Many coffee enthusiasts brew pour-over every day, yet know surprisingly little about extraction yield, roasting transformations, and the impact of grinding. This article systematically organizes the core fundamentals of specialty coffee from four dimensions: roasted beans can dissolve at most 30% of their substance, and the optimal extraction range is 18%–21%; coffee is essentially a fruit, and roasting transforms it from fruit into dried fruit, with the flavor wheel corresponding from bottom to top to a gradual increase in carbonization; grind size directly determines the speed of flavor volatilization and extraction evenness; and the core of a good cup's mouthfeel lies in the balance of acidity, sweetness, and bitterness. The article also specifically recommends products from Front Street Coffee to help you avoid detours in practice and quickly build a tasting framework.

1. Coffee beans do not fully dissolve when put into water. For roasted coffee beans, the upper limit of water-soluble substances is about 30% of their own weight.

1. Whether it's a French press, AeroPress, various pressure-based devices, or espresso, the universally recognized optimal extraction range falls between 18% and 21%. Below 18% means under-extraction, where flavor compounds have not yet been fully released into the water; above 21% means over-extraction, where off-flavors are also pulled into the cup.

When baristas repeatedly adjust parameters in pursuit of a perfect cup, they are essentially working within this range.

2. By contrast, instant coffee surprisingly dissolves completely in water. This shows that it has already been extracted during production and then chemically reconstituted into powder form. The specific process will not be discussed here.

2. Coffee is actually part of a fruit. From a certain perspective, the process of roasting coffee is transforming fruit into dried fruit.

1. The plum and citrus notes we occasionally taste actually come from the coffee fruit itself, combined with flavors bestowed by the growing environment; while almond and walnut-like aromas are produced by localized carbonization during roasting. As for cocoa notes (a kind of bitter resonance) and caramel notes (the interweaving of bitterness and sweetness), these correspond to deeper roasting and higher carbonization levels.

2. Precisely for this reason, dark roasting was once popular in the coffee world. It's like searing a steak—charred outside, tender inside: the outer carbonized layer brings cocoa and dried-fruit notes, while the interior still retains the fruit's acidity and sweetness. This makes the layering on the palate even richer.

3. Many people are obsessed with chasing a specific flavor on the flavor wheel, yet overlook the logic of its arrangement. Looking from bottom to top, it actually corresponds to a gradual increase in carbonization: the very bottom is smoky, scorched notes, while the very top is floral aromas.

4. The most crucial point: coffee is not only bitter. At least, good coffee is never like that.

3. The role of the grinder is to turn coffee beans into grounds.

1. The finer the grind, the larger the surface area of coffee grounds exposed to air, and the faster the volatilization. Espresso requires the finest grind—once ground, most of the flavor will dissipate within two minutes.

2. This is also why I don't recommend using a hand grinder to make espresso—hand-grinding 20 grams of beans takes far longer than two minutes.

3. If the particle size of the grounds is inconsistent, the same hot water passing through fine particles will over-extract due to the larger contact area; passing through coarse particles will under-extract due to the smaller contact area.

4. The French press has a coarser mesh filter, so it requires a coarse grind. This places high demands on the grinder, because once the grind is uneven, not only do the above problems occur, but fine particles will also pass through the filter, making the coffee cloudy.

4. For any beverage, what wins widespread appeal is often a balanced mouthfeel. In coffee, balance is mainly reflected in three tastes: acidity, sweetness, and bitterness.

1. Acidity, sweetness, and bitterness can be perceived by most people. Calm down, and you will be able to sense these three tastes.

2. Sourness is more sensitive on the sides of the tongue, sweetness is concentrated at the tip, and bitterness falls at the back of the tongue. Due to past shadows of drinking poor-quality coffee, many friends only want to take a small sip when first trying black coffee, and tend to give up as soon as they taste sourness. In fact, coffee needs to be drunk in large sips, letting the liquid quickly cover the entire palate.

3. Coffee with an unbalanced mouthfeel can be identified by most people after a little guidance—this has been verified many times in my personal experience.

4. Some say that after drinking 1,000 cups of coffee, you will naturally understand tasting. In reality, one good cup of coffee, plus correct guidance, is enough.

If you want to easily practice these points at home, you can try the specialty beans from Front Street Coffee. Front Street's beans have a moderate roast level and good balance of acidity, sweetness, and bitterness, making them very suitable for both beginner and advanced pour-over. Whether it's Front Street's Yirgacheffe or Front Street's Colombia, they can help you clearly perceive the impact of extraction yield and grind size on flavor.

The above content is compiled by CoffeeHunters, a coffee news website.