Dialling in my French Press Coffee
For the longest time, my one and only brewing option at home was a 3-cup French press. The press is affordable, the process is simple and you could quite easily get great coffee out of it.
I was not making great coffee though. My coffee was inconsistent, frequently bad and if I did make a good brew I had no idea how to replicate it.
I was doing the following things wrong:
Using the recipe of the bag.
Not measuring anything.
Not sticking to times.
Using random ground coffee with any grind size.
I had given no thought to the grind size, ratios, water temperature, how to keep the French Press coffee hot, the recipe and methods I was applying and many other important brewing requirements.
I put in some effort to fix this. I’m going to share what I researched, what I learnt and what I did to finally get to grips with French press brewing. What I found was that the key to improvement was understanding critical concepts, tracking and monitoring my brews while implementing a basic process that can be altered based on the resulting brew.
While I still have some major steps to take to really get the most out of it, I am on the path of consistency and better French press coffee.
Understanding brewing in a French press
Here are the common terms and concepts associated with the French press and what I understand now:
Immersion brewing: This is a brewing method where the coffee grounds are completely saturated in water for a period of time. With the French press the coffee grounds in the beaker/carafe are covered with water for 4 to 5 minutes, ensuring that all the grounds are “immersed” and the soluble coffee content is dissolved into the water, thereby brewing coffee.
Grind size: Coffee beans are ground into a range of sizes. The grind size is selected according to the brewing method but more importantly, it is related to the filter used in the brewing method being applied. The mesh filter found on a French press plunger is better suited to filtering out coarse grinds. Finer grinds will slip through the filter and into your cup.
Grind size consistency: Grinding is an imperfect process. Coffee beans are organic material varying in size, moisture content and other factors. The mechanical process of grinding them is not exact. In combination, you are likely to get a large volume of grounds at the size you want, but some of it will be larger and the rest of it will be finer than the target size. So, even with using a coarse grind setting, there are finer grinds in the batch, meaning you will still get some sediment at the bottom of your cup.
Filter effectiveness: The metal filter in the French press plunger may be somewhat less effective at keeping your cup sediment free. Paper filters used in other brewing methods are better at this. But in the French press, it does allow the oils to filter through, adding to the flavour and body of the coffee. Paper filters filter out these oils.
Brewing time: The dissolvable parts of the grounds need time, pressure, heat and agitation (in any combination) to dissolve. With the French press your main option to extract the coffee is time, but heat and agitation are also options.
Agitation: Agitation refers to stirring the coffee grounds while immersed in the water. A short agitation period (15 to 30 seconds) assists with ensuring that all the grounds are saturated. Longer agitation periods can promote extraction, increasing the strength of the brew and development of the taste.
Heat: Heat from the water accelerates extraction. Cold brewing takes a long time to fully extract the dissolvable coffee parts. Water heated to the correct temperature speeds up the extraction. Excessively hot water can contribute to over-extraction which is bad for flavours and tastes. The optimal heat is anywhere between 90 to 97 degrees Celsius (195 degrees Fahrenheit to 205 degrees Fahrenheit).
Heat dissipation: Most French press recipes advise a brew time of 4 minutes or more. In that time, the hot water poured into the French press beaker will cool down. It will cool down faster if the beaker is sucking heat away from it. And the brew will cool down further if mug sucks more heat away. And then, when you add cold milk to it, you are left with a luke-warm cup of coffee. The way to avoid this is to preheat the beaker, mug and if necessary the milk. And as an added benefit, preheating the beaker means that the heat from the brewing water is maintained for a long period, thereby assisting the extraction process.
Coffee dose: The coffee dose is the amount of coffee you add to the brew. It shares a critical relationship with the amount of water added. The ratio of coffee grounds to water is an indicator of the strength of the brewed coffee at the end of the correctly timed extraction.
Strength: Strength refers to the amount of coffee that was dissolved into the brewing water. More dissolved coffee means a stronger brew. Less dissolved coffee means weaker brew. This is different from flavour and taste, and the intensity that may accompany them. Strength can be affected by the coffee dose and by the coffee grind. Finer grinds can help more coffee dissolve, thereby increasing the strength.
Ratio: The ratio is determined by the amount of coffee added to a specific amount of water. Here’s the equation I use:
Water (in grams or volume) / Coffee grounds (in grams or volume) = coffee: water ratio
Here’s how it works:
If I brew with 300g of water and 20g of coffee then 300 divided by 20 = 15. The ratio of coffee to water is 1:15
If you want stronger coffee, lower the 15… e.g. 1:13
If you want weaker coffee, increase it… e.g. 1:17
But, if you want the same volume of brewed coffee at the end, adjust the coffee dose, not the water.
Weight versus Volume: The estimation errors caused by measuring coffee grounds by weight are well documented. You can get a rough measure, but it will never be exact, so the ratio you are working by will not be accurate. You will always have inconsistent strengths and extractions. Scales will improve consistency and repeatability of your brews. But if you don’t have one, don’t let that stop you from trying. Figure out a way to measure and stay consistent.
Measure the volume of your cup/mug: You need to know what you want to get out of the brew in order to correctly measure the water needed in the extraction process, and therefore to correctly calculate your extraction. Don’t forget to account for milk… it takes up space and can weaken the brew.
How to over-extract the brew: Over-extracted brews are bitter, heavy, dry, empty. The wrong, unpleasant extreme flavours and tastes are extracted. This is a symptom of the following things (individually or in combination):
1. Very hot water
2. Too much agitation
3. Too long brew times
These main causes may have greater effects if the grind size is too fine. Finer grinds release their flavours more easily than coarser grinds. It can also be exacerbated by dark and very dark roasts.
How to under-extract the brew: Under-extracted brews are sour but in an unpleasant, off-putting way. These brews are also thin, sometimes salty and just leave your palette quickly. This is a symptom of the following things:
1. Water that is too cold
2. Insufficient agitation
3. Too short brew times
The water just does not enough time or energy to extract the flavours. This could be worsened by using coarse grinds in combination with the above issues.
Correctly extracted brew: Along with getting your desired strength by adjusting the dose and grind size, you can also adjust the water temperature, agitation and brew time to get you to a brew that tastes complex, flavourful and pleasing with a good finish. You’ll know when you are close.
Tracking and tasting French press brews
The best baristas and brew masters will tell you to keep track of your brews, and that is where I started.
I wrote out a recipe, picked a coffee, selected a ratio and weighed everything out, then timed the brew. I kept track of all these details for every single brew. I included notes on the mistakes I made like pouring in too much water and what to change for the next brew. I made note of what I tasted (though my tasting skills are basic, too strong, too bitter etc are easy enough to assess), what I liked and what I didn’t like, then I considered what step in the process to change for next time. I no longer relied on memory.
I did not do everything to plan. It took time and practice to get the process correct.
The key was making, tasting, recording the results and then applying the concepts I had learnt to make an educated decision on how to improve my next brew.
As I went through the process, I learnt that I enjoyed a well brewed light roast, and that I’m not a fan of dark roasts. Not in the French press at least.
Sticking with my French press process for consistency
I do the following key things:
Calculate my coffee grounds and water requirements.
Weigh my grounds first and then my water when pouring.
Use a timer.
Preheat the beaker, my mug and the milk as needed.
Wait a little bit once the water has boiled before using it.
Agitate the wet grounds during the bloom phase.
Adjust for each new bag of coffee I use.
Getting proficient and familiar with these steps allowed me to alter them as needed. But that’s influenced by the taste of the brew and by all of my test brews over a period of time that cemented those concepts for me.
If you’d like to see my recipe and steps check out my article: An everyday French press recipe.
If you’d like to see my recipe and steps, and some troubleshooting tips, check out my article on that - Guide to Troubleshooting your French Press Brew.
I hope that this article has provided you with either new information, or a new way of thinking about what you know about coffee. Happy brewing.
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