The two perquisites are a timer and a set of digital scales.
Making better coffee is all about eliminating variables, and one way to do that is to use the same amount of coffee per unit of water each time you brew. Using a digital scale to measure this takes just a second and allows you to better compare how much coffee and water is used each time.
Ideally, a ratio of 1:16 (that’s one-part coffee to 16 parts water, or about 9g of coffee to 150mL of water) makes a fairly strong cup of coffee. That said, some people go as high as 1:14 or as low as 1:30. It’s up to you to decide what tastes best, which is much easier to do (and replicate) once you remove all the guesswork.
Grind your coffee immediately before brewing for maximum flavour. Coffee begins to lose its flavour within 15 minutes of being ground, so grind just before you brew.
Unless you want to invest in a quality automatic burr grinder, a manual hand mill is the most affordable way to achieve a nice, consistent grind, though they do require a small amount of manual labour.
Blade grinders also work, but will produce inconsistent particle size, which can lead to over-extraction.
The next thing to consider is grind size. This will be dictated by your choice of brewing device, the coffee beans themselves, and your personal tastes.
Some general rules are: the finer the grind size, the more extraction will take place due to the greater surface area. (And, in a pour over, the longer it may take for water to filter through.) The coarser the grind, the less extraction there will be. Under extraction leads to sour tastes, while over extraction will create more of a bitter flavour profile. If your coffee is too sour, grind finer. Too bitter, on the other hand, means you need to grind coarser
Most automatic coffee makers miss out on a crucial step. However, when using a manual pour over you can pre-infuse or “bloom” the coffee. This is achieved by pouring hot water over the grounds to help release any remaining carbon dioxide gas left over from the roasting process. Skipping this step will allow the carbon dioxide to repel water during part of the brewing process, effectively making the brew weaker.
The water temperature you brew your coffee with will affect how your coffee tastes. The recommended range is 90–96°C/195–205°F. However, the exact temperature you use should depend on the coffee you’re using and your own personal preferences.
Basically, the hotter the temperature, the greater the degree of extraction. If your coffee is tasting too sour, use hotter water; too bitter, use cooler water.
No matter what your brew method is, it’s important to make sure that you’re recording how long you’re brewing for as it can have a significant impact on flavour. Luckily, most people have a timer on their phone nowadays.
Once you’ve started recording the time, you can also adjust it if you want to amend your final cup profile. With filter, pour more of the water early on for a fruitier, more acidic cup of coffee. For greater body, on the other hand, keep pouring for longer. And with immersion methods, such as the AeroPress, Clever, or French press, simply change how long the grounds are left in the water.