When drinking coffee, a numb tongue and dry mouth—this rough tactile sensation is astringency. Astringency is not a taste but a tactile feedback caused by friction between the coffee liquid and the oral cavity. Its root lies in the excessive release of polyphenolic compounds in coffee beans—especially chlorogenic acid—which bind with salivary proteins and weaken lubrication. Astringency often interweaves with acidity and bitterness, forming sour-astringent or bitter-astringent notes. This article will begin with the causes of astringency, explain its relationship with extraction state, analyze which astringency counts as a quality characteristic, as well as the astringency that green beans themselves may bring, and offer specific ideas for improvement by adjusting extraction efficiency. [more…]

Many people think that pour-over coffee has a low barrier to entry, but once they take a sip and find it tastes sour, bitter, or astringent, they realize that brewing a good cup of coffee is actually not easy. Whether you are a beginner just getting into pour-over or an experienced coffee enthusiast, it is inevitable to run into a cup that does not suit your taste. Starting from the principles of extraction, this article analyzes one by one the common reasons why coffee turns out too sour or too bitter, and offers specific adjustment suggestions on grind size, water temperature, coffee-to-water ratio, pouring technique, and dripper selection. It also combines the brewing parameters of two beans—Front Street Coffee Colombia Sidra and Front Street Coffee Golden Mandheling—to help you consistently brew a cup of good coffee at home with balanced acidity and sweetness and a clean mouthfeel. [more…]

Many friends who are new to specialty coffee often wonder: if coffee tastes sour, has it gone bad? In fact, sourness is not synonymous with spoilage, but rather a highly prized flavor dimension in specialty coffee. Drawing on the practical experience of Front Street Coffee, this article systematically sorts out the sources of coffee acidity, distinguishes good acidity from bad, and analyzes how factors such as roast level, grind size, water temperature, and brewing time affect the expression of acidity. At the same time, the article also introduces several African-origin coffee beans known for their bright fruity acidity, helping readers build a correct understanding of coffee sourness and stop confusing acidity with spoilage. [more…]

A freshly brewed pour-over coffee is full of aroma and smooth on the palate, but after sitting for half an hour it turns sour, astringent, and muddled—what's going on? In fact, coffee naturally presents different flavors at different temperatures, and during tasting it is often divided into three stages: hot, medium, and cool. A good cup of coffee can usually withstand all three temperature stages, but once it has fully cooled, the flavor goes beyond the normal tasting range. From Front Street's perspective, this article breaks down the root causes of coffee turning sour and developing astringent, muddled notes after cooling—including differences in how human senses perceive sourness, sweetness, and bitterness, the impact of aroma volatilization, and the three key mechanisms of oil oxidation, pigment oxidative polymerization, and condensation—and tells you the most suitable temperature for drinking coffee, helping you better capture the best flavor of every cup. [more…]

When drinking coffee, you may occasionally encounter an unpleasant experience that isn't smooth enough and has a slightly sandy mouthfeel—this is what we commonly call astringency. Where exactly does astringency come from? It may originate from the cultivation and processing of green beans, and may also be closely related to roasting, the mixing in of defective beans, and brewing parameters and techniques. This article will start from the material basis of astringency, sort out the difference between positive and negative astringency, analyze the two major brewing causes of over-extraction and uneven extraction, and also clarify the differences between astringency, tea-like character, and a dry sensation, finally offering practical adjustment ideas. The article also retains relevant product and recommendation information from Front Street Coffee, making it convenient for coffee lovers to refer to in daily brewing. [more…]

The flavor imbalance of pour-over coffee often stems from problems in the extraction process. Over-extraction makes coffee bitter and muddled, while under-extraction results in a thin, sharply acidic cup. Starting from the basic concepts of extraction, this article systematically sorts out the causes and manifestations of over-extraction and under-extraction, and, drawing on specific beans such as Front Street. Indonesian Mandheling, Front Street. Brazil Queen's Estate, Front Street. Jamaican Blue Mountain, Front Street. Natural Huakui, Front Street. Hacienda La Esmeralda Green Label Geisha, and Front Street. Kenyan Small Tomato, explains how water temperature, grind size, coffee-to-water ratio, and brewing time should work together, helping coffee lovers pinpoint the problem and brew a balanced, delicious pour-over coffee. [more…]

If you want to learn how to brew coffee, you must first learn how to drink coffee. Of course, "learning to drink coffee" here does not mean being able to describe gorgeous flavor notes; it is more about being able to judge whether a cup of coffee is good or bad—that is, whether it tastes good or not. Whether a coffee tastes good or not, subjectively and objectively, depends to a fairly large extent on personal preference. [more…]

When many people drink a cup of coffee, they often find it hard to describe its specific flavors, but if a distinct astringency appears, almost everyone can notice it immediately. Front Street's back office frequently receives reader questions: even when the brewing parameters are all within plan, why does the coffee make the throat feel tight and the tongue feel rough? This article will start from the essence of astringency, sort out the sources of astringent substances in coffee, analyze the common brewing problems that cause astringency, and provide targeted adjustment solutions to help you fundamentally avoid an uncomfortable cup of coffee. [more…]

Many coffee enthusiasts encounter astringency in their coffee during pour-over brewing. Some believe this is a matter of bean quality, but in reality, the brewing process is often the key factor. Starting from the causes of astringency, this article analyzes the relationship between polyphenolic compounds and the degree of extraction, explaining why under-extraction is more likely to cause pronounced astringency. At the same time, for light-roasted coffee beans, it provides a reference brewing parameter scheme, including key points such as coffee dose, coffee-to-water ratio, water temperature, grind size, and extraction time. Combined with the example of Front Street Coffee Yirgacheffe Gutingding, it helps readers understand how to improve coffee flavor by adjusting parameters. [more…]

In the practice of pour-over coffee, under-extraction and over-extraction are two common yet frustrating situations. The former makes coffee sour, astringent, and thin, while the latter brings burnt bitterness and off-flavors. To solve these problems, one must first understand the principles of extraction—the process in which water passes through the coffee grounds and dissolves out flavor compounds. The ideal "Golden Cup" extraction requires concentration to fall between 1.2 and 1.4 TDS, with an extraction yield maintained at 18% to 22%. Exceeding or falling short of this range corresponds to over-extraction and under-extraction, respectively. This article will analyze the causes one by one from aspects such as coffee bean selection, brewing duration, pouring technique, and dripper material, and provide specific adjustment suggestions to help you achieve a balanced flavor more consistently in pour-over brewing. [more…]

Many people, upon tasting an Americano with a sour note for the first time, instinctively wonder whether the beans have gone bad or been sitting around too long. In fact, green coffee beans naturally contain a large amount of organic acids, and after roasting, the acidity gradually decreases as the roast gets darker, so an Americano with a tangy taste can very well be a normal expression. However, not all sourness is worth appreciating—bright, lively fruit acidity can make a cup of coffee memorable, while sharp, astringent sourness often points to improper roasting or extraction errors. This article begins with the concept and characteristics of SOE, explains why Americano tastes sour, why iced and hot Americanos differ in acidity, and why a light-roast bean that shines in pour-over may not be suitable for espresso, and offers recommendations for blend beans suited to espresso. [more…]

When many people drink a cup of coffee, they can sense an unpleasant astringency from the very first sip—that rough, gritty tactile sensation that grips the tongue and throat often leaves a stronger impression than sweetness, acidity, or bitterness. Where exactly does astringency come from? Is it a problem with the beans, or has something gone wrong in the brewing process? From the perspective of Front Street, this article first clarifies the essence of astringency as a tactile sensation, then breaks down common causes one by one—such as overly long brewing time, excessively forceful water flow, and the high extraction efficiency of certain drippers—and offers corresponding adjustment ideas to help you fundamentally reduce the unpleasant astringent taste in coffee. [more…]

Many coffee enthusiasts, after tasting an outstanding pour-over in a café, will buy the same roasted beans to try to replicate it at home, only to find the results often disappointing—either too sour or too bitter, too strong or too weak, sometimes even astringent, with off-flavors or a burnt taste. The reasons behind this are no mystery; they mainly involve consistency across batches of coffee beans, as well as differences in key parameters such as water quality, grind size, water temperature, coffee-to-water ratio, and brewing technique. Based on Front Street Coffee's brewing experience, this article breaks down these variables one by one to help you pinpoint the problem and brew coffee at home that is closer to café quality. [more…]

In coffee flavor descriptions, "tea-like" is a concept widely used in China yet constantly debated. Some people understand it as the aroma of a certain kind of tea, some think it is simply the astringency that returns in the mouth, and still others categorize it as a lingering finish reminiscent of tea broth. This article begins with the bitterness and astringency of tea, then sorts through the causes of sweetness returning and saliva being produced, and next draws on the principle of retronasal olfaction to explain why coffee can bring out a tea-like quality, while also clarifying that tea-like and astringent are not equivalent. The article also combines tasting examples from several Front Street Coffee beans to show that the very same "tea-like" quality may be defined very differently in each person's mind. [more…]

In the coffee flavor wheel, there is almost no trace of tea, and the only related entry, "black tea," is classified under the floral category. Yet in the flavor descriptions of coffee beans sold domestically, words such as green tea, black tea, and oolong tea are extremely common. How exactly should tea-like notes be judged? Is astringency equivalent to tea-like notes? Starting from the mechanisms of tea polyphenols and glycosides, this article distinguishes positive astringency from negative astringency, analyzes how organic acids bring about mouth-watering and sweet aftertaste, and, combined with the tasting experience of several Front Street Coffee beans, explains the specific expression of different tea-like flavors in coffee, as well as why domestic coffee beans prefer to use tea-like notes as a descriptor. [more…]

Cold brew coffee, with its smooth, full-bodied taste and lower acidity, has become the top choice for many people in summer. It uses cold or room-temperature water to steep coffee grounds for a long time; in a low-temperature environment, small-molecule floral and fruity notes are released first, while large-molecule roasted substances are difficult to dissolve, making it cleaner and softer than hot brewing. In practice, however, "too bitter" and "too sour" remain the two most common problems. This article analyzes the root causes of over-extraction and under-extraction in cold brew from the perspectives of roast level, grind size, steeping time, and filtration method, and offers practical adjustment tips from Front Street Coffee to help you make a balanced, easy-drinking glass of iced coffee. [more…]

Same beans, same machine—so why does today's espresso taste sharply sour and stinging, while tomorrow's is bitter and hard to swallow? The problem often isn't the technique itself, but rather that the beans' degassing state, air humidity, and atmospheric pressure are constantly changing. Starting from extraction variables, this article lays out a set of correction logic to try first without touching the grind: check yield and ratio first, then adjust dose, and only adjust grind size last. Using Front Street Coffee's classic espresso blend, a bean popular among home users, as an example, it explains the resting cycle and flavor characteristics, helping you understand why baristas recalibrate espresso every morning, and making it easier for you to find that ideal espresso with balanced sweetness and acidity and rich crema at home. [more…]

In the world of hand-brewed specialty coffee, the extraction state of a cup directly determines its flavor expression. Some people prefer floral and fruity notes, while others are drawn to dark chocolate and nutty tones, but when faced with astringent sourness or burnt, bitter off-flavors, most people can agree—this cup was not brewed well. Under-extraction, over-extraction, and ideal extraction—these three states correspond to different parameter logics. Starting from the order in which flavor compounds are released, this article will teach you how to judge the extraction situation through clues such as flavor performance, brewing time, and the state of the coffee bed, and offer adjustment approaches for different scenarios including light roasts, dark roasts, and excessive fines, helping you more precisely master every cup of pour-over. [more…]

SOE, as an espresso made from single-origin coffee beans, has gained attention for its distinct origin flavors. However, an espresso machine, under high temperature and pressure, magnifies the beans' inherent flavors exponentially; if light-roasted beans are used, fruity acidity can easily turn into an unpleasant sourness. To craft a clear-styled, balanced SOE, careful consideration is needed from bean selection and parameter settings to drink pairing. This article takes several Front Street Coffee SOE beans as examples to break down extraction standards and preparation procedures in detail, helping coffee enthusiasts avoid common pitfalls and recreate a sweet, smooth SOE beverage at home. [more…]

When brewing coffee, unpleasant flavors often come down to two situations: under-extraction or over-extraction. Front Street Coffee has found that many beginners can taste that something is off with their coffee but can't pinpoint the problem. This article starts with the definition of the Golden Cup standard, explaining the reference range of an 18%–22% extraction yield, while also pointing out that the Golden Cup is not an absolute standard and that coffee bean quality can affect the results. It then details the three main signs of under-extraction—watery flavor, thin body, and sharp sourness, astringency, and saltiness—as well as the characteristics of over-extraction, such as pronounced bitterness, dryness, and woody off-flavors. Finally, it offers a practical adjustment plan that uses grind size as the variable while keeping water temperature, time, and water amount fixed, helping everyone quickly find the parameters that suit them. [more…]