For coffee to taste good, freshness is the first requirement, and mastering the grind size is the second priority, directly affecting the extraction effect and the strength of the flavor. In principle, the finer the coffee grounds and the longer the brewing time, the stronger the taste; conversely, the weaker it is. The longer the extraction time, the coarser the beans should be ground, to avoid over-extraction leading to bitterness; the shorter the extraction time, the finer the beans should be ground, to avoid under-extraction. Different brewing devices have different requirements for grind size: a French press is suitable for coarse grinding, filter paper or siphon requires slightly finer, and a moka pot has flexible adjustment space due to different heating sources. Espresso relies even more on a precisely constructed dual-gear coffee grinder to brew a rich, authentic Italian flavor. This article will provide a complete analysis of the grinding essentials for each device and visual judgment techniques for espresso.
Freshness is the first requirement for good coffee, and the second priority is mastering the grind size of coffee beans, which directly affects the extraction effect—that is, the quality and strength of the coffee flavor. In principle, the finer the coffee grounds and the longer the brewing time, the stronger the coffee taste; conversely, the coarser the coffee grounds and the shorter the brewing time, the weaker the taste. The longer the extraction time, the coarser the beans should be ground, to avoid over-extraction and extreme bitterness; the shorter the extraction time, the finer the beans should be ground, to avoid under-extraction.
For example, a French press has an extraction time of about three to four minutes, so coarse grinding is suitable. With a manual hand-crank grinder (commonly known as a bean chopper or propeller grinder), press for seven to ten seconds and then release. If ground too fine, it is easy to taste coffee grounds and a burnt bitter flavor. For filter paper or siphon brewing methods, because the extraction time is relatively short—about one to two minutes—the coffee beans should be ground a bit finer than for a French press, about ten to fifteen seconds, though it is best to use a grinder.
The moka pot is more complicated, related to the heating source used. If it is a gas stove, the heat is fiercer, so it is best to grind coarser to avoid over-extraction. It is recommended to use an induction cooker or alcohol lamp, as the heat is easier to control; otherwise, the moka pot can easily brew a bitter, strong, throat-biting harsh coffee. The extraction time of a moka pot is shorter than that of a French press, filter paper, or siphon, so the coffee grounds should be slightly finer, with a grinding time of about fifteen to twenty seconds. If the heat source is larger, grind coarser; if the heat source is smaller, grind finer—there is considerable flexibility. Summarizing the above points, various brewing methods differ in extraction time, and the required coarseness of coffee grounds also differs. In principle, the shorter the extraction time, the finer the particles should be; the longer the extraction time, the coarser the particles should be.
Espresso Requires a Dual-Gear Grinder
French press, siphon, drip, or moka pot do not have high demands for coffee ground fineness. Blade grinders (commonly known as bean choppers or propeller grinders) cannot adjust the setting; they adjust coarseness by duration, and the coffee particles are uneven in size, making them unsuitable for brewing espresso. It is generally thought that as long as you have an espresso machine, you can brew delicious Italian coffee—this is only half right. The other half depends on a more precisely constructed dual-gear grinder. In this type of grinder, the lower gear is connected to a powerful motor, providing high-speed rotational force, while the upper gear is linked to the setting. Turning it counterclockwise makes the setting reading smaller, and the upper gear descends, narrowing the distance from the lower gear, which means the coffee grounds come out finer. If the upper gear is turned clockwise, the setting value increases, the upper gear rises, widening the gap with the lower gear, so the coffee grounds come out coarser.
A dual-gear grinder sets the coffee ground coarseness by adjusting the height of the gears relative to each other. Do not underestimate this type of grinder—its construction is incredibly precise. Without a dual-gear grinder, it is impossible to brew a rich, authentic espresso.
Visual Assessment of Espresso Quality
Whether an espresso is successful—judging only by flow rate, color, or counting seconds—can achieve only fifty percent accuracy; you must taste it yourself to be sure. Although visual assessment is not very precise, here is a visual reference chart below:
The above content is compiled by CoffeeHunters, a coffee news website.
