Insulation cups make tea with heavy metals?Stainless steel is not so vulnerable

Insulation cups make tea with heavy metals?Stainless steel is not so vulnerable
“When people reach middle age, there are three treasures, wolfberry and jujube thermos.”After the beginning of winter, the thermos cup has become the standard for many middle-aged people, and even some young people in the Buddhist department have picked up the thermos cup.However, the rumors about brewing tea in stainless steel thermos cups and lycium barbarum will cause the dissolution of heavy metals and cause chronic poisoning, which makes many people uneasy when using thermos cups.Is it really dangerous to drink hot tea every day?  In accordance with the regulations, tea cups will not be poisoned. The reason is that tea cups will produce tea stains. Many people worry that tea stains will adhere to the inner wall of stainless steel for a long time, which will cause corrosion of stainless steelDissolve heavy metals in the body, causing chronic poisoning.After the tea was shot, wolfberry and carbonated drinks were also added to the black list of stainless steel insulation cups.  In progress, Professor Ren Yibin, School of Materials Science and Engineering, Shenyang University of Science and Technology said with a smile: Stainless steel is not so “flammable”. Only steels containing more than 13% chromium can afford the name of stainless steel.To ensure the formation of a passivation film on the surface of stainless steel to protect the stainless steel substrate.In GB9684-2011 national food safety standards, there are clear requirements for stainless steel materials for tableware.In general,南京桑拿网 in addition to chromium, stainless steel is intentionally added with nickel, molybdenum, manganese, copper, nitrogen, vanadium and other alloying elements to improve the mechanical properties and corrosion resistance of stainless steel, but lead, cadmium and arsenic are harmful to stainless steel.The impurity elements are strictly restricted.  ”However, stainless steel is not‘ the diamond is not bad ‘. When it encounters corrosive environments such as acid, alkali, and salt, corrosion may still occur and cause some alloy elements to dissolve.”Introduction of Ren Yibin, therefore, the national standard GB9684-2011 also requires the elution limits of lead, chromium, nickel, cadmium and arsenic. The test conditions are harsh conditions that are almost impossible to meet for the time being.Boil in acetic acid for 30 minutes, and analyze the metal content in the room after 24 hours in the room. The dissolution of various alloy elements in stainless steel vessels is less than 0.5 mg / dm2.  Wang Hao, an associate professor in the School of Food Science and Technology of Tianjin University of Science and Technology, said that a phrase often used in the field of food science is “cannot say toxicity without putting aside doses.”Not to mention tea stains, soaking for several days in a row, for stainless steel cups that meet the standards, there is no need to worry about the dissolution of alloying elements.Even if a trace amount of alloying elements is corroded and dissolved, the chromium, nickel, manganese, molybdenum and other alloying elements in the stainless steel for tableware are essential trace elements for our human body, which will not affect our health.  Choosing a thermos cup by a magnet is not reliable. “Although stainless steel thermos cups are not as fragile as we think, when consumers choose a thermos cup, they must choose a stainless steel thermos cup that meets quality standards.”Ren Yibin reminded everyone.  On the e-commerce platform, click on the specifications and packaging of some well-known brands of thermos cups. The materials inside will be marked with 316, 304 stainless steel or other types of stainless steel. This series of numbers makes consumers a little puzzled.Other consumers will distinguish the quality of the material based on whether stainless steel is magnetic.  According to Ren Yibin, according to the national standard GB9684, the stainless steel materials for tableware include austenitic stainless steel, austenitic-ferritic duplex stainless steel, and ferritic stainless steel.The biggest difference between these three stainless steels is that they have the same name, and one of the performance differences is magnetic.Among them, only austenitic stainless steel is non-magnetic, and the other two are commonly called “stainless iron” by the folk.The price of austenitic stainless steel is generally higher than the latter two.In addition, there are many types of austenitic stainless steels, and the price differences are relatively long.Among them, the more expensive 304 and 316 alloy elements are iron, chromium, and nickel, but the proportions of chromium and nickel are different.Among them, nickel is a relatively expensive alloying element, and its main role is to ensure the stability of the austenite structure and properties of stainless steel.In addition, there are low-nickel (nickel-saving) manganese-containing austenitic stainless steels. Since manganese and nitrogen are used instead of some nickel to stabilize the austenite structure, the price is relatively cheap, but performance and safety are not bad.  ”As long as these types of stainless steels meet the quality standards, their use safety is basically not a problem.And from the manufacturers and brands, the stainless steel grade or chemical composition will be marked on the label.”Ren Yibin reminded consumers that those who are allergic to metal elements must check the corresponding stainless steel composition on the Internet according to the marked stainless steel grades.For example, patients with nickel allergies should not choose 304 stainless steel products, and patients with manganese allergies should not choose stainless steel products containing low nickel and manganese.  Stainless steel thermos cups make tea taste bad “Although stainless steel thermos cups are not poisonous, a long high temperature environment may affect the nutrition and taste of some foods.Wang Hao said that if you can make tea in a thermos cup, it will affect the taste of the tea.That is because tea contains tea polyphenols, tannins, aromatic substances, amino acids, and multivitamins. When boiling water in a teapot or ordinary glass, the active substances and flavor substances in the tea will soonDissolve, the tea is overflowing.The use of stainless steel insulation cups will continue to insulate the environment, which is equivalent to continuously cooking tea with high-temperature water. Continuous high temperatures cause the tea polyphenols to dissolve extremely well, and the active substances and aromatic substances are destroyed by heat, leading to tea soupThe quality will also be destroyed, the tea soup will be thick, the color will be dark, and the taste will be bitter.  For high protein drinks such as soy milk and milk, it is not recommended to use stainless steel thermos cups.This is because bacteria multiply in large numbers at the right temperature. For food storage, it can only be sterilized or stored at low temperature (to delay spoilage).Residual nutrients such as soybean milk and milk are continuously stored at the right temperature, and microorganisms will multiply.Soymilk and milk will soon become rancid and spoiled once they grow bacteria. They will appear flocculent in shape and appear tofu brain-like. After eating, they will cause diarrhea.Therefore, it is best to drink this kind of beverage within 3 hours.If you want to keep soy milk and milk for a longer time, you must first soak the thermos cup with boiling water and wash it to kill the bacteria that may be present, and then pour the soy milk and milk.  For the middle-aged people’s favorite wolfberry, Wang Hao does not recommend the continuous brewing of the insulated cup: “Although brewing of wolfberry with a stainless steel insulated cup does not produce substances that are harmful to health,If it is 80 kilowatts, and the wolfberry is continuously soaked in high temperature water, many vitamins and other nutrients in the wolfberry will be lost.And soaking the water with wolfberry, the efficacy of which is not fully realized.Due to the influence of water temperature, soaking time and other factors, only some medicinal minerals in wolfberry are released into water or soup.”

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