With the rise of environmental awareness, more and more people are used to carrying thermos cups with them when they go out! However, recently, there has been a widespread rumor on the Internet that “a thermos cup cannot be used to make tea, contain coffee, juice, or milk. Otherwise, the stainless steel on the inner wall of the thermos cup may be corroded, resulting in the release of heavy metals and affecting human health.” this has caused panic among netizens. Is the above statement true or false? Listen to the toxicologist!
how much do you know about the structure of thermos cups? Vacuum + corrosion resistant stainless steel to the destination
In response to the doubts of the outside world, Dr. Yang Zhenchang, director of the Department of clinical toxicology and occupational medicine at Taipei Veterans General Hospital, said that before discussing whether the above drinks in thermos cups release toxins, we might as well take a look at the main components of thermos cups.
Generally speaking, a regular thermos cup is mainly made of stainless steel inner and outer walls, coupled with a double-layer vacuum pumping structure, in order to truly play its due heat preservation function. The reason why stainless steel is called “stainless” is mainly because a certain amount of “chromium” must be added to the stainless steel during the manufacturing process. When chromium comes into contact with air and oxygen in the environment, it will form a special “chromium oxide” film to prevent corrosion and release of heavy metals.
Therefore, compared with ordinary steel, stainless steel has relatively high corrosion resistance and oxidation resistance. It is also because stainless steel has the advantages of corrosion resistance and oxidation resistance that it is widely used in pots and pans in daily necessities, naturally including the inner and outer walls of thermos cups.
put these drinks in the thermos? Doctors’ opinions are open
After understanding the structure of the thermos cup, we can then discuss one by one whether the thermos cup can only hold water, as is rumored on the Internet, tea, coffee, juice, milk and other drinks are not suitable? Let Dr. Yang Zhenchang explain one by one.
Q1 / tea and coffee should not be put in the thermos cup, otherwise the tannic acid contained in it will lead to oxidation and deterioration of stainless steel, and even release heavy metals in the thermos cup
In this regard, Dr. Yang Zhenchang pointed out that during the brewing process of tea and coffee, tannic acid components are indeed gradually released as the placing and brewing time lengthen, which in turn affects their flavor.
However, the influence of tannic acid is only that. In fact, tannic acid, which has the word “acid” in its name and belongs to polyphenols, is actually a kind of nitrogen-containing alkaline substance with significant physiological effect in plant tissues, not an acid component with corrosive effect as recognized by the outside world.
Therefore, it is naturally impossible to cause acid corrosion of stainless steel, not to mention that the corrosion resistance of stainless steel with good quality and no wear on its surface is quite high. If it is not for high concentration of strong acid, it is impossible to cause its deterioration. In fact, what the public should be worried about is whether there are doubts about the excessive application of pesticides and the presence of heavy metals in the soil during the planting process of tea.
Q2 / decocted traditional Chinese medicine contains a lot of acidic substances, which is easy to cause corrosion of the stainless steel inner wall of the thermos cup, and then affect the health of drinkers
Dr. Yang Zhenchang stressed that the first thing to clarify is that not all Chinese medicines contain acidic substances. And as explained before, stainless steel with good quality and no wear on its surface has high corrosion resistance; If it is not for high concentration of strong acid, it is impossible for it to suffer from acid corrosion, let alone the Chinese herbal soup that the human body can drink. In fact, the most common problems of Chinese medicine in thermos cups are that the color is easy to stick to, the smell remains, and it is difficult to clean. There are no health concerns.
Q3 / it is not recommended to put juice in the thermos cup, especially acidic fruits such as lemon and orange, to prevent the inner wall from being corroded
As mentioned above, as long as it is not a high concentration of strong acid, it will not damage stainless steel. Therefore, even concentrated fruit juice and drinks are safe to put in a thermos cup. The only thing to note is that because the juice is sweet and rich in carbohydrates, it is recommended to drink it fresh within 30 minutes after opening; Or put it into the refrigerator for storage as soon as possible, so as to prevent a large number of microorganisms and bacteria from growing and deteriorating.
Q4 / it is not recommended to put hot milk in the thermos cup, so as not to cause microorganisms and bacteria to multiply rapidly and corrupt under the heat preservation state
Dr. Yang Chen Chang points out that in fact, whether it’s hot milk or cold milk, nutritious dairy products have always been a favorite food for bacteria and microorganisms. Once the storage environment temperature is between 20 ° C and 30 ° C (deicing and cooling), it is easy to lead to deterioration and gastroenteritis after drinking. Therefore, it is recommended that whether it is hot milk or cold milk, it is better to brew and pour it out as soon as possible, which is more secure.
Q5 / carbonated drinks in thermos cups are even worse, for fear that the inner wall of the brew will corrode and harm health
As for carbonated drinks such as soda and cola, is it appropriate to put them in a thermos? In fact, the weak acid of carbonated drinks will not harm stainless steel. However, it should be reminded that because of the existence of bubbles in carbonated drinks, it is recommended that when pouring into the thermos cup, it is better not to fill it up and leave a certain gap to avoid a large number of bubbles when opening it.
extend the service life! The thermos cup is so clean that it can be stored safely.
In addition to explaining whether the above-mentioned common drinks can be put into thermos cups, Dr. Yang Zhenchang reminded consumers that the tan dirt visible on thermos cups is mostly caused by tannic acid and food pigment residues, not so-called oxidation deterioration of stainless steel; Therefore, as long as you soak and rinse with sponge, baking soda, white vinegar and water, it can be easily removed without excessive worry.
Finally, Dr. Yang Zhenchang also reminded that in order to prevent the generation of peculiar smell or stains and extend the service life of the thermos cup, in addition to avoiding collisions and heavy falls as far as possible, so as not to affect its heat preservation function; If you can properly clean the thermos cup after each use, so that the thermos cup can be fully air dried, it can be used for a long time and healthily.
Leave a Reply