It is officially time for coffee school today, so we’re taking you back to the classroom, where we will teach you how to read a coffee chemical formula.
Why learn about the chemical composition of coffee, you ask? Well, some say that making a great cup of coffee is an art form. We say, “true”, but it’s also good science.
For instance, have you noticed that the coffee you make at home tastes different from the coffee you drink at a coffee shop? Why do you head to the coffee shop and still get excited about your cup even though you know how to brew one at home? It’s Coffee Chemistry!
It is the Barista’s training and their abilities to leverage physics and chemistry. It is an added feather to your hat when you understand these chemical formulas that impact the taste and quality of your coffee.
A delicious cup of coffee results from a combination of factors, including temperature, water chemistry, particle size distribution, water-to-coffee ratio, time, and, perhaps the quality of the green coffee.
What Is A Chemical Formula?
You don’t have to be a chemistry genius to understand chemical compounds and formulas. We’re here to simplify the process and enhance your understanding of the coffee-making process.
Let’s understand the physical nature of coffee when you use it. For instance, do you notice coffee sticking to your tools? How finely ground is it? Does it dissolve quickly?
Once you’ve noticed those aspects of your coffee, it’s time to understand its chemical makeup.
The element symbol is followed by a subscript, which denotes the number of atoms. We’re going to be focusing on understanding this coffee chemical formula for our study.
Simple Chemical Formulas
Water is made up of two hydrogen atoms and one oxygen atom in each molecule–H2O.
Sodium Chloride is made up of one sodium atom and one chlorine atom in each molecule —NaCl (Haskins).
H2O
Several atoms of one element are present in the molecules of many different substances. The number that follows an element’s chemical symbol indicates how many atoms it contains.
Water is made up of two elements: hydrogen and oxygen, respectively. You can identify that a water molecule contains two hydrogen atoms by looking for the number “2” following the symbol for hydrogen. Since there is only one oxygen atom per water molecule, no number follows the oxygen symbol.
NaCl
The number of capital letters in the chemical formula is the best indicator of how many elements are contained in a single molecule of table salt. The molecule has two components since there are two capital letters in this instance: the “N” in Na and the “C” in Cl.
What Is The Chemical Composition of Coffee?
Chinese material medicine describes coffee as being flat, astringent, and mildly bitter. It has the effect of making the drinker awake, and it has the potential to cause diuresis and stomach strengthening. It is employed for waking, diuresis, and stomach support.
What Are The Compounds Found In Caffeine’s Chemical Formula?
According to research reports, alkaloids, phenolic acids, flavonoids, terpenoids, sterols, and volatile components are the main components found in the chemical formula. These compounds have a variety of pharmacological effects, including insulin sensitization, improved sugar metabolism, anti-diabetes, and liver protection effects.
The official chemical makeup of coffee is 2-3% Caffeine, 13% Protein, 3-5% tannin and 10-15% fixed fat.
Caffeine is a trimethylxanthine and a purine alkaloid that stimulates the central nervous system (CNS). The chemical formula for caffeine is C8H10N4O2. It appears as a tasteless, white, crystalline purine with no odour. It is a naturally occurring methylxanthine alkaloid found in the seeds, leaves, and fruits of various trees and plants indigenous to South America, East Asia, and Africa.
How Does Caffeine Stimulate The Central Nervous System?
Coffee, tea, cola/soft drinks, energy drinks, chocolate, and cocoa are the most popular foods and drinks containing caffeine. The central nervous system is stimulated by dietary caffeine intake (2–3 cups of brewed coffee/3.3 mg/kg), which also boosts cardiac output in women, increases vascular resistance in males, and raises blood pressure in both sexes (Saud and Salamatullah).
How The Chemicals In Caffeine Impact Us
Coffee’s somewhat bitter flavour is due to its chemical formula, which contains 10% caffeine and roughly 6% chlorogenic acid. The amount of caffeine in beans decreases during roasting. The beverage and pharmaceutical industries both utilize artificial caffeine and caffeine that have been decaffeinated.
Synthetic caffeine made from uric acid and formamide is produced by methylating xanthine. Caffeine is a CNS (Central Nervous System) stimulant frequently mixed with another medication and used in analgesic formulations. The chemical formula in caffeine consumption entails how each molecule interacts with the other variables (Latosińska and Latosińska).
What Does Roasting Coffee Look Like Chemically?
Amino acids and sugars interact when coffee beans are heated in the roaster, starting a series of chemical processes that give the beverage its aroma, flavour, and colour.
What Is A Maillard Reaction?
The Maillard Reaction, as it is known, occurs in practically all cooking. The polysaccharides, or sugars, make up most of the coffee bean, although they also contain proteins, lipids, and minerals.
The coffee embryo must receive nutrition from the seed to germinate one day. The components of the roasting process include these sugars, proteins, lipids, and minerals.
A few dozen molecules in the coffee bean are transformed into hundreds or perhaps thousands of aromatic compounds that give coffee its distinct flavours through the Maillard Reaction.
These substances include the organic acids that give coffee its brightness, such as malic, acetic, and citric acids, to name a few. Coffees can have a variety of flavours, including sweet, earthy, caramel, and butterscotch, thanks to other chemicals such as aldehydes, furans, and pyrazines (Wang and Lim).
How Strecker Degradation Affects Roasting
Although Strecker Degradation is a less well-known response in coffee roasting, it significantly affects the finished product. The actual reaction is transforming an amino acid into an aldehyde, ammonia, and CO2 when an oxidizing agent is present (Teranishi et al.).
How Pyrolysis Affects Coffee
Pyrolysis is the term used to describe the high-temperature, chemically inert decomposition of materials. The most notable pyrolytic change during coffee roasting is sugar caramelization. However, pyrolysis can also happen when roasting past the first crack and into the second crack. This pyrolysis causes the coffee to become darker in colour, have larger levels of melanoidin, and have a “roast” or, in more severe situations, “charred” flavour.
The Process of Oxidation
The act of oxygen removing electrons from another molecule is known as oxidation. Due to their uneven distribution of electrons, these molecules become unstable and start interacting with nearby molecules. These unstable substances, known as free radicals, are the main culprits behind browning, aging, rusting, and, in the case of coffee, staling.
How Oxidation Impacts Coffee Grinding
Once your coffee is roasted, you start to race against oxygen and time, especially because the next step, grinding, increases the effects of oxidation.
After roasting, carbon dioxide produced during the roasting process and stored inside the bean progressively releases from the bean, thereby impacting the chemical formula organically. This CO2 release slows the effects of oxidation. Within minutes of grinding, the CO2 will disappear.
The coffee bean itself safeguards the delicate flavour and fragrance ingredients. Some of these substances are contained inside proteins and carbohydrates and are only released when disturbed. Over many weeks, the coffee loses these aromatic components even as a whole bean due to evaporation and oxidation. Unfortunately, the most fragrant chemicals are also the most sensitive. Once crushed, these compounds start to oxidize at once (Clifford et al.).
How Temperature Affects Coffee
The temperature controls the oxidation and fragrance diffusion mechanisms that we discussed above. Molecules in the chemical formula move in response to temperature; the hotter the coffee bean becomes at any stage of its use, the faster it travels.
The likelihood that the scent will escape and oxygen may harm the bean increases as they move quickly. Theoretically, coffee could be kept fresh indefinitely if it cooled to zero.
How Chemicals Impact Coffee Aroma
Using a tool known as a gas chromatograph/mass spectrometer, we analyse the coffee scent’s chemical makeup to investigate the coffee aroma.
These are two connected devices; the first separates various molecules that make up the aroma, and the second can measure their mass, allowing us to identify the specific aroma compound we are looking at.
Based on such data, we can define freshness indices, which are ratios between various fragrance components. These metrics are very useful for determining how various factors affect the scent of coffee.
We can look at four quite diverse aroma compounds and observe how they change during coffee storage. In this way, coffee aroma science helps us to understand why coffee changes profile as it ages. These are the four aroma compounds:
- Methylpyrazine
- 2,3 butanedione
- Methanethiol
- Propanol
Enzymatic, dry distillation and sugar browning are the three basic categories into which the Specialty Coffee Association (SCA) divides coffee scents (Rowe et al.).
Enzymatic
Aromas produced as a by-product of enzyme reactions in coffee beans during growth and processing are called enzymatic aromas. These aromas are frequently described as fruity, floral, and herbal.
Sugar Browning
These aromas are usually what you smell in a coffee shop, making you want to order a mean cup of coffee. The nutty, chocolate-y, caramel-y aromas develop because of the Maillard reaction.
Dry Distillation
During the roasting process, scents from dry distillation and sugar browning appear. Burning plant fibres release dry distillation scents typically described as ‘carbon-y’, spicy, and resinous.
How Are The Gases Formed?
In the course of roasting, gases are created in the coffee beans. During roasting, extreme heat is applied to green coffee beans, which triggers chemical reactions that result in the breakdown of carbohydrates, and the darkening of the bean’s colour, creating water and carbon dioxide.
The sound of the beans splitting during roasting is a good sign that gas is being released. Gasses are produced throughout the roasting process, but frequently there isn’t enough time for them all to escape.
Unexpectedly, a significant portion of newly roasted coffee is gas. Approximately 1% of freshly roasted coffee, which eventually releases gas during storage, can be said to be gas. (complete degassing takes about 1-2 months for whole roasted beans).
Darker and faster roasts produce more gas and release it faster, while degassing can be marginally influenced by coffee origin, variety, and processing. The roast profile has the biggest impact on the amount and duration of degassing.
Coffee Degassing
The time when gas escapes from roasted coffee beans is known as coffee degassing. This procedure, which can take two to three weeks, begins right after the roasting phase. It’s not a good idea to brew coffee right away after it has been roasted because that is when most of the gases depart the bean.
Extraction occurs when hot water and coffee grinds come into contact, producing coffee flavour. Gas bubbles that keep the water and coffee from coming into contact result in weak flavour and poor coffee extraction.
How Long Does Coffee Take To Degas?
The ideal period for a coffee to degas varies depending on how it was roasted, cultivated, processed, and brewing method, though the range is often between 3 and 2 weeks. For instance, you can use beans as soon as a few days after roasting if you’re using an immersion or drip method to make coffee, such as a pour-over or French press. It is a result of longer coffee/water interaction time.
Conclusion
A great barista is aware of what goes into the chemical makeup of coffee to give it a distinct twist and to keep you coming back for more! Hopefully, we have helped simplify how coffee science works so that you get to experiment with different roasting, grinding and brewing techniques. Furthermore, now you know a bit more about how to store your coffee for the best results because you understand the impacts on flavour, due to the constant action of oxygen and carbon dioxide.
For an even more hands-on coffee education, get trained as a professional coffee maker at one of Australia’s Top Barista Training Schools.
References
- Rowe, David, et al. More Fizz for Your Buck: High-Impact Aroma Chemicals.
- Clifford, Michael N., et al. “Metabolism of Phenolics in Coffee and Plant-Based Foods by Canonical Pathways: An Assessment of the Role of Fatty Acid β-Oxidation to Generate Biologically-Active and -Inactive Intermediates.” Critical Reviews in Food Science and Nutrition, 13 Oct. 2022, pp. 1–58. Accessed 13 Apr. 2023.
- Haskins, Julia. “Sodium Chloride.” Healthline, Healthline Media, 15 Jan. 2013.
- Latosińska, Jolanta Natalia, and Magdalena Latosińska. The Question of Caffeine. Google Books, BoD – Books on Demand, 21 June 2017. Accessed 13 Apr. 2023.
- Rijo, Bruna, et al. “Catalyzed Pyrolysis of Coffee and Tea Wastes.” Energy. Accessed 16 Nov. 2021, vol. 235, Nov. 2021, p. 121252.
- Saud, Shah, and Ahmad Mohammad Salamatullah. “Relationship between the Chemical Composition and the Biological Functions of Coffee.” Molecules, vol. 26, no. 24, 16 Dec. 2021, p. 7634.
- Teranishi, Roy, et al. Flavor Chemistry: Thirty Years of Progress. Google Books, Springer Science & Business Media, 6 Dec. 2012, Accessed 13 Apr. 2023.
- Wang, Xiuju, and Loong-Tak Lim. “Chapter 27 – Physicochemical Characteristics of Roasted Coffee.” ScienceDirect, Academic Press, 1 Jan. 2015, Accessed 13 Apr. 2023.
- Zumdahl, Steven S. “Water.” Encyclopædia Britannica, 4 Oct. 2018
