Roasted coffee beans turn yellow a burst point to judge the course coffee taste astringency is what is the reason for roasting?

As the title, Qianjie article is mainly for the psychological construction of friends who are about to step into coffee baking. In the first five lessons of "Coffee roasting from scratch", only a very basic roasting theory is explained. The degree of simplicity is probably the "ninety-nine multiplication table" in mathematics.

We must recognize the reality that the theory is often perfect and the reality is often unexpected. For example, when you are familiar with the baking curve theory of the first five lessons in the front street, you have a general understanding of the concepts of bean point, yellowing point, explosion point, firepower, throttle, and time.

When you are sure to practice for the first time, you find that "the brain knows, the hand can't", and the operation is "how the temperature can't keep up", "how to produce so much smoke", "focus on recording the data and forget to regulate and control the firepower." so much so that after several burners, all confidence was lost. It's perfectly normal for this kind of situation. Familiar with the operation of the roaster, the relationship between the adjustment of firepower and throttle and the heating range, and pay attention to the feel. Even if the old master puts on a new stove, it takes two or three stoves to feel it. Therefore, the first point of practice is that we must master the operation of the roaster and simply understand that we can reach the desired temperature by adjusting firepower. (the temperature rise has a lag, and it usually takes 30 seconds to see the effect after adjusting the firepower, so learn to predict.) after passing the "test of roaster operation", please don't be too happy, because at this time you are just a "boiler worker with no emotion". Just like the new driver who just got his driver's license just hit the road, he found that the standard and regular practice he learned in driving school didn't help much on the road. Although at this time you already know the basic theoretical knowledge of baking, and you also know the judgment theory of turning yellow point and one burst point, but in practice, it is "has it changed color", "has it turned yellow", "has it just burst", "how come the second sound is so old yet, and whether the first sound just now is" or am I hearing voices? "

You will doubt your eyesight and hearing. As a novice, the criteria for judging these key nodes should be consistent with everyone as far as possible, otherwise it is easy to "talk to each other" when communicating with others. Qianjie will use words as much as possible to describe the possible miscalculation. In the judgment of turning yellow point, washed coffee is relatively easy to judge, after all, from light green to yellow. However, coffee beans exposed to the sun or anaerobic sun are more difficult to judge, because their raw beans are yellowish, and the color value may not be obvious enough when they turn yellow.

Two indicators are added to the front street below to assist in judgment. The first is the temperature, which generally turns yellow after 150 degrees Celsius; the second is the aroma. Coffee beans have the aroma of grass and wheat before turning yellow, and after turning yellow, these aromas do not come, but will have the aroma of sweet corn.

The judgment of a burst point will affect the overall release time, and our release is based on the development time and temperature after the explosion. Assuming that the explosion time of "your judgment" is later than that of "actual", then under the same development time recorded by everyone, your coffee will be deeper than others'. On the other hand, if the explosion time of "your judgment" is earlier than that of "actual", then under the same development time recorded by everyone, your coffee will be lighter than others', and there may be a stale flavor. (the difference in development time is 20 seconds, and the change of flavor will be very obvious.) Why the "explosion" point is so difficult to judge, Qianjie's judgment for the beginning of the explosion point is the second popping sound in a row. The sound of an explosion is very clear, just like the "crackling" sound made by beating mosquitoes with electric mosquitoes. Qianjie believes that the reason why it is easy to misjudge is that there has been a "false explosion" before the "crackling" sound, which is not so clear, and the sound is heavier, mainly because some defective beans or beans that bake faster are the first to burst. These beans burst because of their own defects, which do not completely absorb heat, and the rest will appear dull. And sporadic coffee beans may be lucky because they are often at the bottom when the drum rotates, which absorbs more heat than other coffee beans, so it takes the lead in cracking, but also sends out a crisp burst sound, but after a sound, the second sound does not come for a long time. It belongs to the "runaway player" and cannot be counted as the first sound of an explosion.

The last thing that makes the novice break the defense is that "I also practice according to the baking curve, and the bean color value also feels good when it comes out of the oven, but when it comes to tasting it, it tastes terrible." this is really crushing. I worked hard to bake a batch of coffee beans that felt good, and waited for the cup test for eight hours in an impatient mood, but it came as a bolt from the blue.

If you encounter this kind of situation at present, please do not be discouraged, "there are thousands of curves that can bake good coffee, and the baking curves are infinite, is it possible that your baking curve is not applicable in the first place?" In the previous baking class, Qianjie also stated that for the baking curve shared online, we should not copy the data, but understand the logic behind the data. Sum up the reasons for each failed baking, plug these defects, and you can find a curve that suits you.