Why does chocolate taste so good? A scientist unpacks the volatile chemistry

Whether it’s creamy milk chocolate truffles, baked in a devilishly dark chocolate cake, or even poured as hot cocoa, Americans, on average, consume nearly 20 pounds (9 kilograms) of chocolate in a year. Humans have enjoyed chocolate for at least 4,000 years, beginning with Mesoamericans who brewed a drink from the seeds of cacao trees. In the 16th and 17th centuries, both the trees and the drink spread around the world, and chocolate is now a trillion-dollar global industry.

As a food scientist, I’ve researched the volatile molecules that make chocolate taste so good. I also developed and taught a very popular college course on the science of chocolate. Here are the answers to six of the most common questions I hear about this unique and complex food.

6. How does chocolate get its taste?

Chocolate consumption has an ancient history rooted in indigenous tradition. In this image, an indigenous Amuzgo woman in Mexico uses her hands to roll raw cacao paste into balls, which are used to make hot chocolate.

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Chocolate starts out as a rather bland-tasting bean, packaged in a pod that grows on a cacao tree. In order to develop the characteristic taste of chocolate, two important steps are required: fermentation and roasting.

Immediately after harvesting, the beans are layered under leaves and fermented for several days. Bacteria produce the chemicals, called precursors, needed for the next step: roasting.

The flavor you know as chocolate comes from roasting through what chemists call the Maillard reaction. It requires two types of chemicals – sugar and protein – both of which are present in fermented cocoa beans. Roasting brings them together under high heat, causing the sugar and protein to react and create that wonderful flavor.

Roasting is something of an art form. Different temperatures and times produce different flavors. If you sample a few candy bars on the market, you’ll quickly discover that some companies roast at a much higher temperature than others. Lower temperatures maximize the floral and fruity notes, while higher temperatures produce more caramel and coffee notes. Which is better is really a matter of personal preference.

Interestingly, the Maillard reaction also produces the taste of freshly baked bread, roasted meat, and coffee. The similarity between chocolate and coffee might seem pretty obvious, but bread and meat? The reason these foods all smell so different is that the aroma chemicals formed depend on the exact types of sugars and proteins. Bread and chocolate contain different types. Even if you roast them the exact same way, you won’t get the same flavor. This peculiarity is one of the reasons why it is so difficult to make a good artificial chocolate taste.

5. How long can chocolate be stored?

Chocolate has different shelf lives, depending on whether it is milk or dark chocolate and how it is stored.

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As soon as the beans are roasted, this wonderful aroma is created. The longer you wait to eat, the more volatile compounds responsible for the odor will evaporate, leaving you with less flavor. In general, you have about a year to eat milk chocolate and two years for dark chocolate. It’s not a good idea to keep it in the fridge as it will absorb moisture and odors from the other things inside, but you can keep it tightly closed in the freezer.

4. What is different about hot chocolate?

To make powdered hot chocolate, the beans are soaked in alkali before roasting to raise their pH. Raising the pH to a more basic level will help the cocoa powder become more water soluble. But if the beans have a higher pH during roasting, the Maillard reaction changes, resulting in different flavors.

The taste of hot chocolate is described by experts as a smooth and mellow flavor with earthy, woody notes, while the regular chocolate flavor is pungent, with an almost lemony finish.

3. What defines the texture of a candy bar?

Historically, chocolate was consumed as a drink because the ground beans are very gritty — a far cry from the smooth, creamy texture people can create today.

After removing the shells and grinding the beans, modern chocolate makers add additional cocoa butter. Cocoa butter is the fat found in cocoa beans. But the beans don’t naturally contain enough fat to create a smooth texture, so chocolate makers add extra fat.

Next, the cocoa beans and cocoa butter undergo a process called conching. When the process was first invented, it took a team of horses a week to go in circles and pull a large grindstone to pulverize the particles small enough. Today, machines can do this grinding and blending in about eight hours. This process creates a smooth texture and also drives away some unwanted odors.

2. Why is chocolate so difficult to cook?

The “blossom” seen here – the white spots on the chocolate – can be caused by incorrect tempering of the chocolate during preparation.

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The chocolate you buy from a store has been tempered. Tempering involves heating the chocolate to just the right temperature during production before cooling it down to a solid. This step is necessary because of the fat.

The fat in cocoa butter can naturally exist in six different crystalline forms when it is solid. Five of these are unstable and want to transform into the most stable, sixth form. Unfortunately, this sixth form looks white, has a gritty texture, and is commonly referred to as a “bloom.” If you see a candy bar with white spots on it, it has bloomed, meaning the fat has rearranged into that sixth crystal form. It’s still edible, but doesn’t taste as good.

You can’t prevent blooming, but you can slow it down by heating and cooling the chocolate through a series of temperature cycles. This process causes all fat to crystallize into the second most stable form. It takes a long time for this form to transform into the white, gritty sixth form.

Melting chocolate at home breaks the temper. The day after you make your confection, the chocolate usually blooms with an unsightly gray or white finish.

1. Is chocolate an antidepressant?

The short answer is, sorry, no. Eating chocolate might make you feel happier, but that’s because it tastes so good, not because it chemically changes your brain.

This article was originally published on The conversation by Sheryl Barringer at Ohio State University. Read the original article here.

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