How to Judge Coffee Extraction Through Tasting: An Introduction to Hand-Pour Coffee Brewing Flavor Sensory Description

If you want to learn how to brew coffee, you must first learn how to drink coffee. Of course, "learning to drink coffee" here doesn't mean being able to describe exquisite flavors, but rather being able to judge whether a cup of coffee is good or bad—in other words, whether it's tasty or not.

Subjective and Objective

Whether coffee tastes good or not depends largely on personal preference. For example, when FrontStreet Coffee was sharing and tasting coffee with various customers at the store, some customers found the same coffee so sour that it made their teeth chatter, while others found it full of sweetness and very delicious. From their perspectives, their judgments of taste were all correct, which demonstrates the difference thresholds in taste perception between individuals.

If everyone judged according to their own standards, chaos would ensue. Therefore, there is a relatively objective standard that allows people to learn this system and communicate with each other. These standards are the sensory standards established by some mainstream organizations (such as SCA, ACE, CQI). These standards are largely similar and represent the current mainstream perception of coffee sensory evaluation. (If you want to learn, you don't necessarily need to take courses—you can first purchase some sensory-related books for study, and only consider courses when you truly need them.)

Finding Differences Through Comparison

Once, when FrontStreet Coffee was conducting a test on "the impact of filter paper fit on coffee flavor," a customer happened to be drinking coffee at the store. So FrontStreet Coffee invited this customer to participate in the tasting. Through comparative tasting of samples, the customer was able to accurately describe the differences between these three cups of coffee.

Therefore, learning to drink coffee requires accumulating an effective flavor information database, and comparative tasting is one of the more efficient methods. The second requirement is sufficient accumulation. For example, when you taste a coffee with acidity that refreshes your perception, your threshold for coffee acidity expands, which in turn affects your description of coffee's sour flavors.

Distinguishing Positive and Negative Flavors

Even if you don't like sour coffee, flavors like lemon acidity, passion fruit acidity, and grape acidity all belong to positive flavors. The same applies to bitterness—some bitterness like that of dark chocolate is also considered a positive flavor. (Anyone who has eaten pure dark chocolate knows that kind of bitterness is extraordinary.)

So what are negative flavors? Generally speaking, they are unpleasant tastes, such as strong acidity, intense bitterness, sharp acidity, burnt bitterness, astringency, bitter aftertaste, and long bitter finish. Some non-taste negative sensations include hollowness, blandness, coarse texture, and short aftertaste.

These negative flavor manifestations stem from issues with coffee bean quality, roasting quality, or brewing problems. By choosing reliable coffee brands, you can basically avoid problems with coffee bean quality and roasting. What remains are negative flavors caused by brewing reasons.

Brewing problems can be roughly categorized as under-extraction and over-extraction. For example, under-extraction leads to negative manifestations such as strong acidity, sharp acidity, astringency, light saltiness, thin texture, watery consistency, and short aftertaste. Over-extraction leads to burnt bitterness, astringency, long bitter finish, coarse texture, and so on. Therefore, as long as we can distinguish these flavors in coffee, we can infer what causes in brewing led to these negative flavors, thereby using taste to determine the extraction status of coffee.

Under-Extraction

Under-extraction generally occurs when sweet and bitter substances are not extracted, resulting in obvious acidity, and even a sharp, stimulating sour sensation. If it's a strong sour sensation, it might be caused by using too little water. Sharp acidity and other stimulating sensations, watery consistency, and thin texture might be caused by relatively coarse grind size combined with fast water pouring, leading to short extraction time.

Fortunately tasting a light saltiness is also a manifestation of under-extraction. Under normal circumstances, it's rare to taste saltiness in coffee because it's masked by acidity and sweetness. However, in under-extracted coffee, the lack of sweet masking allows the saltiness to emerge, typically appearing in some under-extracted coffees with less obvious acidity.

Under-extracted coffee also often exhibits a short aftertaste. Generally, the aftertaste is provided by the middle and later stages of coffee extraction. If this part is missing, the coffee's aftertaste will be short.

What situations easily cause under-extraction?

When we clearly perceive that coffee is under-extracted, what usually comes to mind first are problems such as grind size being too coarse, water temperature being too low, coffee-to-water ratio being too large, and contact time between coffee grounds and water being too short, which lead to low flavor concentration. In reality, high concentration is also one of the manifestations of under-extraction. For example, some people are accustomed to using less water to brew more coffee grounds, only extracting the flavors from the first half, while the flavors from the second half remain in the coffee grounds. Combined with high concentration, the initial taste is often both strong and sour.

When the coffee bed in pour-over coffee exhibits channeling—meaning the water level is too high during pouring, breaking through the coffee grounds wall or overflowing over the grounds wall, with water flowing along the filter cup's ridges—the coffee liquid that falls into the lower pot is certainly under-extracted. The blooming stage is meant to prepare coffee for flavor extraction. Therefore, uneven water distribution during blooming can lead to different dissolution rates in localized areas of the coffee grounds, with unwetted particles requiring more time to fully release flavors.

Over-Extraction

Over-extraction, on the other hand, is caused by extracting too many coffee substances, leading to some unpleasant bitterness also being extracted into the coffee. For example, the astringent taste that appears due to too fine grinding or too long steeping time is not just bitter—it makes the entire mouthfeel coarse. This is because over-extracted coffee contains more polyphenolic substances, which bind with proteins in saliva, causing a coarse sensation. Water temperature that's too high can easily cause coffee to develop a burnt bitterness. This bitterness is very stimulating and lingers in the mouth for a long time. From FrontStreet Coffee's experience, the appearance of such flavors is mostly due to too many fine particles or too fine water flow causing coffee to steep for too long or water temperature being too high. The solution is to adjust to a coarser grind or lower the water temperature.

Of course, under normal circumstances, properly extracted coffee will exhibit fruit-like acidity, such as the bright acidity of lemon and citrus, or fruit tones like strawberry and plum that are balanced between sweet and sour. Then there's full sweetness, like honey or fructose. Moderate concentration presents clear flavors and rich layers. As well as a persistent aftertaste, generally表现为 light floral notes and tea-like sensations.

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