Pu’er Coffee

 When it comes to coffee extraction—whether it's espresso or pour-over—there’s one thing you simply can’t avoid: the filter paper . This small sheet of paper has quietly evolved over the past few years alongside the technological development of specialty coffee. In fact, its evolution has been so dramatic that the word “crazy” might not be an exaggeration. This “craziness” includes innovations in materials, upgrades in functionality, and of course, some pretty crazy price tags as well—haha. Today, I’d like to talk about why filter papers in coffee extraction keep evolving. What exactly are people pursuing when they aim for the ultimate cup of coffee? And what role can filter paper play in shaping the final result? Let’s dive into the “crazy evolution” of coffee filter papers. Different filter papers vary in density, thickness, structure, and permeability , and these factors directly determine the flow rate . Flow rate, in turn, affects coffee extraction, flavor, and mouthfeel. ...

 Not long ago, I came across a video online showing someone roasting coffee beans using a traditional hand-cranked popcorn machine—the kind we used to see on the street when we were kids, the one that would suddenly go BOOM behind you without warning. Honestly, that thing alone was childhood trauma for many of us. Of course, when used for coffee beans, there wouldn’t be that final explosive step. From a purely theoretical standpoint, this method does seem somewhat feasible. Still, I find it extremely unreliable in practice. So today, I want to take a closer, more serious look at this idea. Traditional hand-cranked popcorn machines are actually somewhat similar to hand-mesh coffee roasting. Both rely on an external heat source—usually an open flame—to heat a sealed metal drum, allowing the contents inside to undergo physical and chemical changes. By manually cranking the handle, the beans can be agitated so they heat more evenly, reducing the risk of localized scorching. In princi...

 Among coffee professionals, there is a group of true “behind-the-scenes heroes.” They may not be great talkers, many of them lean toward being introverts, and they tend to work with rigor, precision, and an almost obsessive attention to detail and data. In my eyes, they are among the most technically skilled people in the coffee industry: coffee roasters. If I had to sum up their work in one sentence, it would be this: “I am not the creator of flavor—I am a carrier of flavor.” They are the ones who allow every coffee drinker to experience the unique character and terroir of different origins. In that sense, roasters play an irreplaceable role. Looking back, I’m surprised that despite nearly ten years of daily writing, I’ve never written a dedicated piece about coffee roasters. Recently, as I’ve been testing beans from different roasters, I’ve found that I can genuinely sense their thinking through their roasting styles. This quiet, almost invisible form of dialogue has deepene...

 The first time I tried a Dirty coffee served in an ultra-low-temperature ice cup was back in 2023, at UNCLE SHU Coffee in Binjiang, Hangzhou. It was my first real encounter with that striking “hot-meets-cold” contrast, and the experience left a strong impression. Dirty coffee is something most coffee lovers in China are already familiar with. It’s fairly common in cafés across Asia, yet you’ll rarely find it in Europe or the U.S. At its core, a Dirty is simple: ice-cold milk topped with hot espresso. This collision of temperatures creates a dramatic, almost theatrical drinking experience that many people love. In recent years, however, a new trend has taken things to the extreme—using ice cups chilled to −86°C to make Dirty coffee. Compared with a traditional Dirty, which usually uses milk and a cup chilled to around 4°C, a −86°C ice cup paired with espresso at roughly 65–70°C creates a temperature difference of more than 150°C. This extreme contrast delivers a sharper, more int...

 This question is something I’ve noticed quite frequently over the past year while café hopping. Of course, it’s not a new topic for me—I’ve already touched on it multiple times in previous articles. Personally, I’ve encountered it so often that I’ve almost become “desensitized” to the idea of filtering crema from an Americano. But if we take a more rational step back, the reason many cafés now promote over-extraction–style Americanos is fairly clear: they’re chasing a cleaner, more stable, and smoother mouthfeel, while trying to avoid unpleasant flavors. From my point of view, over-extraction–based Americanos and traditional “espresso + water” Americanos follow fundamentally different extraction and brewing logics. In that context, removing the crema can be a 1 + 1 > 2 kind of optimization. However, if it’s just a standard espresso shot that’s brewed normally, then filtered for crema, and only afterward diluted with water, I personally feel it would be better to leave the cr...

 I’ve talked before about “coffee on airplanes,” and anyone who’s been on a long-haul flight knows the feeling—at some point, you just want a decent cup of coffee to stay awake. Unfortunately, what you usually get onboard is instant coffee, to the point where most people have completely given up hope. For a long time, I assumed this was simply airlines trying to cut costs, or maybe a result of limited cabin space that made it impossible to install proper coffee machines. Either way, I never felt I had a truly convincing explanation. Carrying that bias with me, I eventually started digging into the topic. After looking into the details, I finally found some solid reasons that answered a question I’d wondered about for years. So today, let’s talk about why it’s basically impossible to brew fresh coffee with a coffee machine on an airplane. I’m sure many people share this professional—or at least emotional—curiosity. The idea of sipping a freshly brewed coffee at 35,000 feet sounds i...

 As coffee continues to grow in popularity, the places where people enjoy it are no longer limited to homes or cafés. Today, coffee can be made almost anywhere—yes, even in outer space. That’s right: astronauts on space missions can enjoy coffee too. This may not sound like breaking news. In fact, it became possible more than a decade ago. However, relatively few people know the story behind it. So today, let’s take a closer look at the world’s first espresso machine designed for space: ISSpresso . Back in 2015, the Italian Space Agency partnered with Italian coffee company Lavazza to develop the world’s first espresso machine for the International Space Station. The machine was named ISSpresso. In space, due to microgravity, liquids don’t flow the way they do on Earth, making something as simple as drinking coffee extremely challenging. For many years, astronauts could only consume instant coffee squeezed out of pouches—hardly a pleasant or satisfying experience. ISSpresso fund...