Why Are Coffee Beans Roasted? Fact Not Fiction

Did you know that coffee beans are not beans? They are seeds that are green in their raw state, and they change from green to different brown shades and even black when roasted. The color of coffee “beans” depends on its roast level.

Roasting coffee beans brings out the flavor and aroma inside the green beans and makes them ready for brewing. Unfortunately, green coffee beans have none of the roasted bean’s characteristics – they are spongy and soft and have a grassy smell, and you can’t brew it in that state.

Chemical changes occur when beans are roasted to very high temperatures. When they reach their desired state, they are cooled immediately to discontinue the process.

When you roast beans, they weigh less because the moisture has evaporated, and they smell as coffee should.

We will explore more of what happens when coffee beans are roasted and their roasting levels to appreciate the process better.

What Happens When Coffee Beans Are Roasted?

Raw, green coffee beans experience physical changes during the roasting process. The heat transforms the compact, dense beans from a green seed to a flavorful and aromatic bean. Let’s look at the changes that occur due to the roasting process:


Prior to roasting, coffee bans are blue-green and change to brown due to the development of melanoidins. When amino acids and sugars combine under heat, polymers begin to form; these are melanoidins.

A papery outer layer, called chaff or silverskin, will also come off during the roasting process. Roasters often use the level of color to judge profile and quality.

Dried green, process beans contain about 10 to 12 % of water, while roasting reduces this to about 12%. Additional water forms by the chemical reaction but is vaporized when roasted – changing the coffee structurally.

Moisture And Mass

Roasting reduces the overall mass of the beans due to the moisture loss and transformation of dry material into gases.

Generally, beans lose 12 to 20% of their total weight. Roasters monitor percent weight loss to determine which batched require more attention in quality assurance.


Coffee beans have solid cell walls with external rings to increase their strength and stiffness. However, the roasting process increases the temperature and transforms water into gas creating high-pressure levels inside the bean.

This pressure changes the anatomy of the cell walls from stiff to rubbery. This is due to the presence of polysaccharides.

The internal body pushes out towards the cells, resulting in a gassy void in the middle. The beans expand in volume as their mass declines.

This gas build-up is carbon dioxide that will emit after roasting. Roasting makes the beans more soluble due to the porosity increase. This is essential for making them into a delicious cup of java.


Coffee beans contain oils or lipids that come to the surface of the beans as the high internal pressure causes compounds to move from the bean’s center.

The oils help to contain volatile compounds inside the cell. These chemicals contain a high vapor pressure at room temperature and are essential for creating coffee’s aroma and flavor. Without the oils, these compounds would disperse.

The longer they roast, the more intense the physical transformation. Roasting decreases the density continuously. More gases develop as time moves on. In dark roasts, you will see oil move to the bean’s surface.

These changes explain why dark roasted coffee tastes different from a lighter roasted one. Significant chemical changes also impact the profile.

What Is The Difference Between Roasted And Raw Coffee Beans?

Surprisingly, there is a growing interest and demand for unroasted coffee beans. Raw coffee beans contain some health benefits which we will examine:

Raw Coffee Beans Are lower In Caffeine.

Raw coffee beans come directly from the Arabica plant and are left in their natural state before being packaged then sent to consumers.

These coffee beans are ideal for individuals looking to reduce their caffeine intake. A cup of roasted coffee contains around 100mg of Caffeine, a cup of unroasted coffee only has approximately 20 mg of Caffeine. So you won’t lose any sleep with this beverage.

They Are Full Of Antioxidants

The essential ingredient in green coffee beans is chlorogenic acid. This powerful antioxidant helps regulate the body’s lipid and glucose content, offering it various health benefits.

It helps to guard cells against free radical damage and reduces your body’s overall oxidative stress levels.

Free radical damage can make you feel fatigued, it weakens your immune system, and increases your risk of inflammation. The high antioxidant levels in chlorogenic acid in raw coffee beans keep those issues at bay.

Raw Coffee Beans Support Weight Management

A recent stud revealed that volunteers who tried green coffee for weight loss had a 16% decrease in body fat and a reduction of 10.5% in body weight.

This is primarily due to the chlorogenic acid properties, which boost energy levels and helps to burn fat stores in the body. It can also lower your metabolism and reduce cravings.

It can even slow down the process of sugar absorption in your bloodstream, keeping your insulin levels consistent.

It Can Improve Mood And Focus

The lowered caffeine levels in green coffee beans can boost your cognitive performance and enhance your mood. This is because caffeine and chlorogenic acid block the adenosine neurotransmitter in the brain.

This is a central nervous system depressant. It increases your energy and dopamine levels.

The surge of dopamine helps to prevent stress and depression, working to increase your motivation levels.

It Helps To Lower Blood Sugar Levels

Green coffee beans help maintain your blood sugar levels and blood pressure within a healthy range due to the chlorogenic acid.

Chlorogenic acid is packed with hypoglycemic properties that interacts with your body’s lipid metabolism, thus lowering your cholesterol levels.

Since green coffee keeps inflammation at bay, you are unlikely to crave sugary foods as much -this keeps your glucose levels low. This is essential for maintaining a healthy blood sugar level.

Green coffee beans can lower your risk of developing type 2 diabetes. This is because chlorogenic acid reverses the build-up of fat from years of poor nutrition, affecting the genes responsible for adipogenesis.

Green Coffee Beans Flavor

Green coffee beans are a big hit with the medical community due to their numerous health benefits. However, don’t expect green coffee to taste like coffee.

Many people describe the taste as grassy and acidic – something they would prefer not to drink. If you drink green tea, you may handle the taste of green coffee.

How Do Coffee Beans Get Roasted?

Coffee starts as a small red fruit picked and processed to remove the skin, pulp, and inner skin parchment. When the process is finished, the inner seed, which is green, is dried.

We know that roasting forces moisture out of the bean, making it dry and expand in volume. Some of the natural sugars convert to CO2 gas, and others caramelize into flavors that give the coffee its distinct taste.

There are ten stages of roasting coffee. It’s up to the roaster to decide which is the preferred stage:

1. GREEN. The coffee beans keep their natural green essence despite temperature increases.

2. YELLOW. Gradually the color turns yellowish, and the beans release a gassy odor.

3. STEAM. The water inside the bean evaporates and releases steam.

4. FIRST CRACK. ( Cinnamon Roast). The sugars inside the beans begin caramelizing, and you can hear a cracking sound.

5. CITY ROAST. After the first crack, the beans reach a minimum roast level that is acceptable to most coffee lovers for grinding and brewing.

6. CITY PLUS ROAST. As the beans caramelize more and the beans migrate, the beans swell in size. This roasting level is popular.

7. FULL CITY ROAST. This is an even darker roast whereby the beans nearly reach their second cracking.

8. SECOND CRACK (FULL CITY ROAST PLUS). The beans go through a more violent cracking, and the roast releases more intense layers to the flavor.

9. DARK ROAST (FRENCH ROAST). The sugars burn as much as possible without ruining the flavor, and the smoke becomes pungent. The beans’ structure will break down, but it remains in the confines of good flavor.

10. BURN. The smell will go from pungent to rank, and the beans are burnt

Final Thoughts

Coffee beans are roasted to release flavors and aromas locked within the coffee beans. The roasting process is complex, and it transforms the beans from the inside out to produce toasty beans with a delicious aroma. Most of us look forward to that smell in the morning, and it is all due to roasting.

Many people are unaware that green coffee is a thing now with its numerous health benefits. It’s worth trying this coffee just for its medical properties, but don’t expect it to taste like your regular morning brew. The flavor can only be described as grassy and acidic.

Roasting is a method that deserves appreciation; it offers flavor and a rich aroma into our everyday life.

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