After procuring quality coffee, there is a bit of work involved in getting a great cup time and time again. There are a few variables at play that can make your life either easier or harder, and until maybe five or six years ago, there was a huge swath of the coffee industry that insisted coffee drinkers followed their explicit steps and used their exact equipment or else they aren’t truly experiencing coffee. This mindset is still prevalent, but it’s something that the coffee industry at large is trying to shake because there is no true, singular way to make or enjoy coffee.
Coffee is a solution—the roasted coffee is the solute and hot water is the solvent. In the industry, we call this extraction. It’s really common for too much coffee to be extracted (overextraction) and the resulting brew will taste bitter and burnt, and this is because the hot water starts to extract flavor from the charred plant-like structure of the coffee beans after it has dissolved all of the tasty goodness. However, if there is too little coffee dissolved (underextraction), then a cup of coffee will taste sour and grassy.
When brewing coffee at home, finding the Goldilocks zone can be difficult if you don’t know where to begin. However, understanding the five factors that all work together to brew coffee will help demystify the once-esoteric art of brewing great coffee. They are:
- Water temperature
- Contact time
- Grind size
- Agitation
- Ratio
Water Temperature
Many solutes—like sugar or salt—dissolve much quicker and easier in warmer water. Coffee is very similar—the hotter the water is when it comes into contact with the ground coffee beans, the more the water will extract.
Grind Size
The coarser coffee is ground, the larger the individual grounds are, and the more difficult it is for water to extract flavor from them. For finely ground coffee, the small size of the grounds greatly increases the surface area and increases extraction.
Contact Time
The more time water spends in contact with ground coffee beans, the more it will extract. Inversely, the less time, the less the water will extract.
Agitation
Water will begin extracting coffee the minute they come into contact with each other, but moving or stirring the slurry of soaked coffee can speed along the process.
Ratio
Water can only hold so much material. Most water already contains some sort of mineral content, and, like a sponge, each droplet has a limit to how much it can absorb. The more water that comes into contact with coffee, the more dissolved content it can hold, and the more it will extract from the ground coffee.
Each factor tugs and pulls at one another to produce the final product—a cup of coffee. Every brew anyone has ever tasted—the worst, the best, and everything in between—is a result of these five items interplaying. In the next chapter, I’ll discuss how to harness these elements to make consistently delicious coffee time and again.