In total, coffee contains over 600 chemical compounds, with robusta exceeding 600, and ordinary arabica
boasting more than 900. High-quality specialty coffee can even contain over 1,000 different compounds! Each
variety and type of coffee has its own unique base and additional chemical makeup. This creates the distinctive
flavors, aromas, bean appearance, and how the drink is perceived. In this article, we’ll explore the main chemical
groups found in coffee (both arabica and robusta).
Alkaloids
These are nitrogen-, carbon-, and hydrogen-containing compounds with an alkaline nature (hence the name,
from “alkali”). They have a bitter taste, no smell, and often form crystalline salts when isolated from the plant.
The most famous alkaloid in coffee is caffeine — the very reason most of us drink coffee. Alkaloids are biologically
active and influence how our bodies react to food and drink.
Other well-known alkaloids include morphine, strychnine, nicotine, serotonin, dopamine, and atropine.
Coffee also contains trigonelline, another bitter alkaloid that breaks down during roasting and strongly contributes
to coffee’s aroma..
Anhydrides
These are oxides that form salts derived from organic acids. In food and beverages, they act as oxidizing
agents and preservatives.
Aromatic Compounds
These are responsible for the aroma profile of the drink. Roasting changes these compounds, meaning the
roast level directly influences the final taste and smell of the coffee.
Acetoin
A fermentation byproduct with a creamy, buttery, and caramel-like smell. It is used as a food flavoring and
is also found in beer, wine, and candy.
Proteins
Proteins are the building blocks of the human body, made from 20 types of amino acids. They are essential
for energy production and bodily function. Think of meat — a prime example of protein-rich food.
Ketones
These are fat metabolism byproducts and serve as low-energy fuel alternatives for cells, as opposed to high-energy sugars (carbohydrates).
Acids
There are over 100 types of acids found in coffee. The most notable include chlorogenic acids, aliphatic
acids, quinic acid, and a range of amino acids, both simple and complex.
Lipids
In simple terms — fats. In coffee, these are presented as visible or hidden oils. Arabica contains around 5
times more oils than robusta, contributing to its richer and more complex aroma, especially in specialty coffee.
Melanoidins
These are roasting byproducts that contribute to the roasted flavor and color (from light tan to deep black).
They form via the Maillard Reaction, a chemical process that occurs during roasting.
Minerals
These include simple chemical elements found in either pure form or as compounds: iron, calcium,
magnesium, selenium, zinc, etc.
Polysaccharides
These are carbohydrates that include glucose and serve as pure energy sources. They give coffee its subtle
sweetness — and can contribute to weight gain if you skip the gym.
Organosulfur Compounds
Highly aromatic substances, sometimes components of amino acids. If unbalanced, they can cause off-
putting smells like garlic or mold..
Alcohols
Volatile compounds that enhance floral and fruity aromas. Their concentration increases during fermentation
and decreases during roasting — meaning lightly roasted coffee contains the most. As their levels drop, chocolate
and nutty notes become more dominant.
Triglycerides
A form of fatty acids, both saturated and unsaturated. Though not abundant in coffee, they are commonly
found in red meat, rich cheeses, and sweets, including baked goods.
Phenols
Acidic, aromatic compounds that act as flavor enhancers, preservatives, and colorants. Their content
increases during the Maillard Reaction during roasting.
Esters
Food-grade emulsifiers and flavorings, esters are derivatives of fatty acids and form during the thermal
processing of coffee as fats break down. Outside food, they are used in plasticizers and solvents in various
industries.
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