Welcome Note

Hello hello! Welcome back to the second edition of the The Retired Barista. Be sure to follow me on all social platforms @larsmillermedia for more daily content.

This week I break down the science behind a great cup of coffee. What all goes into the perfect cup and how modern brewing practice align with ancient brewing practices more than we would assume. I also look into some recent news in the speciality coffee industry and what I am drinking and enjoying recently.

P.S. You can find me as @LarsMillerMedia across all social platforms. Drop by and say hi—I'd love to hear your coffee stories!

News Roundup

• With Green Climate Fund Backing, Conservation International Launches Aroma Coffee Project - Conservation International is teaming up with the Green Climate Fund to launch the Aroma Coffee Project, an initiative aimed at promoting sustainable coffee production in tropical regions. The project focuses on climate resilience, biodiversity, and improving farmer livelihoods.

• Farmer Brothers Coffee Makes Two Key VP Appointments - Farmer Brothers Coffee has announced the appointments of two new Vice Presidents to strengthen its leadership team. The company aims to leverage these changes to drive growth and enhance its operational efficiency.

• Announcing the Second Annual Sprudge Design Award Winners - The winners of the second annual Sprudge Design Awards have been announced, highlighting outstanding design in coffee spaces, packaging, and equipment. This year’s winners showcase a blend of innovation, aesthetics, and functionality across the coffee industry.

• And Coffee Loved David Lynch Back - David Lynch’s love affair with coffee continues, as his influence extends into creative coffee culture. This piece explores Lynch’s contributions to coffee branding and his ongoing role as a beloved figure in the industry.

The Science of the Perfect Cup: What 200-Year-Old Research Can Teach Us About Better Coffee

I've fielded countless questions about brewing the perfect cup of coffee. While modern coffee culture often focuses on the latest gadgets and trending techniques, I recently discovered something fascinating: many of our "cutting-edge" brewing principles were actually documented by a brilliant scientist over 200 years ago. His meticulous research not only validates many modern brewing methods but also reveals some forgotten wisdom we'd do well to remember. What's most remarkable is how this historical figure approached coffee brewing not just as a culinary art, but as a scientific pursuit worthy of rigorous study.

Defining "The Best" Coffee - A Scientific Approach

The question of what makes coffee "good" has puzzled brewers and scientists alike for centuries. While today's coffee culture often focuses on subjective taste preferences and scoring systems, our historical scientist took a refreshingly objective approach. Instead of relying on personal taste, he focused on something measurable: aroma retention. Through careful observation and experimentation, he discovered that when coffee loses its "peculiar aromatic flavour," it loses "all that was valuable in it."

This wasn't just personal preference or coffee snobbery - he conducted numerous experiments to prove that aroma loss directly corresponded to a decline in coffee quality. Think about walking into your favorite coffee shop. That incredible aroma that greets you? While it might seem like a positive sign, our scientist would argue it's actually indicating coffee quality being lost to the air. Every molecule of coffee aroma you smell in the room is one that won't be in your cup. This simple but profound observation forms the foundation of his entire approach to coffee brewing.

The Temperature Game: More Complex Than You Think

Temperature's role in coffee brewing extends far beyond simply "hot water extracts better than cold." Through extensive experimentation, our scientist uncovered a complex relationship between temperature and coffee quality that still influences brewing today. He discovered that boiling water proved optimal for extraction, but the real insight came from understanding why. It wasn't just about extraction efficiency - it was about temperature stability and its effect on aroma retention.

When brewing coffee, temperature differences create convection currents within the liquid. These currents act like tiny elevators, actively transporting aromatic compounds out of your coffee and into the air. The greater the temperature difference between your coffee and its surroundings, the more aggressive these currents become. This explains why coffee seems to lose its charm so quickly when served in a cold cup or left to cool on the counter.

The scientist's experiments with water temperature weren't limited to hot brewing. He also explored cold extraction methods, finding them "inferior" when using traditional brewing times. However, his observations about temperature stability and aroma retention remain relevant even in modern cold brew methods. The key insight wasn't just about hot versus cold, but about maintaining consistent temperatures throughout the brewing process.

The Vessel Revolution: Not Just About Keeping Coffee Hot

Perhaps the most fascinating aspect of this historical research involves the impact of brewing vessels on coffee quality. The material and design of coffee vessels played a crucial role in maintaining coffee quality - far beyond simply keeping it hot.

Research found that gilded ceramic vessels outperformed all other materials, extending heat retention by up to 50% compared to their non-gilded counterparts. This wasn't just about temperature maintenance, the gilding actually helped reflect heat back into the coffee, reducing those problematic convection currents that steal away precious aromas. Plain ceramic vessels performed well but couldn't match their gilded counterparts. Surprisingly, pure metal vessels, despite their excellent heat conductivity, proved less effective at maintaining coffee quality over time.

Modern double-walled vessels and vacuum-insulated containers operate on similar principles, though using different materials and technologies. They create a stable temperature environment that helps preserve those volatile compounds that give coffee its complex flavor profile.

The Physics Behind Perfect Coffee

Understanding the underlying physics of coffee brewing helps explain why certain practices consistently produce better results. When hot coffee encounters cooler air or surfaces, it creates a temperature gradient. This gradient triggers thermal convection - a process where hot liquid rises while cooler liquid sinks, creating circular currents within your coffee. These currents don't just mix your coffee; they actively accelerate the loss of volatile compounds that give coffee its distinctive flavor and aroma.

Coffee contains hundreds of volatile aromatic compounds, each contributing to its complex flavor profile. These compounds are extremely sensitive to temperature changes and easily lost through evaporation. The stronger the convection currents in your coffee, the faster these compounds escape. This explains why coffee served in a pre-heated cup tastes better longer than coffee served in a cold cup - it's not just about temperature, but about minimizing the convection currents that strip away flavor.

Modern Applications of Historical Wisdom

While we might not all have access to gold-plated coffee vessels, the principles our scientist discovered can be applied to modern brewing methods in surprisingly practical ways. Today's coffee equipment often unconsciously incorporates these historical insights about temperature stability and aroma retention.

Consider the modern thermal carafe. Its double-walled construction creates an insulating layer of air or vacuum that serves the same purpose as our scientist's gilded ceramics - maintaining temperature stability while minimizing those destructive convection currents. Even the ceramic mugs we favor in specialty coffee shops aren't just about aesthetics; they're actually following our scientist's observations about material properties and heat retention.

The way we approach brewing has evolved too. Modern pour-over techniques, with their careful attention to water temperature and controlled pouring patterns, align perfectly with our scientist's findings about minimizing agitation and maintaining temperature stability. Even the recent trend toward temperature-controlled kettles reflects his emphasis on precise temperature management throughout the brewing process.

The Great Cold Brew Debate Revisited

While our historical scientist dismissed cold brew as "inferior," his experiments were based on short extraction times typical of hot brewing methods. Modern cold brew practices tell a different story, and understanding why reveals even more about coffee chemistry. When we brew cold for 12-24 hours, we're actually working with an entirely different set of chemical reactions.

Cold water extracts compounds from coffee more slowly and selectively than hot water. This explains why cold brew typically presents with less acidity and bitterness - these compounds simply aren't extracted as readily at lower temperatures. However, the longer steeping time allows for full extraction of other desirable compounds, creating a smooth, full-bodied brew.

Interestingly, his principles about minimizing agitation and maintaining temperature stability apply equally well to cold brew. Many modern cold brew systems incorporate these ideas, using stable temperatures and gentle extraction methods to produce consistent results. The key difference is that we're now working with time as our primary extraction variable rather than temperature.

Practical Applications for Better Coffee Today

Understanding these historical principles transforms how we approach daily coffee brewing. Rather than viewing preheating as an optional step, we can recognize it as crucial for maintaining temperature stability throughout the brewing process. This means warming not just your brewing vessel but also your filters, cups, and any other equipment that will contact your coffee.

Water temperature management becomes more than just hitting a target number on your kettle. It's about maintaining that temperature throughout the entire brewing process. This might mean adjusting your brewing method based on ambient room temperature, using a heat-retaining vessel for longer brews, or even considering how the temperature of your grinding equipment might affect your final cup.

The way we handle our coffee after brewing matters just as much as the brewing process itself. Serving immediately isn't just about having hot coffee - it's about preserving those volatile compounds that contribute to flavor and aroma. When immediate serving isn't possible, using proper thermal storage containers becomes crucial for maintaining coffee quality, not just temperature.

A Personal Reflection and Looking Forward

As someone who's spent countless hours brewing coffee, I find it humbling that many techniques we consider "modern" were actually discovered centuries ago. It reminds me that great coffee isn't about having the latest equipment - it's about understanding and respecting fundamental principles that have remained unchanged for centuries.

The next time you brew coffee, try viewing the process through scientific eyes. Notice how the aroma fills your kitchen and consider whether those precious volatile compounds might be better preserved in your cup. Think about the temperature stability of your brewing setup and how you might improve it. Most importantly, remember that while coffee brewing has evolved tremendously over the centuries, the basic principles of what makes a great cup remain remarkably consistent.

Whether you're using a simple pour-over or a complex espresso machine, these fundamental principles of temperature stability, minimal agitation, and proper extraction continue to guide us toward better coffee. By understanding and applying these principles, we can all brew better coffee, regardless of our chosen method or equipment.

Gear, Roasters, and Cafes I am Loving Right Now

Roasters

• Tinker Coffee - Ethiopia Hamasho

  • This coffee has been phenomenal. The fruitiness is subtle but very prevalent. The lavender floralness balances out the fruit sweetness and in my lattes pairs amazing with the milk.

• Black & White Roasters - The Future

  • This has been a delight both as a shot, paired with milk, but it has really shone when brewed on my V60. The brightness of the coffee and the lightness has been a such a treat. Black and White Roasters never disappoints.

• Prodigal Coffee - Buena Vista Pink Bourbon

  • I FLEW through this bag. I couldn’t quit it. Hibiscus is one of my kryptonites. I LOVE it. This coffee smelled amazing in the bag, smelled amazing ground, even more so brewed, and then finished it all off by tasting even better. Just as it is described on the bag is what I got. It was bright, bold, and juicy as hell. Highly recommend.

Gear

• Coffee Alive Extract Chilling Steel Ball

Cafes

• Third Place Cafe: Boca Raton, FL

• Mane Coffee: Boca Raton, FL