Learn about the chemistry of green coffee
Whenever we can, we remind consumers that the green coffee, It is nothing more than the seed that is inside the fruits that we get from the coffee plant. And once we open its fruit, we can see that there are two grains inside each cherry, looking at each other. We explain this valuable information from scratch the process that we know as grain to cup. Where the coffee is subjected to several stages that range from selection, roasting until finally reaching the palate.
The coffee world is full of surprises and includes chemistry in almost everything. Well, if you try to prepare a coffee by grinding these types of seeds, you will notice that this will be the complete opposite of what you imagine as a conventional cup. That's when a big question arises: What is it composed of?
In this article we will talk about each of the chemical compounds, which by nature are part of this small seed before undergoing the roasting process. So we invite you to continue reading and discover more about this.
What is green coffee?
It is that seed that is inside the coffee cherry, without having been roasted and the same one that has gained popularity in recent years. Depending on their origin, conservation and year of harvest, the colors of these beans will range from green, blue and brownish.
A notable characteristic is that the green coffee infusion is known for its intense aroma and being bitterer than a traditional espresso. Qualities that are due to its chemical compounds and that continue to captivate many consumers around the world.
When we prepare a cup of unroasted green beans, we can enjoy 100% of their properties. Experts in the field consider that green coffee is much healthier, while its consumption remains the same as that of a dark, roasted coffee.
Learn about the chemistry of green coffee
Before getting into the subject, it is necessary to point out that you have to know that there are countless studies on coffee. With the passage of time they have evolved and discovered new things. Some add to what is already known and others sometimes dismantle everything you thought you knew about coffee.
On this occasion, we have decided to base ourselves on the book The coffee roasters Companion of Scott Rao, one of the world's roasting gurus. Here we can find content related to the chemistry of green coffee. Like the physical and chemical changes that beans can undergo when they are roasted, roasting machines. Basic and necessary concepts of how we can plan the roasting, variables and analyze the final result. As you will see, it is quite complete and works wonderfully for those who are taking their first steps in the coffee industry.
On this occasion, we focus especially on the chemical compounds of a green coffee bean of the variety Arabic, because it is one of the most sought after by specialty consumers in the world.
Now, as we indicated at the beginning, normally in the center of a coffee cherry there are two beans together. However, there is a type of grain called snail which is considered a malformation of the seed. The reason is that, in your case, it has not been separated into two and that is why there is only one kernel inside the cherry. But this does not mean that it is bad, since the main problem is that it is a grain of a different density and size than the rest and when roasted it behaves differently.
Let's take an example, imagine that you are cooking and you put very thick pieces of potatoes and other thin ones. Surely one will be raw and the other will burn. Well, the same thing happens with snail grains. But if they are selected and only one batch is separated, it can even have a more intense flavor because all the chemical compounds are concentrated in a single grain.
While a generic raw coffee bean, specifically an Arabica variety bean, we will notice that They are dense seeds, and are composed of half carbohydrates of different types and the other half is a mixture of water, proteins, lipids, acids and alkaloids.
What are the main components of grain?
If you are new to the coffee world or are simply a very curious consumer, and would like to learn more about beans, then you have come to the right place. Below, we will explain each of them and you will be able to identify them like an expert.
Structure of green coffee
Green coffee is a polysaccharide, that is, a matrix that contains approximately a million cells. Within this matrix, cellulose is covered by hundreds of chemical substances that the roasting process will transform into oils and soluble materials which will determine the flavor of the coffee.
Once the grain is roasted, the cellulose is, in part, responsible for the aroma and providing viscosity to the drink. In short, it increases the perception of the body in the mouth. This factor is very important, because depending on the degree of roasting, the body will increase. But if the degree of roasting is too high and the cellulose is burned, the body's perception will plummet. In fact, part of that cellulose can also be burned when preparing coffee if the temperature of the water we use is very high.
In summary, the structure of cellulose green coffee represents half the weight of the grain.
Sugar in coffee beans
In case you didn't know, the coffee beans contain sugar. To be exact, between 6 and 9% of its weight. Don't forget that we always talk about the Arabica species. What is known as the sucrose of the bean is what is responsible for contributing to the development of the famous acidity of coffee. Because, during the caramelization process that coffee undergoes during roasting, sucrose produces acetic acid.
Lipids
It is also known as the fat levels of coffee, which are mainly triglycerides. This represents around 16% of the weight of green coffee. Although they are insoluble in water, depending on how you prepare the coffee, it could contain more or less lipids. For example, to prepare an espresso we use metal filters since the holes are thicker than in paper filters.
The lipids in the drink help retain the aroma and contribute to a greater coffee sensation in the mouth. A high lipid content is related to the quality of green coffee. However, it can also be a problem because they are beans that are more vulnerable to oxidation or becoming rancid after roasting and packaging.
Green coffee proteins
These represent between the 10 and 13% of the weight of green coffee. They react with other components during roasting and produce glycosylamines and melanoids which contribute to the bitter taste of coffee. As well as that brown tone and the aromas of toasting.
Caffeine and trigonelline
They are what are called alkaloids, and they represent 1% of the weight of green coffee and both are responsible for the bitterness and stimulating properties. On other occasions we have explained that the coffee plant, to protect itself from insects, produces caffeine, which is an incredible insecticide.
As you already know, Arabica coffee grown at higher altitudes usually has lower caffeine percentages than those grown at lower altitudes. Because the risk of being attacked by insects is lower. It should be noted that climate change is another factor that is affecting coffee crops, and that the presence of insects or pests at higher altitudes is also changing.
Regarding trigonelline, it is characterized by being the alkaloid that contributes the most to bitterness, and is also responsible for producing many aromatic compounds. Throughout the roasting process, it degrades and converted into niacin which belongs to the vitamin B group.
Humidity
Green coffee ideally has to have between 10% and 12% humidity. If it is lower, the color of the green coffee will be paler and it may be old or poorly stored. But if the humidity percentage is greater than 12%, there is a possibility that mold will form on the grains.
This is a very important fact when roasting coffee, because depending on the percentage of humidity we will have to apply more or less heat during the process.
organic acids
This group is made up of citric, quinic, caffeic, malic, acetic, formic and chlorogenic acids. The sum of all represents between 7 and 10% of the weight of green coffee. Although chlorogenic is the one with the greatest presence, with 6 and 8% of the weight. This organic acid influences the acidity, astringency and bitterness of coffee.
Gases and aromatic compounds
As you may already know, volatile aromatic components are responsible for the aroma. Green coffee contains more 200 aromatic compounds but they provide very little odor. Most aromatic compounds are created during roasting. Studies have even identified more than 800 in roasted coffee.
Learning everything about the chemical compounds in green coffee may be a bit complicated. But after having read this interesting article, it is now very likely that you have some more information and that which you will possibly put into practice if you dedicate yourself to the coffee world.
