How does turbulence and agitation affect the flavor of hand-brewed coffee? How does stirring affect coffee extraction?

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Hand coffee is really good! You can watch the flow of water stay gracefully, while a good coffee is like a crystal-clear liquid, and the best thing is that anyone can make it at home.

But it looks great but it is not as simple as it seems, in addition to the common factors such as water temperature, powder-to-water ratio, grinding thickness and so on, there are also causes of disturbance and agitation. So what is disturbance and agitation? What do experts say about the disturbance and stirring of hand-brewed coffee? And the most important thing is, does it really taste better?

What is agitation?

Let's start with the basics, we all know that there are two procedures in the process of hand brewing: first, soak the coffee powder with a small amount of hot water and wait for about half a minute to achieve the effect of steaming; second, pour the remaining water into the coffee powder so that the coffee can slowly drip into the receiving container.

But there is also agitation or disturbance in the process, just like when you are busy, your brother and sister show up next to you, but it is not so negative, and in fact, you are playing the role of brother and sister.

To put it simply, stirring and disturbing in the cooking process is a mild interference, there are many forms of stirring, each has its own reason, before we see how to stir, let's see what you want to achieve.

We're all trying to get the coffee to taste good, which means we need to get consistent extraction results, and if the extraction rate varies from one part of the cup to another, you can't manipulate or replicate the flavor in the cup. Your coffee will have a mixture of under-extracted (sour) and over-extracted (bitter) flavors, but it will also contain well-extracted flavors, such as sweetness and good taste.

What can be achieved by stirring?

A common issue in hand-brewed or spaghetti coffee is the channel effect. Water always flows to places with less resistance, so if the coffee powder is not stacked or soaked evenly, the water will create a channel in the coffee powder. this will make more coffee near the channel extracted.

The channel effect can be caused by too fast or unstable water injection, for example, this leaves a high and dry coffee powder wall on the filter paper, which cannot be extracted. Some people also use drip water injection (using a small amount of water several times instead of long water injection), which can avoid the emergence of such powder walls.

In other words, stirring will disperse the coffee powder and ensure the uniformity of the extraction, which is not the only reason for maintaining a consistent extraction. If you want the coffee to taste the same every day, try standardizing your brewing parameters, including powder quantity, water temperature, brewing filter, water injection path and speed, water quality, grinding thickness and brewing time, etc.

How to stir hand brew / drip coffee

There are several ways to stir, the most common of which is stirring, which is recommended by some coffee experts, such as Matt Perger and Scott Rao, a well-known barista. You can stir the coffee powder directly after steaming, or at the beginning of steaming, or in the back section of steaming.

You may also have heard of spoiler, which means that at the end of the injection, pour the water into the edge of the filter cup and flush the top coffee powder into the coffee liquid from the edge.

Agitation can also take several forms, such as drips of water, side swirls, controlling the flow rate and amount of water, and so on.

What techniques do experts use?

Matt Perger and Scott Rao mentioned above, let's see what methods they use here. When Matt Perger won the 2012 World Cooking Competition a few years ago, he shared a film about the cooking of V60 filter cups. You can break down his movements, notice that he stirs vigorously after steaming, then control the direction of the hand (the expanding concentric circle), use these forces to avoid the formation of the powder wall, cook rhythmically, and pull up and gently shake the filter cup before the end to make the powder bed horizontal.

He can also be seen in the film using Rao Spin, which takes its name from Scott Rao, which allows the water to rotate in a spiral during cooking, thus allowing the water to drop more evenly.

Even though Rao wasn't the inventor of the technology, it was developed in his work, and he supports it. "it minimizes the channel effect at the end of cooking and creates a flat powder bed at the end of each cooking," Rao said. "it's a great technology. I wish I had invented it."

You can also create a Rao Spin by gently shaking the filter cup, which is shown in the following seven-second motion picture taken by Scott Rao.

Rao is also very supportive of stirring coffee at the end of steaming and brewing, just like Matt Perger.

So how do we apply it?

You can try all of the above, whether you are a barista, a coffee lover or just a beginner, stir while brewing, try not to stir in the next round, and then test the differences yourself. or share it with friends and show it to your guests.

Find out the differences, taste the subtle changes in the coffee, and change the grinding thickness and brewing methods, and then find the best way to copy to keep the brewing results consistent.

The best thing about the third wave of coffee is the experiment, in which you do some stirring experiments to see if this method is suitable for you.

Translated from Perfect Daily Grind

Translated by Cheng Zhen Coffee

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