When it comes to brewing coffee, whether you are using an electric kettle, stovetop kettle, microwave oven, or even a cauldron over an open flame, the only thing you need to concern yourself with for perfect flavor extraction is getting the water to the optimal temperature.
Obviously, if you are using a vacuum siphon, moka pot or an auto-drip maker to make your coffee, then you don’t need to worry about a separate step to boil your water. Furthermore, if you have a professional machine for making espresso, all you need to do is program the temperature for the boiler. However, if you are dealing with an AeroPress, French press, manual drip, or a plain old mug of water, you can choose the temperature you desire.
Consider this your official barista training, and here are the steps to making your water the perfect temperature:
For starters, you need cool water. Bottled or filtered water is wonderful, but if you must utilize unfiltered water from the tap (acceptable, but not recommended), be sure to allow it to run a bit before filling what you need. Distilled water should not be used. The fact that there aren’t any minerals in it will negatively affect the taste of your brewed coffee.
Heating the Water
Secondly, is the most important coffee rule of all. Do not use boiling water! You could heat water to a boil, and allow it to cool off, or just pull the kettle off before it begins to boil. The SCAA states that the ideal temperature range is around 200 degrees during the majority of the brewing cycle (90 percent or more). If water is not hot enough, the coffee will lack flavor and taste under-extracted. If water is too hot, your coffee will taste extremely bitter.
Testing the Water
There are a few ways to test the temperature of your water. You could use a stem thermometer for testing, or, if you have a stovetop kettle; just watch it and pull it before it reaches a boil. Electric kettles are even easier, as it will boil and then stop on its own. You can then just allow it to cool a few minutes. Once you use a metal thermometer to know when to turn off your whistling kettle or gauge how long your boiled water needs to cool, you shouldn’t need it again unless you choose to brew your coffee at a different temperature.
Using a thermometer for calibration is important for testing your machine. If you don’t, you won’t have an answer as to why your coffee has the flavor that it does. With some trial and error, you will be able to find the results that work for you. Once you taste your “correctly” brewed coffee, you can tweak the temperature for your liking. If you like a tasteless, flat coffee, then by all means brew at 150 degrees; no one will come arrest you.
Barista courses can be very helpful in learning everything you need to know about proper water temperature and how to brew great coffee, but let’s start with a few basic suggestions.
Heat some additional water, and use a little to preheat your mug while you wait for the coffee to brew. Bear in mind that some water is going to evaporate during heating, so filling a kettle won’t yield a “full” kettle. It’s always better to overfill a bit and end up with too much rather than too little.
Make sure to pour out any leftover water in your kettle. Not doing so will allow stale water to coat the kettle with harmful mineral deposits, and it’s not like you are going to reuse the water anyway.