Pour over coffee has been trending in recent years, taking over many cafés and whetting the interest of coffee drinkers. What exactly is "pour over coffee?" Let us explain the basics.
The so-called "pour over coffee" is the practice of pouring right-amount, right-temperature water steadily onto pre-ground coffee in a filter cup or on filter paper under one atm to make coffee. The grain size of coffee powder, water temperature, the way of pouring, and brewing time all have effects on the flavor of the extracted coffee, so it is a brewing method that is highly specialized in skill and coffee expertise.
The principle of extraction in pour over coffee is made up of three physical mechanisms – infiltration, dissolution, and diffusion – between water and coffee powder. The process is as follows:
The first-round pouring only takes a little water. It is aimed at simply wetting the coffee powder to accelerate carbon dioxide emission in the coffee powder (hence the enlargement of coffee powder heap). Carbon dioxide blocks the contact between water and coffee and prevents water from extracting the substances in coffee cells. This will render coffee flavor incomplete.
After carbon dioxide is gone, the second-round pouring begins. Water will dissolves 1/3 of the soluble particles in the coffee (the other 2⁄3 is insoluble fiber), including hundreds of substances, such as caffeine, acidity (sour taste), aroma, fat, sugar (sweetness), and carbohydrate (bitterness), that structure a coffee’s distinct flavor.
The dissolved particles leave the coffee powder and diffuse into the water and become the coffee liquid in our pot that is full of aroma, sweet and bitter taste and rich fat. It is delicate, rich and has varied flavors.
Now that you have understood the characteristics and principles of pour over coffee, there may be more different feelings and enjoyment when brewing and tasting coffee next time!