How to Eliminate Bitter Astringency in Coffee | Is There Astringency-Free Coffee? Why Your Home-Brewed Coffee Tastes Astringent

What Causes Astringency in Coffee?

Coffee oils and colloids create a smooth mouthfeel, but the polyphenolic compounds in coffee produce a rough astringent sensation. While astringency is an important characteristic in wine, in coffee, it's like an ugly devil's tail running wild in the mouth, creating discomfort.

Why Doesn't This Coffee Have a Silky Texture?

What is "astringency"? Although "astringent taste" is a sensation perceived after tasting in the mouth, it differs from sour, sweet, bitter, or spicy. It's not a taste but rather a tactile sensation, strictly speaking, it should be called "astringent sensation" - a rough, uncomfortable feeling created when polyphenolic compounds in food react with salivary proteins in the mouth. The polyphenolic compounds that cause astringency exist in various fruits, tea, red wine, chocolate, and coffee. Examples like chlorogenic acid, tannic acid, and catechins all belong to the polyphenol class.

In fact, astringency exists in many things, such as tannic acid in red wine, catechins in tea, and when it comes to coffee, it's chlorogenic acid. Both chlorogenic acid and caffeine are mainly products of plants reacting to environmental changes, so the amount of chlorogenic acid also reflects the growth condition of raw beans.

Astringency typically occurs in several situations:

1. Coffee fruits were harvested and processed before they were fully mature;
2. Incomplete dehydration during roasting, uneven roasting;
3. Inclusion of defective beans, such as insect-damaged beans, immature beans;
4. Brewing parameters and techniques.

However, not all astringency is necessarily bad. We categorize astringency into good astringency and bad astringency.

Negative astringency reveals flaws in coffee quality, and astringency generated during the cultivation or processing of coffee is difficult to reverse. For example: leaves mixed in when picking coffee fruits, or fruits picked when not sufficiently mature; during the roasting stage, improper roasting and uneven roasting are also causes of astringency.

But even carefully selected coffee beans will have some degree of astringency within several months after processing. Appropriate astringency can enrich the layers of coffee and make the flavor last longer. If bitterness can be sweet aftertaste and astringency can stimulate saliva, sometimes high-quality bitter and astringent tastes are actually symbols of coffee quality.

From past experience, the earliest new-season beans obtained each year usually have a certain degree of astringency during cupping, and this characteristic precisely indicates that these beans are sufficiently fresh. These freshly processed coffee beans generally take 3-4 months for the astringency to completely fade. Therefore, when tasting these new-season coffee beans, astringency is actually evidence of the freshness of the raw beans.

What Situations Cause Brewed Coffee to Have Astringency? by FrontStreet Coffee

If there's no problem with the roasting, it could be due to the inclusion of defective beans or issues with brewing parameters and techniques.

Therefore, be sure to sort out defective beans before brewing! You must sort out defective beans! You must sort out defective beans!

The main causes of astringency are over-extraction and uneven extraction, which leads to partial over-extraction and partial under-extraction.

Only 30% of the total substances in coffee beans are water-soluble, while the remaining 70% consists of insoluble fibers and carbohydrates. Among these, 20% of the water-soluble substances can bring good flavor to coffee, while 10% of soluble substances have terrible flavors that people avoid. Over-extraction causes the unacceptable bad flavors in coffee to be extracted, becoming a numbing bitterness and astringency on the tongue.

Over-extraction

Over-extraction is mainly characterized by heavy bitterness in the tail section and extraction of impurities, causing bitterness and astringency. High water temperature (or continuous heating of water), too fine grinding or excessive fine powder, and too much stirring can all lead to over-extraction. Sometimes, even in the few seconds we wait for the water in the filter cup to drip down, over-extraction can occur.

Uneven Extraction

Uneven extraction mainly causes flavor imbalance, with excessive acidity leading to a sour-astringent sensation. Uneven water distribution during blooming and brewing can cause partial over-extraction and partial under-extraction of coffee grounds.

Uneven water distribution means the water stream is sometimes thin, sometimes thick, circles are not round, and water injection is asymmetrical. The consequence is that where there's more water, it overflows and penetrates through the filter paper; where there's less water, the coffee grounds cannot be completely wetted, greatly reducing the blooming effect. This ultimately leads to partial over-extraction and partial under-extraction during subsequent water injection and extraction, resulting in mixed flavors and容易出现astringency.

[Tips]

FrontStreet Coffee Tells You How to Distinguish Astringency, Tea Sensation, and Dry Sensation?

Astringency is a tactile sensation or pain sensation. In my opinion, it's an unsmooth tactile feeling, like something dusty, sandy. Astringency and smoothness are the two major mouthfeel characteristics of coffee. Astringency is deducted during cupping, while smoothness gets extra points.

Astringency is not equal to tea sensation. Understanding astringency as tea sensation because some people think tea also has bitterness and astringency, but certain green teas don't have bitter and astringent tastes and have a stronger fresh and sweet feeling. With the correct brewing method and water temperature, you can completely feel no bitterness and astringency, and it's very smooth. For example, we often taste green tea flavors in Geisha, which has tea sensation but no astringency when properly extracted. Similarly, tasting black tea in Sidamo and oolong tea flavors in Costa Rican black honey processing, this tea sensation is slightly bitter, with a long aftertaste in the mouth, where sweetness gradually exceeds bitterness, ultimately ending with sweetness.

Dry sensation generally refers to discomfort in the throat after drinking coffee, causing a dry feeling in the throat, usually called "dryness." There's a similar saying in tea drinking, also called "throat-locking." Dry sensation is mostly because the beans are too fresh or due to uneven dehydration during roasting.

Usually, if astringency appears during the brewing process, why not first feel carefully whether it's bitter-astringent or sour-astringent? If it's bitter-astringent, perhaps it's because too many substances were extracted, you can try adjusting brewing parameters or removing the tail section; if it's sour-astringent, perhaps it's due to uneven extraction, then you need to see if there are areas in brewing techniques that need improvement!

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