Why is light roast coffee a bit sour?

Some people say that it is so sour because of the light roasting process, which retains the fruit acid and more ingredients. Why is it not sour, sweet and smooth at the same time? What about sweetness and fat?

That is because the powder is more finely ground, the water is temperature high and the water flow slow. Try to reduce the extraction concentration in the first half process, and you will get the flavor of the second half. But making it too low will only get you a glass of sweet drink with subpar coffee quality.

The degree of roasting and the length of roasting time will affect the weight loss ratio of the coffee. The moisture in the green beans accounts for about 11%, and the moisture in the roasted beans accounts for just around 2%. Therefore, the weight loss ratio of water is about 9%, while the weight loss ratio of raw beans and cooked beans is 13%-17%, and the proportion of water is deducted by 9%, so the weight loss of other components of coffee beans is about 4%-8%. That is, there is a 4% difference in ingredients -- it seems like a lot, right?

In fact, it is a lot worse. So, some dark roasted beans need to be extracted at a ratio of 1:13 to taste good (such as Blue Mountain), and some light roasted beans need to be extracted at 1:18 or even 1:20 to achieve a balanced proportion.

Generally, light cultivated beans will have a more refreshing flavor, and the flavor is very rich. The medium roast is a more balanced expression with a refreshing flavor and heavy mouthfeel. Deep-roasted beans are more representative of their taste, and their usual flavors are stronger, such as smoke, chocolate, and woody flavors, and there will a thick taste along with it.


 The classification of these three roasting methods is only very general. In fact, many factors, such as the style of the roaster of the bean origin variety, can affect the roasting, which is merely a general statement. A professional barista will adjust the roasting curve according to the characteristics of each bean. The flavor of the pot is different from one degree or 2 seconds.

Generally speaking, the soluble matter of coffee is about 30%. Among them, 20% are the good ingredients we love to extract, and the other 10% are the bad and astringent ingredients. But there are always exceptions. If there are coffee beans with good flavor even in the last 10%, should they also be extracted to make a cup of coffee with complete flavor?

After brewing a cup of so-called specialty coffee, try breaking the powder bed and smell it to see if the coffee grounds still smell good?


If so, try adding the same amount of hot water with the same amount of powder to see how it tastes.

If it still has flavor, pour it into the previous cup of coffee to see if the flavor is more complete. Then smell it again to see if the coffee grounds still have aroma. Repeat this until you can feel there is a bad taste, so you can know how much the extractable rate of this specialty coffee is, or how much water to powder ratio to be extracted for balanced flavor and taste.

Finally, the coffee powder doesn't have to be too much, the grinding doesn't have to be fine, the water temperature doesn't have to be high, the water flow doesn't have to be fine, and of course, the coffee doesn't have to be strong.