When we make coffee, we mostly discuss coffee beans, production methods, flavor and other issues, but few people care about the thing with the largest proportion in a cup of coffee – water.
Everyone knows that water is the most abundant component in the human body.
The same is true for coffee. 98% of a cup of coffee is water (espresso is a little less, 92%). It can be said that the materials affect the taste and taste of coffee, not only the quality and source of coffee beans, but also the quality of water to a certain extent.
Before understanding the impact of water quality on coffee, let’s share a few concepts. That is what we call “water” and “water quality”.
“The simplest oxyhydrogen compound, chemical formula H2O, is a colorless, tasteless and odorless liquid. Under standard atmospheric pressure (101325 PA), the freezing point is 0 ℃, the boiling point is 100 ℃, and the maximum density is 1g / ml at 4 ℃.” – this is the explanation of the word “water” in the Chinese dictionary.
However, we all know that the colorless, tasteless and transparent water we are exposed to is not as “nothing” as we seem. There is a saying in China: the water quality in the north is hard and the water quality in the south is soft. This is the difference caused by the hidden things in the water. A large number of solutes and solids determine the “water quality”.
What determines the soft and hard water quality is the amount of minerals dissolved in the water. In fact, it mainly refers to the amount of magnesium ions and calcium ions.
Hard water refers to water with high content of calcium and magnesium compounds; Soft water, on the contrary, is water that contains no or less calcium and magnesium compounds.
Do these two kinds of water have a great impact on the taste of coffee? The answer is, big.
Christopher h. Hendon (left), a chemist at MIT, discovered the importance of water in coffee after overhearing a conversation between two frustrated baristas.
“They found a problem when drinking coffee: coffee tastes good and bad,” hunton told business insider. Although this is a frustrating mystery for a coffee shop with strict standards, it “is an interesting question from a chemical point of view,” hunton said.
Calcium and magnesium in water are metals dissolved by charged particles (Ca2 + and Mg2 +). Positive charge is very important because most flavor compounds in coffee are negatively charged when dissolved in water, which means that they will be attracted by positively charged metal ions. Therefore, water with high calcium and magnesium can retain more complex taste of coffee.
So, for coffee making, the higher the content of calcium and magnesium ions in the water, the better? Nor is it.
Too much calcium will weaken the bitterness of coffee, while too much magnesium will weaken the astringency and bitterness of coffee. Therefore, some coffee lovers specially buy mineral water to make coffee. I don’t know if it is cooked, it may be self defeating.
On the contrary, there are also friends who specially buy distilled water to brew coffee. Their original intention is to try whether the most “pure” water can keep the most original taste of coffee. In fact, the result is a waste of good coffee beans and a cup of plain coffee. “Pure” water is not suitable for making coffee. Due to the lack of minerals in the water, the taste of the water itself is lower, and the coffee often tastes stiff and lacks a sense of hierarchy.
In this way, we can see that the water for brewing coffee needs to contain certain minerals to help the formation and emergence of specific coffee flavor, but too many minerals will have adverse effects.
So let’s take a look at the impact of the pH value of water on making coffee? In the natural ideal state, the pH value of water should be 7, that is, neutral. However, due to different sources and treatment methods, the water we are exposed to will float between 6 and 9, which makes the water acidic or alkaline, thus affecting the production of coffee. In short,
Acidic water is not conducive to extraction, but it itself is conducive to flavor. (in addition, the corrosion of sour water to equipment is also a problem.)
Alkaline water is conducive to extraction, but it is not conducive to flavor.
So when we choose the water used to make coffee,
Appropriate mineral content, i.e. soft water; Water with pH close to neutral (7); You can keep the balance of coffee taste as much as possible.
Do not choose mineral water, distilled water, or acidic and alkaline water.
Buy ordinary purified water on the market.
In fact, if you make coffee at home, another simple way is to use filtered water. However, China has a vast territory and the water quality varies from region to region. You can adjust the filter according to your own situation. The same is true for coffee shops. The water quality will indeed affect the taste of coffee. If you try to make some adjustments on this point, I believe you will get more satisfactory coffee.
Of course, for explorers who love experiments, you can try to make coffee with three kinds of water (distilled water, purified water / filtered water and mineral water) and try the differences between tastes. This intuitive way is to help you remember which water is more suitable for making coffee.