How to make the perfect pour-over at home? Here’s how!

There are new coffee machines every year, and this year there are more! But can high-end equipment alone improve the quality of coffee? Not necessarily! No matter what kind of equipment we use, if we don’t understand how it brews, we will never be able to brew a truly great cup of coffee.

Today, let me analyze the working principle of the most popular hand-brew coffee maker from the perspectives of physics and chemistry.

To make hand-poured coffee, you only need coffee powder, water, filter paper and a coffee pot. Simply put, the principle of making hand-poured coffee is to manually pour water into the coffee powder to extract the essence of the flavor. Although the principle seems simple, there are many difficulties in actual operation!

From a physics perspective, the production of hand-brewed coffee is divided into three steps: soaking, dissolving, and diffusion. The three steps are closely linked and influence each other.

Why is pour-over coffee different?

Unlike other brewing methods, hand brewing can continuously extract coffee powder with fresh water, so the brewing efficiency is higher and faster. But at the same time, because the water is constantly flowing, the most fully extracted part is mostly concentrated on the surface of the coffee powder. This is like frying potatoes in a pan. If you fry them quickly over high heat, the potatoes will cook quickly, but the surface will easily be burned.

In addition, using a single jet of water (the water outlet of most coffee machines is shower-type, and multiple thinner jets of water will flow out at the same time) will make the coffee warmer during brewing (the simultaneous flow of multiple small jets of water will accelerate the loss of temperature), which will also speed up the extraction rate of the coffee.

About Wetting

As the name suggests, soaking means soaking the dry coffee powder. This step is essential and crucial. You should know that coffee produces a lot of carbon dioxide when it is roasted, especially lightly roasted coffee. The carbon dioxide is still trapped in the structure of the beans and will slowly seep out over the next few weeks; deep roasted coffee releases gas faster.

When water comes into contact with coffee powder, carbon dioxide is released instantly, forming bubbles. The key is that if carbon dioxide cannot come out, water cannot enter the coffee powder. Therefore, when you start brewing, you should soak the coffee powder with enough water and let it stand for 30 seconds to release as much carbon dioxide as possible, so that the water can better extract the essence of coffee in the subsequent brewing process. Professionals usually call this step "pre-brewing".

About Dissolution

After the coffee powder is fully soaked and the carbon dioxide is fully released, the water begins to dissolve the soluble substances in the coffee powder.

The real difficulty in brewing coffee is that coffee contains not only good solubles, but also bad solubles. Fortunately, the good solubles dissolve faster, so what we need to do is stop brewing at the right time to extract the good solubles to the greatest extent while avoiding the bad solubles.

About Diffusion

Diffusion is the process by which water brings dissolved soluble substances out of coffee powder. Since the concentration of soluble substances in the cells inside the coffee powder is higher, the solution will automatically flow from the area with higher concentration to the area with lower concentration. After completing this step, the extraction of coffee is complete.

About time and parameter adjustment

Nearly 2/3 of the substances in roasted coffee are insoluble, and only 1/3 are soluble, most of which are organic acids and sugars, and some form long-chain molecules that have a bitter taste. After continuous research, people have found that the ideal extraction degree should be 19-20%, which means that if you extract 19-20% of soluble substances from coffee, your coffee taste will be perfectly balanced. If the extraction degree is higher, the coffee will become more bitter; if it is too low, the taste of the coffee will tend to be bland, lack a sense of balance, and taste extremely sour. Therefore, time is the key to determining whether the coffee taste is balanced.

In addition, we also need to pay attention to the degree of grinding of coffee powder. Usually, the particle size of coffee powder is not uniform, and the extraction rate of finer coffee powder is much faster than that of coarser coffee powder. In order to avoid this situation as much as possible, ensuring the quality of the grinder is the key.

In summary, good hand-brewed coffee requires you to strictly control the grinding degree of coffee powder, brewing ratio (water-powder ratio) and brewing time. The brewing rate depends on the grinding degree of coffee powder. The finer the coffee powder is ground, the slower the rate, and vice versa. At the same time, the total amount of coffee (i.e. the thickness of the powder bed) will also affect the extraction rate. It can be seen that there are really many things that can go wrong when making hand-brewed coffee!

Although you don’t need too much professional brewing equipment to make hand-poured coffee, the gooseneck kettle is definitely a powerful helper for you to control the water flow. The biggest difference between hand-poured coffee and brewing coffee with a machine is that you can witness the entire process of coffee brewing, so better control of the speed and direction of the water flow means that you can extract the essence of the coffee more fully and evenly.

We just mentioned that hand-brewed coffee will maintain a higher temperature during brewing, and the pre-brew process can effectively lower the overall temperature of the coffee. During pre-brew, you will let it sit for about 30 seconds. At this time, the coffee has enough time to cool down, thus avoiding over-extraction caused by excessively high water temperature.

Having said so much, let me teach you how to make perfect hand-brewed coffee at home!

Before you start, be sure to prepare a timer, or you can use the timer on your phone.

1. First of all, the grinding degree of coffee powder should be similar to that of coarse sugar (the feel of raw sugar).

Regarding the amount of grounds, the optimal amount for most hand-poured coffee makers should be 1/2 to 2/3 of the filter bowl. Too little and the water will flow too fast and be difficult to control; too much and the water will flow too slowly or even overflow. The water ratio I recommend is 60-70 grams of coffee grounds to 1 liter of water (1:16-1:14).

2. Prepare pure hot water. After boiling, the water should be left to stand for 30 seconds before brewing. The temperature should be around 207℉ (97℃).

3. Start timing, use enough hot water to fully soak all the coffee powder, and let it sit for 30 seconds before starting to brew.

4. Pour water. Pour water as evenly and gently as possible, and pour water in multiple times to ensure the overall brewing time. The height of pouring water will directly affect the water temperature. In order to prevent excessive temperature loss, pour water as low as possible.

After you stop pouring water, the coffee will continue to extract for 20-60 seconds.

Regarding the overall brewing time of coffee, dark roasted coffee should be 2.5-3 minutes, and medium and light roasted coffee should be 3-4 minutes, which includes the extraction time after stopping pouring water.

Finally, you should adjust the above parameters appropriately according to the taste of the coffee. If the coffee is too light, try grinding it finer next time; if it is too strong, try grinding it coarser.

author

Nick Cho

English original address

www.seriouseats.com/2014/06/make-better-pourover-coffee-how-pourover-works-temperature-timing.html