The Myth about the taste of Coffee-- discussion on the astringency in Coffee

The acidity of the cups made by the students is somewhat strong, and the acidity seems to be dissociated from the bitter taste, and the overall balance is greatly reduced, and it is mainly strong bitterness after the acid. At this time, the problem came out-she felt the obvious astringency in several cups, and I always thought it was not astringency but a sour sting taste produced by a combination of strong acid and strong bitterness. Explain for a long time, but I am not sure whether the astringency she said is the kind of acerbity I perceive, and there are a lot of myths about astringency, one of the most troublesome tastes of coffee.

First of all: what is the astringent taste? Is it a smell? Or is it like sour, bitter, sweet and salty that can be perceived by the sense of taste?

Second: how does the astringency of coffee come into being?

Third: what is the way to reduce or avoid astringency?

With these myths to check some data, although it does not completely solve the problem, but the theoretical explanation of astringency does verify some problems in the operation.

First of all: astringency is a kind of taste, not taste. The American Society for testing and Materials (ASTM) defines astringency as the compound sensation of wrinkling and contraction caused by epithelial cell leakage in alum or tannin solution. Astringency is a complex feeling that involves the dryness and roughness of the oral surface, as well as the tightening, dragging or wrinkling sensation of mucous membranes and muscles in the mouth. It is generally believed that astringency is sensed by tactile mechanoreceptors and transmitted by the free nerve endings of the trigeminal nerve, so it is a diffuse, unstable sensation. Its sensory characteristics are often described as wrinkled, rough or dry taste.

The long and obscure academic definition above may be a little difficult to understand, but to take a small example: if we eat persimmons fully ripe, we will easily feel sweet, but if not ripe, the tip of our tongue will soon be stuck by some substance in the persimmon pulp, and our tongue will feel dry and astringent. The way astringency is perceived is different from the perception of the four basic tastes, sweet, sour, bitter and salty. It is not a sense of taste but a sense of touch.

So, how does astringency come from? It depends on the composition of the coffee. Coffee beans themselves contain tannins (Tznin) and chlorogenic acid-all of which are sour and astringent. Tannins are a major cause of astringency in coffee. However, all raw beans contain tannins, why not all coffee is astringent?

Here depends on the three major links that determine the taste of coffee. Raw beans, baking and extraction.

In the raw bean section, high-quality Arabica generally has lower tannin content than Robosta, and the chance of astringency is relatively small. Of course, according to different varieties, soil, climate and other planting conditions will be different, but in the fruit picking, those immature fruits are more likely to produce astringency. Therefore, high-quality high-quality beans should only pick ripe fruits.

If the baking part is well controlled, the substances in the coffee beans can be transformed properly, and the sweetness and bitterness can be properly played and the astringency can be avoided. But improper roasting may bring most of the astringency into play, coupled with the lack of adequate response to other flavors, resulting in bitter and astringent coffee. The astringency produced in baking is difficult to be remedied in the later extraction process.

Even if astringency is avoided in baking, there is no guarantee that the extraction will come naturally-astringency is a very tenacious factor, and too low water temperature and excessive extraction will bring it back into the cup.

There is also one thing to note here: everyone's taste system is different, so the perception of astringency will be different, especially the perception of astringency intensity, and sometimes even can not perceive astringency when the body is uncomfortable. or confuse it with sour, bitter and other tastes. The reason is very simple, it's also sour oranges-sour oranges are too sour for some people to eat, while others eat them with relish, and when we have a cold and fever, we always feel that even fresh apple oranges lack the usual sweet and sour taste. That's because the taste buds of our tongues are resting and can't sense the taste normally.

So, how to reduce astringency or avoid the occurrence of astringency? I haven't found a complete answer to this question either. When there is that frustrating, faint but lingering astringency in the cup, how I look forward to which immortals can suddenly show up and give me some advice-but this high-tech society has long scared the gods away!

According to the previous analysis of the three stages of raw beans, roasting and extraction, the probability of astringency is very high, because except for fine coffee, most commercial beans cannot guarantee that only ripe fruits can be picked, and even good raw beans, there is also a great chance of astringency after baking, and water temperature and correct operation are new variables in the extraction.

Therefore, try to ensure that the previous link to control the astringent taste, perhaps the chances of getting a cup of pure non-astringent coffee will be higher!

Source:

The blog of the world of coffee with two bottles of water