting aluminum phosphate:

The protein fiber state in the brains of rabbits is very similar to that of patients with Alzheimer's disease. Therefore, excessive aluminum is also It is suspected to be one of the causes of Alzheimer's disease. Although it has yet to be confirmed, there is no doubt that excessive aluminum can cause damage to nerves.

So, why do these 400 million people have excessive aluminum levels? Could it be the aluminum cookware? To solve this problem, we must first understand the making and classification of aluminum pots.

Aluminum pots

Most of the aluminum pots on the market are made of aluminum alloy. The pot body is made of aluminum, but the bottom is made of stainless steel .

There are two main ways of processing and forming aluminum alloy cookware:

• Deformed aluminum alloy sheet pressing and forming:

including deep drawing and spinning. The most commonly used aluminum alloy is aluminum-manganese alloy (3XXX), including 3003 Or 3103A, which has better corrosion resistance and is relatively stable under neutral conditions.

• Cast aluminum alloy Casting molding:

This includes die casting and pouring. Die casting is the most common ZL102 alloy with a silicon content of 10-13%. Casting is generally . The silicon element is less than 5%, and there is no definite brand.

This type of pot has a relatively high silicon content, poor corrosion resistance, and a relatively high impurity content. It is prone to white rust when exposed.

Aluminum cookware mainly includes bare aluminum pots, coated aluminum pots, anodized aluminum pots and cast aluminum aluminum pots, etc. Countries are not clear about the migration standards of aluminum elements, so many of them on the European market are aluminum-coated pots. However, our country has specifically stated that:

aluminum alloys not covered with organic coatings, copper alloys , metal coatings, iron-based materials, low carbon steel , etc. cannot be in direct contact with acidic foods.

This is because many metal elements often precipitate due to high temperature and high pressure during use, and aluminum is no exception.

So, will aluminum pots be the main reason why Chinese people’s aluminum intake exceeds the standard?

Are aluminum pots the main culprit for Chinese people’s excessive aluminum standards?

The WHO clearly stipulates that the safe standard for aluminum intake for a person weighing 1 kg is 2 mg per week , and for a person weighing 120 catties, it is 120 mg per week.

However, experimental data shows that people who use aluminum cookware every day have an aluminum intake of about 3.5mg, and the intake of new aluminum cookware is 2 times higher than usual!

Some scientists have done experiments, and the results show:

The aluminum content in rice cooked in an aluminum pot is 3.85-10.93mg/kg; when cooking sweet and sour pork ribs in an aluminum pot, the aluminum content is 6.03-16.48mg/kg. The aluminum content in the soup is 8.89-16.25mg/kg;

use aluminum cooking utensils to fry food, the aluminum content in the cooking oil increases from the original 6μg/g to 10-20μg/g; soak in 4% acetic acid for 2 hours. The aluminum dissolved out is 5.2mg/kg at 20℃ and 2.14mg/kg at 60℃.

This shows that cooking acid-base or salt-containing foods in aluminum pots will produce more aluminum. There is also a clear correlation between the length of time and temperature of cooking and storage and the precipitation of aluminum.

In a survey on the correlation between the use of aluminum cookware and cardiovascular disease among 544 permanent residents in Beijing, it was found:

The risk of cardiovascular disease is 3-4 higher when using aluminum cookware than when not using aluminum cookware. times, with the male correlation coefficient being 3.91 and the female correlation coefficient being 2.72.

This shows that using aluminum cookware is indeed harmful, but this does not mean that all aluminum comes from pots.

Aluminum is insoluble in water. As long as it comes into contact with air, it will form alumina . Therefore, the stability of aluminum pots is actually very high. has a melting point as high as 1400 degrees and will not be toxic. Under ordinary cooking conditions, this layer The aluminum oxide film will prevent aluminum from dissolving into food, just like the iron pot that replenishes iron has a minimal effect, so we cannot use aluminum pots.

In fact, the aluminum content in many foods is actually higher than that precipitated from aluminum pots.

For example, the aluminum content of fried dough sticks can be as high as 860mg/kg, the aluminum content of wheat flour is 10-20ppm, and the aluminum content of dry tea leaves is generally 500-2000ppm.

Data shows that people’s aluminum intake from flour-based foods accounts for up to 44%, mainly because of the aluminum-containing puffing agents.

The highest aluminum content in puffed food on the market exceeds the national standard by nearly 9 times. This is why a large proportion of children exceed the standard.

What should you pay attention to when using aluminum pots?

Although aluminum is insoluble in water, it is an amphoteric metal and can react with acids and alkalis. You should be more careful when using it and do not store it for a long time or at high temperatures.

• It is not suitable to hold high-protein items such as eggs or milk:

Animal protein and plant protein are easy to combine with aluminum, makes the egg white turn gray and the egg yolk turns green, produces hydroxide , eat it The harm to the body is even greater.

• It is not advisable to heat acidic and alkaline foods:

Acidic and alkaline foods will destroy the oxide film on the surface of the aluminum pot, cause aluminum to precipitate, and even produce other chemical harmful substances that are harmful to the body.

• Do not boil water directly when using it for the first time:

Directly boiling water in a new aluminum pot will make the pot black. It is best to fill the small concave holes on the pot wall with oil first to increase the corrosion resistance.

At present, my country has clearly stipulated that acid sodium aluminum phosphate , sodium aluminosilicate and octenyl aluminum succinate starch cannot be used as food additives, and aluminum-containing leavening agents cannot be added.

However, in order to save costs, some unscrupulous merchants still take risks and continue to use them. Many 5 and 1 yuan snacks mostly fall into this category. You should eat less of these harmful foods and use more when using aluminum cookware. Pay attention to to avoid accidentally hurting yourself and your family.