Recently, a video was circulated on the Internet, in which a female consumer said that a brand of fans can actually be lit with a lighter, and the more it burns the more thriving the sound of chopping and popping, the woman said: ? These fans burn so fast? They are made of plastic? The woman said: "These fans burn so fast? Stick to the pen to shake can not be shaken off, a good fan of a pinch on the break, how to pinch this pinch constantly?

This? fans are made of plastic? The video got a lot of retweets, many netizens said ? Never dare to eat fans again?

So what is the truth of the matter?

Do real fans burn?

Normal vermicelli contain a lot of starch and proteins, and these organic substances can be burned in the air. Therefore, we can't differentiate between vermicelli and plastic solely on the basis of whether they can burn or not. If you judge by combustion alone, then human hair is also combustible, is human hair also made of plastic?

Of course, from a practical point of view, there are a lot of vermicelli producers all over the country, and the vermicelli produced are very different, so we can't rule out the possibility that some chemical additives may be used in the vermicelli produced by individual companies for the purpose of coloring and so on.

On the whole, it's normal for vermicelli to burn.

What's the best way to tell starch from plastic?

A more complex approach but one with good accuracy is of course to rely on scientific instruments? For example, liquid chromatography and mass spectrometry instruments.

Such scientific instruments are too expensive for the common man.

Tadpole can introduce you to another simple scientific approach: colorimetric reaction.

Identifying starch in vermicelli with color reaction

As mentioned before, vermicelli contains a lot of starch, which is polymerized from glucose molecules. To put it plainly, ? There is sugar in vermicelli, and there is no sugar in plastic?

Here comes the key point: there are two types of starch: straight chain starch and branched chain starch. Straight-chain starch is blue when exposed to iodine, and branched-chain starch is purplish red when exposed to iodine.

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Therefore, in life, we only need to soak the fans in water, and then add some family medicine box used to disinfect the iodine (the color is brown), if the color from brown to blue or purple-red, it means that you have this fan contains starch, and certainly can not be all made of plastic. Because plastic is mainly polyethylene or polypropylene, these plastics themselves do not contain starch, it is also impossible to appear this color reaction.

Identifying proteins in vermicelli with the color reaction

We know that the color reaction is a convenient test method that relies on the naked eye (which may be biased), so we should verify it in many ways.

Normal vermicelli contains not only starch but also protein. And there is no protein in plastic, so we can distinguish them by detecting protein.

We can put a small section of fans (or plastic) first add sodium hydroxide solution (2mL), shaking well to create an alkaline reaction environment, and then add 3 to 4 drops of copper sulfate solution (blue), and then shaking well to observe the phenomenon: if it is a fan, the solution will turn purple, which is because the fans contain proteins caused by the fans; and if it is a plastic, it will keep the blue color will not change. If you can distinguish between blue and purple, you can tell the difference between plastic and vermicelli.

Of course, this method requires some chemical reagents, which is not very convenient in life, but it is a general method to detect protein. It is useful for us to screen fans and plastic.

Summary

In daily life, if there is no iodine at home, there is no sodium hydroxide and sulfuric acid, these chemical reagents, the above mentioned color reaction is not good to implement. Then you can observe by burning and smell the way to identify: fans after burning and no pungent odor, while the plastic will produce oil droplets after burning and pungent odor. If there is a pungent odor after burning a certain type of fan, it is recommended not to eat.

In short, the fan is organic, in general it is relatively dry, surely can be burned, about ? Fans can be ignited is plastic? The logic of the claim is flawed and not worth believing. The reality is more complex, can not rely solely on the burning to conclude that the fans are plastic. For the regular manufacturers of fans, you can rest assured to buy.

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Author: Tadpole Jun