When brewing pour-over coffee, water quality is one of the key variables that determines flavor expression. This article focuses on the two core indicators of water: hardness and pH, explaining the TDS range recommended by the SCAA as well as the water quality range that more easily yields good taste in actual brewing, and explaining the effects of calcium and magnesium ions on coffee acidity, sweetness, and aroma. The article will also analyze one by one whether tap water, filtered water, purified water, and mineral water are suitable for brewing coffee, reminding readers to pay attention to the TDS and mineral content on labels, and to avoid judging water quality based on price alone. Finally, it offers practical advice on water for daily brewing to help coffee enthusiasts reproduce coffee flavors more consistently. [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…]

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…]

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…]

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…]

To brew a delicious cup of coffee, you need not only good beans but also good water. In brewed coffee, water accounts for over 98% of the final cup. Therefore, choosing the right water for brewing is also crucial. So what kind of water is actually suitable for brewing coffee? First, Front Street Coffee will explain the requirements for water suitable for brewing coffee. One [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…]

When brewing a pour-over coffee, water accounts for up to 98.7%, making its importance no less than that of the coffee beans and grinder. In this article, Front Street Coffee analyzes how water quality affects flavor, the mechanism by which calcium and magnesium ions in water act, and the recommended TDS range. It also uses examples to explain how, when coffee develops off-flavors or negative mouthfeel, you can troubleshoot the problem by switching water sources such as Nongfu Spring, helping enthusiasts on a limited budget spend their money where it matters most. [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…]

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…]

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…]

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…]

Coffee extraction, simply put, is the process of using water to dissolve the flavorful essence from coffee beans. It seems like something that can be summed up in a single sentence, but behind it lies a whole series of precise variables: extraction yield, total dissolved solids, water quality, grind size, temperature, time, and more. Roasted coffee beans are about 30% soluble, and what we aim for is extracting 18-22% of that—the optimal range. We don't want under-extraction, which leads to sharp acidity and a thin, bland cup, nor over-extraction, which brings bitterness and off-flavors. This article will start from the basic definition of extraction and break down, one by one, the nine core factors that affect extraction, helping you build a systematic framework for understanding brewing so that every cup consistently delivers the ideal flavor. [more…]

Many coffee enthusiasts have heard of the Golden Cup extraction theory: ideal concentration 1.15%-1.35%, ideal extraction yield 18%-22%. But this standard actually comes from the SCAA, not the SCA; the European and American coffee associations each have their own positions on ideal concentration. After the SCAA and SCAE merged in 2017, the UC Davis Coffee Center made slight adjustments to the old brewing control chart, loosening the upper concentration limit and the brew ratio range. This article will start with the history of the Golden Cup theory, sort out the differences between the old and new control charts, explain why high concentration with low extraction can highlight acidity while low concentration with high extraction can bring out floral and chocolate notes, and, combined with product information from Front Street Coffee, help you understand how concentration and extraction yield should be judged together, rather than fixating on a single number. [more…]

When brewing a good cup of tea, water quality is often more critical than technique. As early as Lu Yu's "Classic of Tea," spring water was regarded as the finest choice, and modern science has revealed the reasoning behind this through TDS, hardness, and pH values. This article focuses on the brewing water for oolong teas such as Phoenix Dancong, outlines the industry reference values from the American Tea Association, and cites multiple studies to explain why soft water enhances the sweetness, freshness, and clarity of the tea liquor, while hard water brings about astringency and floating residue. For tea lovers who cherish the complex aroma of oolong tea, choosing the right water is the first step in unlocking the tea's charm. Front Street Coffee also recommends starting with low-mineralization soft water to appreciate the subtle variations in the tea's layers. [more…]

Over 98% of a cup of drip coffee is water, and water quality affects the final flavor second only to the coffee beans themselves. From the perspective of Front Street, this article systematically sorts out the pH range of brewing water, the roles of calcium and magnesium ions and bicarbonate, and verifies through comparative experiments the flavor differences when using purified water, mountain spring water, and mineral water to extract the same beans. It also answers whether tap water is suitable for brewing coffee and provides practical reference for choosing water in daily life, helping coffee lovers find a more stable brewing water solution. [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…]

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…]

Can coffee grounds be thrown straight into a pot like instant noodles? Front Street Coffee put this question to the test in a round of hands-on experiments. This article documents the full steps and parameters for pot-brewed coffee, starting with a medium-roast Brazil Red Bourbon bean and moving on to a light-roast Peru Washed Geisha, for three rounds of testing in total. The article compares how different coffee-to-water ratios, grind sizes, and boiling times affect flavor, and also presents changes in TDS values, taste descriptions, and methods of straining out the grounds. If you want to know whether coffee grounds can really be boiled and drunk, this hands-on record from Front Street Coffee will give you a straightforward answer. [more…]

In recent years, with the rise of the specialty coffee wave, more and more people choose to buy beans and take them home to brew a cup of coffee for themselves, enjoying a leisurely moment. But everything is hard at the beginning, and many beginners wonder, "The coffee I drank in your shop was so good, why can't I brew the same flavor when I go home?" Part of the reason [more…]