Thermos cup is a must-have in winter, how can you buy a safe one?

Now that the weather is getting colder, many people are using thermos cups. Many people who don't use thermos cups yet are also preparing to buy one. But there are many kinds of thermos cups on the market, with high and low prices and uneven quality. So how do you choose?

Appearance is the basic "duty" of a thermos cup, but when you hold it in your hand, you will find that the material is more important than appearance. Most thermos cups are made of stainless steel, which is resistant to high temperatures and has good heat preservation performance. Stainless steel materials are usually divided into three types, "codes" are 201, 304 and 316.

201 stainless steel is the best at camouflage. Most of the unqualified thermos cups in the news use 201 stainless steel as the liner of the thermos cup. 201 stainless steel has a high manganese content and poor corrosion resistance. If it is used as the liner of a thermos cup, long-term storage of acidic substances may cause manganese precipitation. Metallic manganese is an essential trace element for the human body, but excessive intake of manganese can harm the body, especially the nervous system.

304 stainless steel is the most commonly used stainless steel. When stainless steel comes into contact with food, its main safety hazard is the migration of heavy metals. Therefore, the stainless steel in contact with food must be food grade. The most commonly used food grade stainless steel is 304 stainless steel with good corrosion resistance. In order to be named 304, it needs to contain 18% chromium and 8% nickel to be justified. 304 stainless steel is relatively acid-resistant, but it is still prone to pitting corrosion when encountering substances containing chloride ions, such as salt solutions.

316 stainless steel, a more advanced version. Compared with 304 stainless steel, it is more prone to pitting corrosion when encountering substances containing chloride ions. 316 stainless steel is an advanced version: it adds metal molybdenum to 304 stainless steel, which has better corrosion resistance and is more "tough". Unfortunately, 316 stainless steel is expensive and is mostly used in high-tech fields such as medical and chemical industries.

When buying a thermos cup, pay attention to the following points:

First, "look". The stainless steel body of the thermos cup must comply with the relevant requirements of GB 4806.9-2016 "National Food Safety Standard Metal Materials and Products for Food Contact". Check the material composition and type marked to see if they are qualified. Do not just mark "high-grade stainless steel" or "high-quality stainless steel" and other simple information; the sealing lid of the thermos cup should use safe and heat-resistant PP material.

Second, "touch". The outer and inner liner of the thermos bottle should be polished evenly, without scratches, bumps or burrs, and the welding joints should be smooth.

3. Smell. The cup should have no irritating odor.

Four "tests". Pour boiling water into the cup and tighten the lid. If there is no obvious temperature rise when holding it with your hand after 2-3 minutes, it means that the insulation effect of the thermos cup is good. Then turn the cup upside down for 4-5 minutes to observe whether there is leakage. If there is no leakage, it means that the sealing performance of the cup is good.

Friends, have you learned it? Try it out quickly. I hope you can buy a good-looking and useful thermos cup!

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Reference sources: Science Popularization China, Capital Education, Healthy China