Chocolate
Kamal Lodaya, The Institute of Mathematical Sciences, Chennai

To be a scientist you must be prepared to do experiments, and you must be very patient to wait until you have the results of the experiments. Here is a difficult experiment which even young children can persuade their parents to let them do.
Take a piece of chocolate and put it in your mouth.  Now the difficult part of the experiment: {don't bite it!} Be patient, keep the chocolate there and wait.
Here is what the results of the experiment should be.  The piece of chocolate becomes limp, then liquid, and its sweetness fills your mouth.
What did you learn from your experiment? Your body has a temperature of 37 degrees Celsius, so of course does your tongue. The heat from the tongue melts the chocolate. This works because chocolate melts at 34 degrees Celsius. This article is to tell you that this is not chance, but engineering. Chocolate is designed to melt in your mouth, that is one of the reasons eating it feels delicious.
Cocoa trees are native to Mexico and central America.  Their fruit looks like something between an orange and a melon and is purple in colour. Inside each fruit there are 30 to 40 white seeds, which are the size of plums. If you try to eat them they are really bitter.  Cocoa farmers harvest heaps of these beans and leave them to {rot}. This is the first step to making chocolate.
After fermentation (rotting) for about two weeks, the beans are dried and roasted. The carbohydrates (sugars and starches), long molecules inside these beans, are {caramelized}, broken up into smaller units and they turn brown. If you roast them too much you will only get black charcoal, which is all carbon.  Also the carbohydrates react with the proteins inside the beans, this is called a {Maillard reaction} and it makes a huge variety of flavourful molecules.
The Mayans of central America would grind the fermented and roasted beans and add hot water to make a thick drink they called {chocolatl}, which means "bitter water" in their language. When the Europeans conquered America, they exported the drink to the rest of the world. As you may have expected it was not a success.
In 1828 a Dutch company called van Houten came up with the industrial process of pressing these beans so that the "butter" (fat) of the cocoa flowed out.  The remaining powder was dark, smooth and sleek.  This pulverized powder, mixed with sugar and milk, was sold under the name "drinking chocolate".  This was a more successful product.
In 1847, an English company called Fry and Sons came up with a new idea.  They mixed the powder and clarified cocoa butter with some sugar back into a solid which they called "eating chocolate". Any one eating this could perform the experiment we saw earlier.  The butter melted releasing the powder and drinking chocolate was produced in your mouth.  This unique sensation led to a boom in the industry.
Then in 1875 a Swiss dairying company called Nestle decided they wanted to make it even less bitter, and they added their milk powder to the product.  Again this was a big hit with the market. 
After that different companies have kept on developing techniques to give you newer and newer flavours. Where the cocoa is grown, the weather there, how long the fermentation is done, how diseases of the cocoa bean are avoided, these are big secrets because thousands of crores of rupees are involved in the chocolate trade today.  Today almost half of the world's cocoa production is from the small African country of Ivory Coast.
Why does almost every one like chocolate?  It has some addictive ingredients but in very small quantities: caffeine, theobromine, cannabinoids.  Theobromine is even a poison for dogs and cats (so do not give chocolate to pets).  But even if you eat several bars of chocolate in a day it is only equivalent to one or two cups of strong coffee. 
Our bodies convert the cocoa butter into unsaturated fat, but unlike other such fats such as {ghee} ({nei}) cocoa butter does not seem to have any unhealthy effects.  Of course if you eat a lot of chocolates your body puts on weight. 
We have a long history of processing food in order to make it tasty. Amazingly, unlike many other products, chocolate seems to be deliciously engineered without dangerous side-effects.

Adapted from
{Stuff Matters}
by
{Mark Miodownik}