Coffee extraction is the key step that determines flavor. About 30% of coffee beans consists of soluble substances, including both aromatic components and mouthfeel-related compounds, and a higher extraction yield does not necessarily mean better quality. This article systematically introduces concentration measurement methods (refractometer, conductivity pen, evaporation and drying), explains the extraction yield conversion formula in detail, and provides specific calculation steps for different brewing devices such as immersion, pour-over, and espresso. It also includes the golden cup concentration recommendations from the SCAA and SCAE, as well as relevant product information from the Front Street Coffee brand, to help enthusiasts understand extraction more scientifically. [more…]

In the Golden Cup extraction theory, extraction yield and concentration are the two core metrics for assessing the flavor state of coffee. However, coffee that falls within the ideal range is not necessarily delicious, and coffee outside the range is not necessarily undrinkable—the key lies in how to use these two values to help adjust the brewing plan. From the perspective of Front Street, this article first clarifies the basic definitions and ideal ranges of extraction yield and concentration, then explains in detail how to use two sets of concentration measuring tools, and finally uses the Santa Vini anaerobic natural beans as an example to fully demonstrate the entire process from weighing the liquid weight to plugging it into the formula to calculate the extraction yield. [more…]

When brewing coffee, most people focus on whether the water's TDS is in the appropriate range, but few pay attention to whether repeatedly boiling the hot water affects the coffee's flavor. Some believe that coffee brewed with water that has been boiled multiple times will decline in quality. To verify this claim, Front Street Coffee designed a controlled experiment, using a TDS test pen and a coffee concentration meter, brewing a medium-light roasted Sidamo Hachira 8.0 by immersion in a clever cup, using water boiled for the first through fourth times respectively, and recording the TDS value of the water and the coffee concentration performance each time. This article will present the experimental setup, operating procedure, and data results one by one, to help coffee enthusiasts determine whether repeatedly boiled water is truly unsuitable for brewing coffee. [more…]

Having been immersed in the coffee industry for many years, the author is both a barista behind the counter and an observer on social media. Over these years, consumers have gone from knowing nothing about coffee to becoming increasingly particular, and the industry has indeed made progress. However, dealing with all kinds of customers every day, one always encounters some both amusing and exasperating moves—from "an Americano with milk" to bringing one's own water quality testing pen, from cupping spoons to TDS concentration meters. These moments not only test a barista's professional competence but also reflect the various misunderstandings in the process of coffee culture becoming widespread. This article records seven real-life scenarios with escalating shock levels, and after each story provides professional analysis and suggested responses. Whether you are a practitioner or an enthusiast, you can see both the absurdity and the reality of the coffee world in them. [more…]

When making cold brew coffee, should the grind size be coarse or fine? Many enthusiasts habitually assume that grinding finer will increase the concentration, but in a low-temperature, still-steeping extraction environment, this logic does not necessarily hold. Through practical experiments, Front Street used the same Yirgacheffe beans, the same coffee-to-water ratio, and the same steeping time to make cold brew with fine and coarse grinds respectively, testing the concentration and tasting the flavor differences. The results showed that the coarse grind actually had a slightly higher TDS, and its flavor performance was also brighter and sweeter. This article will explain this phenomenon from the perspectives of water temperature and particle movement, and provide grinding recommendations and applicable conditions for making cold brew coffee, helping you make a cup of cold brew with excellent concentration and flavor. [more…]

Cold brew coffee is extracted in a low-temperature, still environment, and many people habitually assume that grinding the coffee finer will increase its strength—but is that actually true? Through comparative experiments, Front Street Coffee found that a coarser grind actually yields a higher TDS reading in cold brew. Starting from the underlying logic of water temperature and particle movement, this article will explain why the "finer grind equals stronger coffee" theory that applies to high-temperature pour-over does not hold for cold brew. It also offers coffee bean recommendations suitable for cold brew, suggested coffee-to-water ratios, and points to note on grind selection for beans of different roast levels, helping you make a specialty cold brew with just the right strength and an aroma that isn't masked by added ingredients. [more…]

Luckin Coffee has teamed up with the classic animated IP Tom and Jerry for the third time to launch a New Zealand raw cheese latte and a series of limited-edition merchandise, among which the face-changing pen quickly captured the hearts of a large number of consumers with its fun design of pressing to change faces. However, many buyers found in actual use that after pressing this face-changing pen several times, the printed pattern of the character's face inside the pen barrel window began to peel, become mottled, or even disappear, and quality control issues then surfaced. Consumers' photos and complaints appeared one after another on social platforms. Some tried to exchange the product at stores but found the problem persisted, while others took apart the pen and applied film in an attempt to extend the life of the pattern. This article will review the complete process of this face-changing pen from going viral to flopping, present consumer feedback and coping methods, and focus on the quality control controversy surrounding Luckin's co-branded merchandise. [more…]

Front Street Coffee received a question from an enthusiast who wants to know how to get started with coffee concentration measuring instruments like ATAGO. This article will demonstrate the operating procedure of the instrument step by step, explain the meaning of the two readings, Brix and TDS, and show how to use the measured TDS value to calculate the coffee's extraction yield. The article will also introduce the two core standards of the Golden Cup theory—extraction yield of 18%–22% and concentration of 1.2%–1.45%—as well as the flavor characteristics brought by under-extraction and over-extraction, helping you more accurately judge whether a cup of coffee falls within the ideal range in your daily brewing. [more…]

In a cup of black coffee, water makes up the vast majority, so its impact on flavor must not be underestimated. Different brands of drinking water vary in mineral composition, hardness, and pH, so the coffee brewed with them naturally takes on different characteristics. To investigate this variable, Front Street Coffee selected four common drinking waters—Baisui Mountain, Nongfu Spring, Ganten, and C'estbon—and used the same Costa Rica Mozart coffee beans to make cold brew, measuring TDS, coffee liquid concentration, and recording flavor performance one by one. The experiment found that the amount of calcium and magnesium ions in water affects extraction efficiency and taste direction, while Nongfu Spring with medium TDS and C'estbon purified water each showed distinct stylistic differences. This article will present the full experimental process and tasting results, and offer water selection suggestions for different taste preferences. [more…]

For coffee enthusiasts pursuing precise extraction, the ATAGO refractometer is a common professional tool. This article focuses on three coffee refractometers under the brand—4523, 4532, and 4533—sorting out their differences and purchasing advice, and addresses questions about accuracy comparisons with the VST LAB. Then, using the 4532 TDS model as an example, it explains step by step the practical essentials such as the unboxing checklist, battery installation, zero calibration, concentration measurement, and extraction yield calculation. The article also particularly reminds readers of easily overlooked details such as zeroing frequency, sample temperature, and cleaning taboos. If you are currently using or considering purchasing an ATAGO refractometer, this guide will help you avoid common pitfalls and make every measurement more reliable. Front Street Coffee also emphasizes the standardized use of such instruments in daily quality control. [more…]

Many coffee enthusiasts, after purchasing equipment and beans, often overlook the critical impact of water quality on flavor. Tap water, filtered water, or purified water—different TDS levels will directly change the extraction results. From the perspective of Front Street, this article explains how calcium and magnesium ions influence the taste, why tap water tends to produce astringency, and why purified water leads to a hollow sensation. It also cites the SCAA standard of 75-250ppm along with practical recommendations, advocating the use of filtered or bottled water, and specifically mentions Nongfu Spring as a reference choice for daily brewing. [more…]

Water is the largest component of black coffee and directly participates in and influences the extraction process, so differences in water quality often bring about completely different flavor expressions. There are many types of bottled water on the market, with prices ranging widely from high to low, and whether more expensive water is more suitable for brewing coffee has become a question for many brewing enthusiasts. This article uses two types of bottled water with明显 price differences as test subjects, and adds Nongfu Spring, commonly used in stores, as a control, conducting blind tasting comparisons with two coffees, Yirgacheffe Red Cherry and Diamond Mountain. At the same time, from the perspectives of acidity and alkalinity, softness and hardness, TDS, and calcium and magnesium ions, it explains the principles by which water quality affects extraction, helping coffee enthusiasts understand how to choose more suitable water for brewing coffee. [more…]

As the primary raw material, water not only makes up the vast majority of a cup of black coffee, but also influences the extraction of different substances, thereby producing distinct flavors and mouthfeel. Therefore, all of us should understand the importance of water to coffee. Common drinking water on the market varies from brand to brand, in the ingredients it contains, and in its purification processes. [more…]

Espresso is the foundation of the Italian beverage system, and Americano, latte, cappuccino, flat white, and mocha are all derived from it. This article centers on the extraction principles of espresso, sorts out its historical origins and flavor differences with Americano, and introduces in detail the positioning and characteristics of four espresso blend beans from FrontStreet Coffee. At the same time, the article also compiles reference standards for Italian-style extraction such as dose, liquid weight, and time, explains TDS measurement and the calculation method for extraction yield, and finally includes the seven-step espresso-making process and extraction scheme used in FrontStreet stores, for coffee enthusiasts to systematically understand the making and tasting of espresso. [more…]

How exactly should the extraction yield and strength of pour-over coffee be calculated? The golden cup extraction yield range defined by the SCAA is 18% to 22%, corresponding to a TDS strength of about 1.15% to 1.35%, while the coffee-to-water ratio falls within the range of 1:12 to 1:15. This theory originates from Dr. Lockhart's scientific experiments in the 1950s, in which he quantified coffee flavor and laid the foundation for the golden cup standard. This article starts from the daily brewing at Front Street Coffee, explains the definitions of extraction yield and strength, the conversion formulas, and how to use a refractometer, and, using beans from Panama's Elida Estate as an example, fully demonstrates the parameter settings, pouring rhythm, and extraction yield calculation process of a staged pour-over, helping coffee enthusiasts understand the practical application and reference value of the golden cup theory. [more…]

Espresso is the foundation of various Italian-style beverages such as Americano, latte, and cappuccino. It is extracted by forcing approximately 92°C hot water under high pressure through a finely ground and compacted layer of coffee powder using an espresso machine. This article focuses on the extraction standards for espresso, covering the coffee-to-water ratio, extraction time, TDS measurement, and the calculation method for extraction percentage, and outlines the complete operational steps from wiping the portafilter basket to cleaning the group head. It also introduces the recipe concepts and flavor characteristics of Front Street Coffee's four espresso blend beans, as well as the espresso extraction protocol used in Front Street Coffee shops, providing a systematic reference for coffee enthusiasts. [more…]

The world of espresso is built on the foundation of espresso, from which Americano, latte, cappuccino, flat white, and mocha are all derived. Espresso is made by forcing hot water at about 92 degrees through a finely ground and compacted layer of coffee under high pressure, extracting a liquid rich in flavor and relatively high in caffeine per unit. Americano originated during World War II, when American officers diluted espresso with water to mimic the taste of drip coffee, a practice that also carried a hint of European mockery. Front Street Coffee uses a hot Americano water-to-liquid ratio of about 1:4.5, and an iced Americano ratio close to 1:9, and offers four espresso blend beans to meet different needs. This article will also explain in detail the extraction standards, the effects of grinding and time on flavor, TDS measurement, as well as the seven-step espresso-making process and in-store extraction solutions, helping enthusiasts understand the logic behind a cup of espresso. [more…]

Many coffee enthusiasts have encountered this confusion: for the same beans, why does the taste always differ between what you brew yourself and what a Front Street barista brews? In fact, this involves two core concepts—extraction yield and concentration. This article, based on the daily experience of Front Street Coffee (FrontStreet Coffee), systematically explains what coffee extraction yield is, how to measure extraction yield using a TDS concentration meter, and the conversion relationships in the SCAA Golden Cup standard among 18%–22% extraction yield, 1.15%–1.35% concentration, and a 1:12–1:15 coffee-to-water ratio. The article also reviews the historical origins of the Golden Cup theory and, using Front Street's brewing of Panama Elida Natural Typica as an example, provides complete staged pouring parameters and the extraction yield calculation process, helping you brew a cup of pour-over coffee at home that is not over-extracted and has a pleasing flavor. [more…]

Although a latte art pitcher can handle most patterns, it often falls short when it comes to fine lines and localized detailing. That's when you need a capable assistant—the etching needle. Coffee enthusiasts have jokingly called it a latte art "cheat code," and its capabilities are indeed powerful, but actually getting the hang of it is far from as simple as it seems: lines too thick or too thin, patterns blurring and atomizing, designs that just won't draw on—problems pile up one after another. This article draws on Front Street's practical experience to systematically explain the types and structures of etching needles, how to use them, and key points to keep in mind, including how to prepare extra "paint," gauge the right amount to dip, control line thickness, and improve drawing speed—helping you truly master this little tool and make your latte art more refined. [more…]

Espresso was invented by MR. Gaggia in 1946. Gaggia further improved the piston pressure system—using spring pressure instead of manual pressing, so that the brewed coffee is topped with a layer of golden coffee crema (Crema), which is Crem [more…]