What's the difference between the extraction of coffee and tea? why is coffee ground tea but directly soaked?

Pu'er Tea [Photo: Vicky Wasik]

The main difference between where I keep my tea set and where my coffee equipment is located is scale. My coffee cabinet is constantly filled with products-ceramic cones, various grinders, Danish immersed neoprene pans and so on. On the other hand, my tea drawer has only three tea sets-a glass jar with a filter, a clay pot with a handle with a fine sieve and a covered ceramic bowl called Geiger-all of which depend on the same basic method: soaking.

Why is the style of tea so consistent, while there are different coffee brewing products on the market? The simple answer is that tea production in China, Taiwan and Japan is a thousand-year-old practice, with a long-standing quality concept, suitable for agriculture, processing and preparation. In a word, tea has been solved very well. By contrast, most of the coffee businesses live in Central America, South America, East Africa and Indonesia, mainly to North American and European markets. This is an export crop whose consumers have long had a low cost and high caffeine priority. It is only in the past few decades that the professional coffee industry has been able to adjust new coffee brewing methods every year at every stage of every process, from farm to coffee. )

Coffee plants are grown in Zimbabwe. [photo: Ray Mwareya]

However, there are scientific reasons behind these methods of brewing coffee and tea. Most of this boils down to the composition of the plant substances discussed-roasted and ground seeds of coffee fruits on the one hand, processed and dried leaves of tea trees on the other, or another kind of tea trees, taste, texture and fragrance, we try to get every answer.

Roasted coffee contains nearly a thousand flavor compounds. About half of them are aromatic hydrocarbons, mainly produced during roasting. The other half is a soluble solid (soluble substance for short), which dissolves into the drink when you add hot water. In a wide range of soluble categories, we can focus on several main types: fruit acid; fructose; caramel; and a group of 40 to 50 dry bitter plant compounds. The concentration of each coffee is determined by the type of plant from which the coffee comes, the way and where it is grown, and the way it is processed and roasted. Brewing coffee is essentially a controlled extraction of soluble matter, each of which dissolves at a different rate.

Coffee powder in French newspapers [photo: Nick Cho]

Imagine that you are six years old and want to make a glass of lemonade and sell it to your neighbor. Without much experience, you start with a pot of water. Once you squeeze in the lemon juice, it will immediately dissolve and dissipate, as well as all the fruit acid and sugar. Then pour in the sugar, sink to the bottom, and take some time to dissolve completely. This is similar to caramelized sugars in coffee-they are larger molecules that are harder to break down, but eventually break down. If you adorn the pitcher with lemon slices, you may find that over time, some unnecessary bitter flavors (the ones found in most plants) will begin to seep into the mixture. but these flavors also take a while to completely dissolve and combine with the rest of the drink.

A similar process occurs when we brew coffee, and taking into account the behavior of coffee ingredients, we can control the taste of finished cups by affecting the rate at which soluble substances dissolve. We played with five main variables: the ratio of coffee to water, the size of coffee grounds, brewing time, water temperature and the degree of agitation in the extraction process. There are many tutorials on how to extract coffee. But only by discussing what happens when we add hot water to ground coffee can we understand why tea brews are different.

It is important to note that coffee is only about 30% soluble by weight; the other 70% is cellulose and plant fiber. When we grind coffee, we are making tiny, jagged geometry out of cellulose and fiber and weaving it with soluble materials. In dripping brewing, water enters through these jagged surfaces, saturates the particles, dissolves what it can dissolve, and then rinses off with later water. Immersion brewing works similarly, but mainly relies on infiltration to move dissolved coffee particles from the inside of each coffee grounds to the rest of the coffee brewing.

Pourover coffee. [photo: Nick Cho]

Coffee grinds are porous; their structure looks a bit like a sponge, with only a few tunnels passing through it. The extracted soluble matter is embedded in the walls of those small tunnels. In some ways, when the water began to chase them through the tunnel, the extraction process looked like the scene of harvesters at Indiana Jones and Doom temples. The larger the coffee particles, the longer the mine car tunnel system inside the coffee particles, and the more time it takes for water to pass through, thus extracting the soluble matter. If you can imagine that tiny versions of Indy,Willie and Short Round are being chased by brewing water in coffee granules, don't worry.

Controlling all five brewing variables means that you can extract fruit acid, fructose and caramel from the coffee bed, that is, the quality of coffee grounds precipitated together in the filter, but before extracting and drying, the sowthistle plant material. You can try any type of brewing method-dripping, soaking, a combination of both-as long as your brewing variables are balanced, the required flavor materials will be extracted into your cup.

A close-up of the camellia sinensis plant is in Taiwan. [photo: Max Falkowitz]

Tea is a different story. The product of camellia plant is a little more chameleon, because each kind of tea style starts from the same leaf. In other words, like coffee, what we taste in tea can be divided into several main categories: polyphenols, amino acids and essential oils.

Polyphenols include a group of different plant compounds, such as flavanols (especially catechins), that contribute to the body and structure as well as a general blueprint for tea flavor profiles. They are also responsible for the pain of tea. Amino acids are the cornerstone of protein, with texture and salty characteristics, essential oils produce fragrance and more delicate and complex aroma. Polyphenols dissolve and extract quite quickly, while amino acids take more time, but essential oils ring here: they are actually insoluble in tea because the oil is insoluble in liquid. During the immersion process, we need enough time to decompose the cellular structure of the water. What makes essential oils released to brewed tea?

This does not mean that all teas are the same: when the tea is processed, the building blocks we taste will change dramatically. The polyphenols in the leaves will provide more "green" flavor for the tea, while the oxidized polyphenols will develop into heavier, deeper flavor categories. Green tea producers try to preserve more of these crude polyphenols by stopping oxidation immediately after picking. Oolong tea processing usually involves bruising and uneven oxidation of leaves to establish complexity; black tea production, leaf crushing usually exposes the leaves to a longer oxidation period, producing richer colors and strong flavors. Many tea producers will also adjust their agricultural practices to change the way chemical compounds are built inside the leaves. Nitrogen-rich fertilizers trigger more amino acid production in leaves. High-altitude farmland and harvest periods allow leaves to develop high essential oil content.

Four varieties of tea are cold brewed. [photo: Vicky Wasik]

But almost all kinds of tea, from kabusensha tea in Japan to alpine oolong tea in Taiwan, need to be soaked. The tea needs to be soaked because it gives up the ghost way.

In the final stage of processing high-quality tea, the leaves are shaped, burned and dried. This can be done in many different ways, but, with a few exceptions, high-quality tea is usually prepared, the leaves are intact and rolled into tight spherical or fine stripes. In order for the water to fully penetrate into the structure of the tea, it takes time and saturation. The leaves need to unfold and you need to expose the surface of the tea to the water soaked in ​​.

After several times of oolong tea, the leaves spread out completely. [photo: Vicky Wasik]

The easiest way to achieve this is always through soaking, which means that soaking is the core of the process, although different preparation methods are used depending on the style of the tea. Gaiwans- small lid bowl-designed for high temperature, high dose, short time soaking tightly rolled global oolong tea. The larger standard teapot is suitable for thin striped black tea and Chinese green tea, which is steep for up to two to three minutes, leaving plenty of space and time for the leaves to unfold lazily. And handle the Japanese clay kuusu basin so that it is ready to use cold water and fast soaking time, while the handle allows gentle, rocking perfusion to quickly drain the infusion between the teapots.

At the same time, polyphenols and amino acids can be extracted with dripping brewing process, but tea needs constant contact with water to make the essential oil completely released. Dripping uses a constant rinse action and may not fully absorb the taste of the tea we want. In addition, the use of paper filters can immediately eliminate 1/3 of what we usually taste from the flavor characteristics of tea, because essential oils and tiny particles are trapped in the fibers of the filter.

Looking at the various ways of preparing tea, they are all so similar, and there have been so few changes in each design in the past hundred years. The tea-soaking process does not often respond to crazy things that are found to be possible; it starts on the farm, focuses on what tea can offer, and strives to achieve a specific flavor profile of each step. Sometimes, when I look at my Danish coffee maker, or the Aeropress coffee machine in my refrigerator, I wonder if the coffee industry can take more clues from the world to the tea tradition.