[original] the lighter the roasting of coffee beans, the more sour they drink?

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On weekdays, you can get in touch with all kinds of guests at the bar, a considerable number of whom are not used to the sour taste of coffee, and usually sour coffee is shallow roasted coffee. it is also true that some of the sour taste of shallower roasted coffee is unacceptable. Therefore, guests naturally leave the impression that the shallower the coffee is roasted, the more sour the coffee will be.

So is this really the case?

It depends on the source of the sour taste in the coffee and how these acids change during the baking process.

The sour substances in raw coffee beans are malic acid, citric acid, tartaric acid, chlorogenic acid, phosphoric acid and so on.

During the roasting process of coffee, the sugars and organic acids in beans will begin to be degraded by heat or decomposed into formic acid, acetic acid, lactic acid, fumaric acid, Corninic acid and other acids, but these acids will continue to degrade or volatilize with the deepening of baking degree.

In the baking process, the most dramatic changes in acid quality and acid concentration are the stages of development after the explosion begins. In this way, the acid in coffee reaches its highest value at some point after an explosion and then decreases due to the thermal decomposition or volatilization of the acid.

In fact, at the beginning of an explosion, a large number of organic acids such as formic acid and acetic acid in coffee will be formed, reaching the maximum value at the end of an explosion, and then begin to decrease. On the other hand, organic acids such as citric acid and malic acid will be slowly decomposed with the explosion. Citric acid and malic acid are acids that taste bright and comfortable, while acetic acid and formic acid are volatile, taste sour, smell sour and irritate at high concentrations.

Moreover, after the explosion, the sucrose in the coffee will be slowly consumed in the reaction. So, in fact, coffee tastes the most sour in the medium and shallow roasting stage, while in the very shallow and shallow roasting, because the coffee beans retain more sucrose and the total amount of organic acid is not so large, in fact, there is a very natural sweetness in the soft sour taste, and some raw beans that already contain high sugar content in raw beans will even have a strong sweet feeling if roasted to this stage.

Baked a washed iron pickup truck from Papua New Guinea. Divided into two baking, I tried to make the yellowing point before the explosion and the explosion point are the same, only changed the development time after the explosion.

The first bean is 190.5 degrees at 1:20 seconds after an explosion (a dense middle part of an explosion).

The second one is 191.8 degrees at 1:40 seconds after an explosion (an explosion).

The cup test shows that:

The first one: the taste is soft and sour, and then the sweetness will converge soon. However, the aroma will be relatively simple, there will be a little similar to ginseng flavor.

Second: the entrance acidity will be brighter, the acidity will be higher, the sweetness will appear later, the aroma complexity will be higher, and there will be fruit-like aroma.

Therefore, in fact, it is not that the shallower the roasting degree, the more sour coffee must be, which is related to the complex changes and combinations of all kinds of flavor substances in coffee roasting. But there is no doubt that shallow roasting will give the coffee beans a green taste.