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Do you like chocolate? Is it dark chocolate, white chocolate or milk chocolate? In fact, each school has different supporters, but let me change the question… Which part of chocolate or what type of chocolate do you like to eat?

I think most people’s answer is solid, crunchy taste, right? The fastest way to taste this kind of chocolate is to aim at the corners of the chocolate bricks.

But do you know why the chocolate on the corners is so crispy? Scientists may have the answer!

Many people seem to like to eat the corners of chocolate, because it is more crispy~ Picture/Pexels

What you need to know about chocolate is…

First, letLet’s first understand what ingredients are in chocolate. Chocolate is made of cocoa powder, cocoa butter, sugar and other ingredients mixed with each other. Some of the interesting chemical ingredients are introduced here:

  1. Theobromine: A kind of alkaloid, similar in structure to caffeine, is regarded as the same series of chemical substances, but in terms of toxicity (actually the property that makes you high) is weaker than caffeine. Chocolate is the food that contains the most theobromine. And because a piece of chocolate has both ingredients, the people who eat it will be so happy.
  2. Antioxidants: Cocoa beans contain antioxidants such as green tea phenol and gallic acid, but in the process of making cocoa beans into chocolate, many of these substances will be removed, leaving a small amount of residue. Many chocolate lovers say that the antioxidants in chocolate can delay cell aging, but it is difficult for us to confirm whether such trace ingredients are effective.
  3. Phenylethylamine: Some people say why chocolate is so popular on Valentine’s Day because it contains a lot of phenethylamine… a neurotransmitter that releases dopamine in the brain. It is also the main ingredient of stimulants, aphrodisiacs, and antidepressants, but It is a pity that the phenethylamine in the chocolate is absorbed by our body before it enters the head.

However, none of the above is the focus of research on the taste of chocolate. The most important substance that makes chocolate taste delicious is actually triglycerides, which is the crystalline structure of cocoa butter (fat).

Cocoa Butter-Wikipedia, the free encyclopedia
Cocoa butter in a single piece and separate. Picture/wikimedia

Cocoa butter that makes chocolate charming

Chocolate will have different tastes because of the different melting and coagulation processes of cocoa butter, because the fat may show a variety of different structures at different melting points, but the cocoa butter of chocolate is not the same as ordinary fat.

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Cocoa butter is one of the few fats composed of only a few different triglycerides, of which up to 60% are saturated fatty acids and 30-40% are monounsaturated fatty acids.We know that because the carbon chains of saturated fatty acids do not have double bonds, they can be arranged closely and orderly to form a stable structure and a higher melting point. Therefore, animal fats with a high proportion of saturated fatty acids, such as tallow and lard, will become solid at room temperature. On the contrary, unsaturated fatty acids have one or more double bonds in the carbon-carbon connection, which are prone to bend and cannot be arranged neatly. Therefore, the structure is not as stable as saturated fatty acids, and the melting point is relatively low. Vegetable oils that are liquid at room temperature are examples of unsaturated fatty acids.

The ratio of saturated fatty acids and monounsaturated fatty acids in cocoa butter makes the melting point relatively constant, resulting in chocolate without the feeling of particles when it melts in the mouth.Even so, cocoa butter still has several forms of crystals, and the melting point distribution ranges from 17 to 37 °C. The ideal target for making chocolate is the melting point of 33.8 °C.Type 5 β crystal

CHOCOLATE TEMPERING - Gastronomic Research Center Gastro_IC
Very detailed melting point and taste of different chocolate crystals, of which type 5 is the best condition. Picture/compoundchem

The taste that melts in the mouth is derived from the arrangement of crystals

Most people don’t care about the arrangement of molecules when eating chocolate, but molecular scientists who like to eat will disassemble the chocolate and take it under the instrument to find out. In the recent scientific journal published by the American Chemical SocietyCrystal Growth & DesignIn “, a group of researchers who like chocolate found that when you shape the chocolate in the mold, the chocolate crystals on the side closer to the mold are arranged more neatly than the side that is in contact with the air, and are usually more popular.

The arrangement of chocolate crystals greatly affects the taste, so there is an important step that must not be ignored when making chocolate-temperature adjustment.

When dessert factories make chocolate bricks, they will melt at the ideal temperature (That is 33.8°C above, which is quite close to human body temperature 36°C) chocolate liquid is poured into the mold to cool down. At this time, there is a very important step called“Temper”In simple terms, tempering is a repeated process of melting and coagulating chocolate to stabilize the chocolate. Due to the crystallization characteristics of cocoa butter,The chocolate block that has been properly tempered will form a complete and neat crystal structure, with a smooth surface, a hard and brittle taste, and it melts in the mouth and is popular.

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After the chocolate craftsman’s temperature adjustment, the messy structure in a piece of original chocolate will be melted, but I want to leave the model raw in these chocolate crystals, that is, β crystals. When the remaining chocolate solidifies, The 5th type β crystal will be used as the template. The result is that the whole piece of chocolate is a delicious ideal crystal structure, hard and bright, and sometimes even finished chocolate blocks are added to make the whole piece of chocolate faster and perfect. , Grease is arranged in an orderly manner.

Use an infrared spectrometer to measure the crystal structure of cocoa butter!

The above are the parts that we already knew when making chocolate, but now we have to make something different! A group of researchers wanted to know if the chocolate on the side in contact with the air tastes worse than the chocolate on the mold during the cooling process. Which part is more delicious?

In order to understand this matter, the researchers analyzed the molecular composition of chocolate fat in three different locations. Using Fourier Infrared Spectroscopy and attenuated total reflection sampling, they foundThe chocolate molecules on the side contacting the mold are arranged quite neatly, and the fatty acid chains are regularly distributed in this areaOn the contrary, the side close to the air is arranged chaotically, and there is no fatty acid chain; and the chocolate in the center is just between the two.

Different parts of the chocolate have different textures due to the presence or absence of contact with the mold and the arrangement of the crystals. Photo/Pexels

The taste of commercially available chocolate is not uniform

This result is likely to be related to the difference in heat conduction between the mold and the air, causing the chocolate close to the mold to cool faster and have more time to arrange the crystals. The mold also controls the alignment of the crystals to a certain extent to be more uniform and orderly. , And this is the key to making chocolate delicious. Because of this,In fact, a whole piece of chocolate is more uneven than everyone thinks. It is normal for different parts of the chocolate to have different tastes.Researchers also hope that through this research, chocolate manufacturers may be able to come up with different methods to make chocolates that suit everyone’s taste more accurately and faster… If there is a way to make a whole piece of chocolate crispy and smooth, How good is that?

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So if you think that the chocolate near the corners is the most delicious part, it means that your tongue and mouth resonate with the chemical crystal arrangement, and you know that next time you grab chocolate with people around you, you should aim for that part. , And maybe it can be a trick to chase chemists.

The next time I eat chocolate, I have more chemistry knowledge to share. Maybe it is a trick available to follow the chemistry department? Photo/chemistryworld.com

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