Steaming Coffee with a Purple Clay Pot?! Chinese-Style Extraction Has Made Another Breakthrough!

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Water-Bath Coffee Extraction: A Traditional Brewing Innovation

At this time last year, a coffee shop in Shanghai sparked heated discussions among netizens by using a "water-bath" method to extract coffee.

The Science Behind Water-Bath Extraction

The principle of water-bath extraction involves placing coffee powder and liquid at a certain temperature in high-temperature water for prolonged simmering. By controlling the coffee grind size and extraction time, coffee particles release pleasant, mellow flavor compounds within the water-bath container.

Although it involves high-temperature simmering, the temperature inside the container remains within a certain range, effectively controlling the release of bitter compounds from coffee particles and ensuring the extracted coffee tastes rich and mellow with a smooth, non-bitter mouthfeel.

Innovation in Coffee Brewing Methods

When this method emerged, some netizens considered it a gimmick, while others noted that Japan has flannel-filtered coffee, Italy has pressurized espresso extraction, and China applying traditional cooking techniques to coffee extraction is a positive development. After all, coffee extraction is continuously being innovated and changed.

After Coffee Workshop published related articles, fans in the comment section suggested: "You can also steam coffee in a steamer basket." Coincidentally, while browsing online, our editor saw a netizen sharing a very Minnan (Southern Fujian) style of coffee brewing at the Xiamen Coffee Festival—steaming coffee in a purple clay teapot!

— Martin马儿六

The preparation method is as follows: Place 18g of coffee ground for pour-over into a small purple clay teapot, with a powder-to-water ratio of 1:5. You can also add ginseng/angelica/bergamot (optional), then steam for 30-40 minutes. Finally, filter with paper and add appropriate amount of water before tasting.

— Martin马儿六

Benefits of Slow Extraction in Purple Clay

This method actually shares similarities with water-bath extraction, namely low-temperature slow extraction. Although the temperature inside the steamer is very high, the coffee temperature in the pot rises much more slowly than direct boiling. At the same time, there's very little water for coffee extraction, so the coffee liquid quickly reaches saturation, preventing the extraction of bitter and unpleasant flavors in later stages.

— 咖啡决定

Additionally, purple clay teapots themselves have the ability to absorb compounds that cause unpleasant flavors in coffee, effectively reducing the bitterness of coffee!

The Science Behind Purple Clay's Benefits

Previously, a company under Amazon Japan developed a device that looks like a teapot on the surface but is actually used for brewing coffee. The pot body uses the "Tokoname-yaki" (also known as Japanese purple clay) firing technique with 1000 years of history, characterized by using clay with high iron content. The firing process doesn't use glaze, and after firing, it's polished to present a smooth, bright surface.

Because no glaze is used, the porous and water-absorbing properties of the ceramic itself are preserved, effectively absorbing compounds that cause unpleasant flavors in coffee. Although Chinese purple clay differs from the materials used in Tokoname-yaki, it achieves the same effect of reducing bitterness while preserving the aroma and flavor of tea/coffee.

Understanding Coffee Bitterness Compounds

Most bitterness in coffee comes from two compounds: chlorogenic acid lactones and phenylindanes. Both compounds are produced during the roasting process as chlorogenic acid breaks down. Light to medium-roasted coffees mainly taste bitter due to higher chlorogenic acid lactone content in the beans. As roasting time extends and beans become darker, they contain more phenyl compounds. The higher the phenylindane content, the sharper and more persistent the bitterness in coffee.

According to experiments conducted by multiple netizens who discreetly used purple clay teapots when their parents weren't looking, it has been proven that the structure of purple clay teapots themselves can effectively absorb these uncomfortable-tasting compounds, making the coffee's mouthfeel cleaner.

The Future of Coffee Innovation

Coffee brewing doesn't just change within established brewing methods—creative coffee preparation isn't limited to changing flavor ingredients. Innovation requires stepping outside existing frameworks and doing something truly distinctive to be considered genuine innovation.

Image source: Internet

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