How Water Affects Coffee Extraction

Coffee? Water? Super Effective!

 

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Water is the soul of coffee.

Good coffee cannot exist without the right water volume, right water temperature, right filtered water, alkaline/acidic water, etc. In this post, we will talk about the two most important factors: water volume and water temperature.

 

What is the right ratio?

There are two major home brewing methods, which are filtration and immersion. Filtration is when the water flows through the coffee grind, then through a filter. For filtration coffee, the usual golden ratio is 1:16. For every ounce of coffee grind used, you want to use 16 ounces of coffee. However that isn't the magical do it all formula. 

Here are some coffee to water ratio depending on the extraction method:

Coffee Brewer: 1:16   Medium fine grind.
Pour Over: 1:14   Medium grind.
French Press 1:10  Coarse grind.

This is assuming the right grind size.
Finer grind will always brew stronger and bitter, while coarser will always be too weak.

 

What is the right water temperature? 

The traditional hot brewing temperature ranges from 195~205 F (95 C). In case you guys are wondering, that is almost right before, or a little after water boiling. Anything cooler will increase chance of under extracting, and anything over will increase chance of over extracting and burn the cell wall. If the water is hot, you're extracting the flavor. If the water is cold, you're rather neutralizing the content of the coffee bean and the water (reverse osmosis that you learned in biology 101).

Cold Brew was, and still is, a special drink because it uses cold water (mind blown!). Instead of using heat to extract the flavors out, it uses time; it uses reverse osmosis to find have the flavor and the caffeine out of the grinds to the water. Because of the nature of reverse osmosis, it is hard to over extract when a point is reached and only extracts sweet, acidic, and other nice flavors, and not the harsher flavors. It also has more caffeine contents because it gives caffeine plenty of time to be extracted into the water.

 

This graph shows the sequence of the extraction during each brew. Coffee's natural acidic flavor comes out, then sweetness, then bitterness (note that the bitterness of the coffee that we are talking about is not from dark roast coffee, but that comes from over extraction).

This graph also explains why old and stale hot cup of coffee goes bad much faster than a cup of cold brew or ice coffee. Because micro grinds in each cup of coffee are constantly being brewed, hot coffee will have much shorter good coffee time than the iced. It definitely aren't the coffee fairies flying about spoiling your coffee after certain time. (We got your back coffee fairies.)

Please feel free to leave a comment, questions, other coffee talks! We love coffee talks and in order to provide the world with better coffee, we would try anything!