Samo Smrke

The Art of Intentional Extraction Most home baristas treat espresso like a black box. You put coffee in, water flows through, and you pray the result isn't a sour mess. We often overcomplicate things by obsessing over a dozen variables simultaneously. In reality, focusing on the relationship between ratio and extraction yield is the fastest path to a better cup. By breaking down the brewing process into manageable, observable segments, you can stop guessing and start making informed adjustments to your technique. Tools and Equipment Needed To perform these exercises effectively, you need more than just a machine. You'll need a reliable espresso machine with manual control, a high-quality burr grinder, and a precision scale. For the Salami Shot specifically, gather 5 or 6 identical small cups. If you want to get technical, a refractometer helps track Total Dissolved Solids (TDS), but your palate is the ultimate judge. Exercise 1: The Salami Shot This exercise illuminates the lifecycle of an extraction. Start by pulling a long shot, roughly a 1:3 ratio. Instead of letting it fall into one glass, switch the cup every 10 grams. * **The Early Stage:** The first 10g is a concentrated, syrupy "soy sauce" of acids and fines. It’s often intensely salty or tart. * **The Middle Stage:** Here, the sugar browning and caramel notes develop as the flow rate increases. * **The Tail End:** The final cups contain mostly "brown water"—highly dilute, slightly bitter, and watery. Tasting these individually reveals exactly where the flavors you enjoy (or hate) enter the cup. If your full shot is too sour, the Salami Shot proves that you likely need to let the later, more balanced stages of extraction run longer. Exercise 2: The Overpull Bypass If you find a recipe—say 18g in to 36g out—tastes too sour, don't just dump it. Keep pulling the shot for an extra 10 grams into two separate 5g "extension" cups. Taste your base 36g shot. If it’s lacking, add the first 5g extension and restir. This allows you to find your ideal yield without pulling multiple full shots. It’s a practical way to diagnose if your equipment or water temperature needs more contact time to balance the acidity. Exercise 3: The Pseudollongé Technique Sometimes, pushing more water through the coffee puck isn't the answer. As a puck breaks down, it offers less resistance, and the water flowing through it can extract harsh, astringent compounds. Instead of a long 1:5 ratio shot, try pulling a tight 1:2 shot and adding hot water directly to the cup. This "bypass" method, inspired by how whiskey drinkers use drops of water to open up aromas, can preserve delicate fruit notes while smoothing out a bitter finish. Decoding the Results By the end of these exercises, you will understand that extraction isn't a linear progression of "goodness." High extraction isn't always the goal. Often, a lower extraction yield with the right dilution provides a cleaner, more vibrant profile. Use these methods to build a personal lexicon of flavor, ensuring every shot you pull is a deliberate choice rather than a roll of the dice.

Navigating the Complexity of Espresso Espresso is often viewed as the final frontier for the home barista. It is intimidating, technical, and shrouded in conflicting advice from various online forums. However, making world-class espresso at home doesn't require a degree in fluid dynamics or a machine with a tablet interface. It requires an understanding of how specific variables influence the liquid in your cup. This guide will walk you through the essential mechanics of extraction, providing a pragmatic framework to transform your daily workflow from a guessing game into a precise craft. Tools and Materials Needed To achieve consistency, you need tools that offer feedback. At a minimum, ensure you have: * **Espresso Machine**: Any machine capable of sustaining pressure. * **Burr Grinder**: A high-quality grinder with fine adjustment capabilities. * **Precision Scale**: Accurate to 0.1g for weighing dose and yield. * **Portafilter and Baskets**: Sized appropriately for your desired shot volume. * **Tamper**: To ensure an even, level puck surface. * **Fresh Coffee Beans**: Preferably whole bean to preserve volatile compounds. Step 1: Establishing the Perfect Dose While many focus on weight, the primary goal of Dose is achieving the correct volume for your basket. You must respect the headspace—the distance between the coffee puck and the shower screen. To find your ideal dose, fill your basket, tamp it down, and lock it into the machine without brewing. Remove it immediately. If you see an indent from the screen or screw, you have too much coffee. Direct contact between the screen and the puck causes channeling, which ruins extraction. Conversely, underfilling results in a thin, watery texture. Tools like the Breville Razor can help you find this depth. Once you establish the correct volume, weigh it on your scale and keep that number consistent for that specific bean and roast level. Step 2: Calibrating Grind Size for Clarity Grind Size is your primary tool for managing resistance. Finer particles create more surface area but increase the risk of the water finding "channels" or paths of least resistance, leading to bitter, astringent flavors. If your espresso tastes muddied or lacks clarity, try grinding coarser. It is a mistake to believe that "grinding finer" is a universal fix. If a shot is sour, you may need a finer grind to increase extraction, but if you go too far, you’ll experience channeling that causes a hollow, acrid finish. Look for a balance where the water flows steadily, hitting your target yield without the appearance of "tiger striping" caused by excessive micro-fines. Step 3: Manipulating the Brewing Ratio Ratio is the most objective variable at your disposal. If your shot is balanced but too thin, decrease the ratio (e.g., 1:1.5 instead of 1:2). If it is thick but overwhelmingly sour, increase the ratio to 1:2.5 or higher. Coffee extracts in a predictable sequence: sour acids come first, followed by sweetness, and finally, bitter compounds and astringency. By simply letting more water pass through the puck, you pull more material out, which shifts the flavor profile away from sourness. If you want to test this without wasting beans, catch the tail end of your shot in a separate cup and add it back in increments to see how it changes the balance. Tips and Troubleshooting * **Ignore the Clock**: While the 30-second rule is a common benchmark, Contact Time is often a red herring. Focus on taste first; a 45-second shot can taste incredible if the grind and ratio are dialed in. * **Roast Level Matters**: Lighter roasts are less soluble and require higher temperatures and finer grinds. Darker roasts are fragile; use lower temperatures (around 85°C) to prevent burning the oils. * **Pressure Dynamics**: Don't obsess over maintaining 9 bars. As the puck erodes, resistance naturally drops. Forcing high pressure through an eroding puck late in the shot often creates more channels. Conclusion By treating Dose, Grind Size, and Ratio as your primary levers, you can navigate any bean or machine with confidence. The reward is a shot tailored to your specific palate—thick, syrupy, and perfectly balanced. Stop following rigid recipes and start responding to the flavors in your cup.

The espresso industry frequently finds itself caught between the nostalgia of 1960s mechanical engineering and the sterile allure of modern smart-home connectivity. Rarely does a product arrive that disrupts the core physics of brewing while maintaining a pedigree of high-end manufacturing. Enter the Unica Pro, a Swiss-made espresso machine developed by engineers from the biotech industry. This isn't just another shiny box with a pump; it represents a fundamental shift in how we manage thermal energy and water flow. By moving away from the traditional dual-boiler architecture that has dominated the high-end market for decades, the Unica Pro promises a level of precision and sustainability that makes its competitors look like relics of a more wasteful era. Dynamic Thermal Management and Energy Efficiency Traditional espresso machines rely on thermal mass—large boilers filled with water that take 20 to 30 minutes to reach a stable temperature. While this provides stability, it’s a nightmare for flexibility and energy consumption. The Unica Pro utilizes an 1,800-watt heating pad coupled with a heated brew group containing four distinct heating cells. This system allows for near-instantaneous temperature adjustments. In testing, the machine dropped from 91°C to 80°C with just a few quick flushes. This dynamic responsiveness is critical for enthusiasts who jump between light-roast espresso and lower-temperature milk drinks. Beyond performance, the environmental impact is staggering. Traditional dual-boiler machines are energy vampires, often consuming over 1,500 kWh per year because they must keep liters of water at near-boiling temperatures even when idle. The Unica Pro’s design, focusing on low thermal mass and a tiny half-liter steam boiler, brings that consumption down to approximately 70 kWh. In markets like Switzerland or California where electricity costs are skyrocketing, the machine practically pays for itself over a few years in energy savings alone. We are seeing the death of the large boiler, replaced by localized, on-demand heating that doesn't compromise on the three bars of steam pressure required for commercial-grade milk texturing. The Engineering Marvel of Flow Displacement Most high-end machines attempt to manage shot consistency through flow meters or complex algorithms that guess how much water has passed through the puck. The Unica Pro takes a more surgical approach. It features a massive 13 kg flow displacement pump driven by a stepper motor and a ball screw. This hardware allows the machine to move water with a granularity of 0.1 milliliters. This isn't just a marketing stat; it translates to incredible volumetric accuracy. When you program a 50 ml shot, the machine delivers exactly that, regardless of how the coffee puck resists the water. This "flow-first" philosophy is a significant departure from the pressure-profiling trend popularized by machines like the Decent DE1. While the Unica Pro can handle pressure profiling with nine distinct phases, its true strength lies in flow profiling. By dictating the flow rate—for instance, a static 1.6 ml/s—the machine allows the coffee puck to dictate the pressure. This avoids the common pitfall of pressure profiling where high-pressure water can dislodge particulates and cause astringency if the puck begins to degrade. The result is a more forgiving, consistently delicious extraction that highlights the inherent qualities of the bean rather than the brute force of the pump. User Experience and Firmware Versatility One of the most impressive aspects of the Unica Pro is its willingness to evolve. The interface offers both basic and extended menus, catering to both the "set-and-forget" user and the data-obsessed tinkerer. In a recent collaboration, I requested the ability to perform a "cool bloom"—brewing at 60°C during the pre-infusion phase before ramping up to 96°C for the extraction. Most manufacturers would take years to implement such a niche feature; the Unica Pro team delivered a firmware update in three days. This level of software agility is paired with high-end hardware like a stainless steel water tank and a high-accuracy hot water spout that can be programmed for specific tea temperatures. However, the experience isn't without its quirks. The current firmware still imposes some arbitrary limits, such as a 60-second shot timer and a 100 ml extraction limit on certain profiles. While these are minor software hurdles, they feel out of place on a machine that is mechanically capable of so much more. The "leaning" aesthetic of the chassis may also be polarizing, though it serves to house the massive internal pump and facilitates a surprisingly functional hands-free steaming experience. Final Verdict: The New Standard for the Endgame At a price point of €7,500, the Unica Pro is clearly not aimed at the casual consumer. It is a statement piece intended for those who want the absolute peak of coffee technology. It bridges the gap between the mechanical soul of a lever machine and the digital precision of a laboratory instrument. While machines like the La Marzocco GS3 or the Sanremo YOU offer prestige and proven performance, they lack the radical sustainability and the unique flow-displacement engineering found here. The Unica Pro is a harbinger of the future. It proves that we no longer need massive, inefficient boilers to achieve world-class espresso. As this technology matures and production scales beyond small Swiss batches, expect these innovations to trickle down to more affordable equipment. For now, if you have the budget and the desire for unparalleled control, the Unica Pro stands alone as the most innovative espresso machine currently on the market.

Preserving the Intangible: The Science of Volatiles Most coffee enthusiasts treat the bloom as a mere degassing phase, watching CO2 escape while the air fills with fragrance. However, that delightful aroma is actually the smell of flavor leaving your cup. Lance Hedrick highlights that during a traditional hot bloom, a significant portion of Volatile Organic Compounds (VOCs)—the chemicals responsible for fruity, floral, and candy-like notes—evaporate into the atmosphere before the first sip. This guide introduces the **Samo Bloom**, a technique designed to trap those delicate compounds in the liquid rather than losing them to the air. Essential Gear for Temperature Precision To execute this method, you need tools that allow for rapid temperature shifts or dual-temperature management. * **High-Quality Burr Grinder:** Consistency remains king; a fine-to-medium grind is standard. * **Variable Temperature Kettle:** Ideally two kettles, or one that heats quickly. * **Digital Scale:** Precision to 0.1g for the 1:15 or 1:17 ratio. * **Filtered Water:** Consistent chemistry ensures the VOCs translate accurately. Step-by-Step Execution of the Samo Bloom 1. **Prepare the Grounds:** Dose 15g of coffee into your brewer. 2. **The Cool Bloom:** Pour 45g (3x the weight) of water heated to **50°C - 60°C**. This lower temperature extracts the highly soluble, desirable volatiles without triggering rapid evaporation. 3. **The Wait and Reheat:** Let the coffee bloom for roughly two minutes. Use this time to crank your kettle up to **95°C - 96°C**. 4. **The Final Pour:** Once the kettle reaches the target high temperature, pour the remaining water (up to your total target, e.g., 250g) in a steady, concentric motion. This provides the energy needed to extract the remaining sugars and acids. Optimization and Troubleshooting If the final cup tastes too thin, consider grinding finer. The Samo Bloom can result in a slightly lower extraction yield compared to boiling-water blooms. However, this lower yield often leads to a cleaner finish with less bitterness. If the two-minute wait feels too long on a 110v kettle, you can compromise with an **80°C** bloom; it still preserves more aromatics than a standard 99°C pour while minimizing the reheating delay. The Result: A More Dynamic Cup By decoupling the aromatic extraction from the heavy-duty structural extraction, you achieve a more process-forward profile. Expect heightened acidity and a more pronounced aromatic presence that lingers on the palate. This method effectively replicates the benefits of "compound chilling" without the need for frozen metal balls or extra clutter in your workflow.

The Physics of the Puck: Why You Can’t Tamp Too Hard A common sight in specialty cafes is the barista leaning their entire body weight into a tamper to save a fast-running shot. However, Dr. Samo Smrke explains that human strength is no match for the hydraulic forces of an espresso machine. When you engage a standard pump, it exerts roughly nine bars of pressure—equivalent to a staggering 250 kg of force—onto the coffee bed. Most manual tamping falls between 15 and 25 kg. Once you reach full physical compression of the grounds, additional effort is wasted. The coffee particles are not perfectly rigid, but they hit a point of maximum density long before the machine takes over. If you notice a change in shot time when pressing harder, it is likely due to an unintentional change in your tamping angle, creating uneven density and channeling, rather than the pressure itself. Rethinking Freshness and the Gas Problem The "roasted yesterday" mantra is one of the most persistent myths in the industry. While stale coffee is certainly a problem, ultra-fresh coffee brings its own set of chemical hurdles. Freshly roasted beans are packed with carbon dioxide, which creates turbulent blooming in pour-overs and excessive crema in espresso, physically blocking water from effectively reaching the coffee solubles. More importantly, Dr. Samo Smrke identifies a specific volatile aroma compound called metan tile. This compound, also added to natural gas to give it a detectable scent, is highly concentrated immediately after roasting. It produces a harsh, "gassy" flavor that masks delicate notes. Because metan tile is oxygen-sensitive and degrades quickly, allowing coffee to rest for several days—or even weeks for light roasts—results in a more balanced and palatable cup. Boiling Point: Why You Aren't Burning Your Beans Many enthusiasts fear that using water straight off the boil will "burn" the coffee, leading to bitter, ashy flavors. In reality, you cannot burn coffee with water at 100 degrees Celsius. Burning requires temperatures closer to 180 or 200 degrees Celsius to trigger the chemical changes associated with smoky notes. What people perceive as a "burnt" taste is actually the efficient extraction of bitter compounds that are harder to dissolve at lower temperatures. High heat also increases the volatility of delicate aroma compounds, meaning they evaporate into the air before you can taste them. While 92 to 96 degrees might be a sweet spot for many beans, using boiling water is a tool for increasing extraction, not a recipe for scorching the grounds. The Acidity Paradox in High Extraction There is a common misconception that pushing for a high extraction yield (EY) will mute a coffee’s acidity. Chemically, this is impossible. Acids are among the most soluble compounds in coffee and are extracted early. As you continue to run water through the puck, the concentration of acids in your cup actually continues to rise. However, the concentration of bitter compounds increases at a much faster rate during the later stages of brewing. On the palate, these bitter notes dominate and overwhelm the acidity, leading to the perception that the vibrance has vanished. In reality, the acid is still there; it’s just buried under the weight of more stubborn, bitter material. The Myth of the Perfect 9-Bar Shot For decades, nine bars has been the industry standard for espresso. Yet, the relationship between pressure and flow is not linear because the coffee puck is compressible. As you increase pressure from six bars toward nine, you are simultaneously squishing the particles closer together, which increases resistance. In many cases, the extraction at six bars is indistinguishable from nine bars because the added pressure simply compacts the bed further rather than forcing more flavor out. Once you exceed 11 or 12 bars, the puck can undergo a secondary compression that causes the permeability to collapse, often leading to massive channeling and erratic shots. Instead of obsessing over a specific pressure, focus on the fundamentals: grind size, brew ratio, and consistent puck preparation.

The Shift in Extraction Theory For decades, coffee professionals operated under the assumption that mineral content primarily dictated the efficiency of extraction during the brewing process. However, recent insights from Dr. Samo Smrke suggest a radical alternative: minerals added after brewing yield identical flavor profiles to those present during the initial extraction. This shift suggests that cations like calcium and magnesium may not influence the chemical extraction of flavor compounds as significantly as previously believed, but rather serve as flavor modulators for the final beverage. The Role of Alkalinity Alkalinity acts as a buffer for coffee's natural acidity. In a controlled experiment using Lotus Coffee Water drops, varying levels of alkalinity—10, 30, 50, and 70 parts per million (PPM)—revealed distinct shifts in perception. At 10 PPM, the coffee remained tart and citric but lacked balance. Increasing to 30 PPM created a sweeter, more well-rounded profile. Beyond 50 PPM, the acidity began to flatten, introducing chocolatey notes but also undesirable "chalky" or "cardboard" textures. Practical Customization with Lotus Drops Lance Hedrick and Scott Rao demonstrate that brewing with distilled water and adding minerals post-brew offers a powerful troubleshooting tool. Since most roasters dial in their beans using specific local water, a consumer's home water chemistry might clash with the intended roast profile. By using concentrated drops, users can adjust hardness and alkalinity in real-time to match the roaster’s original intent or suit personal preference without wasting entire batches of coffee. The Hardness Constant While alkalinity drives the balance of acidity, general hardness—comprising calcium and magnesium—contributes to mouthfeel, creaminess, and complexity. Maintaining a constant hardness of 60 PPM while adjusting alkalinity allows for a systematic isolation of flavor variables. This level of control is essential because roasters often fail to provide detailed water chemistry data, leaving the consumer to bridge the gap between a sour or flat cup and the ideal extraction.

The Thermal Extraction Fallacy For years, the specialty coffee community operated under a rigid monolith: higher water temperatures yield higher extraction. Baristas routinely push water to the boiling point for light roasts, fearing that anything less would result in under-extracted, sour, or imbalanced cups. However, recent empirical testing suggests this relationship is far less linear than once thought. When controlled for other variables, the thermal energy of the water appears to have a diminishing impact on the actual Total Dissolved Solids (TDS) once a baseline threshold is met. Data Over Dogma In a rigorous comparison using a light-roasted, washed coffee from Manhattan Coffee Roasters, brewing at 100°C, 95°C, 90°C, and 85°C revealed a shocking statistical reality. The extraction yields across all four samples remained within four-hundredths of a percentage point of each other. This suggests that while temperature might alter the speed of extraction, it does not necessarily dictate the final volume of soluble material removed from the grounds in a standard pour-over. The acids that define a coffee's character are highly soluble and extract easily even at lower temperatures, provided the grind size and ratio are optimized. Sensory Nuance and Bitterness While the TDS remains stable, the sensory profile shifts. Collaborations with PhD chemist Samo Smrke indicate that higher temperatures often introduce perceived bitterness rather than increased sweetness or complexity. In blind tastings, extreme heat (100°C) often resulted in more vibrant but notably more bitter cups, whereas temperatures around 95°C frequently hit a "sweet spot" for balance. Interestingly, as temperatures drop toward 85°C, the aroma can become muted, even if the chemical extraction level is identical to a boiling-water brew. Practical Implications for the Home Barista The takeaway for the discerning consumer is clear: abandon the rigid temperature-to-roast formulas. If a light roast tastes astringent or overly bitter, lowering the temperature by 5-10 degrees might solve the issue without sacrificing extraction depth. Rather than following a prescriptive guide, brewers should conduct side-by-side tests at varying temperatures to find where their specific palate finds the best balance of vibrancy and clarity. Technology and technique should serve the user's enjoyment, not a rigid set of outdated rules.