What is coffee roasting? What are the terms related to one explosion and two explosions?

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Fresh coffee beans are emerald green. Raw beans must be roasted, ground and then brewed before they become coffee in our cup. Unbaked raw beans smell only a little grassy and slightly fruity, but almost tasteless. With regard to the importance of coffee roasting, there is a saying that the baker determines 80% of the flavor, while the pot coffee thinks that the nature of the raw beans is good enough, and the baker will want to retain more local layers of origin, so the closer it is to the flavor of the producing area, it is not easy to take into account the roaster's baking style.

Baking, in short, is heating coffee beans for life. Heating will change and transform the chemical composition of raw beans, for example, starch will be converted into sugars and acids, plant fibers will be carbonized to a certain extent, water and carbon dioxide will volatilize, and proteins will become enzymes. The rest of the fat will be combined to form what we collectively call coffee oil. Coffee oil, a volatile substance, is precisely the source of coffee aroma, and because coffee oil can dissolve in water, roasted coffee beans can be ground and brewed into fragrant coffee in our hands.

There are two very important stages to recognize in baking.

An explosion: the water and other substances in coffee beans produce carbon dioxide due to heat, so the cell wall is broken and the explosion is loud.

The second explosion: two minutes after the end of the first explosion, the temperature rose above 200 degrees. "here, because each roaster is different, the definition of temperature can only be approximate rather than accurate." the cell wall of coffee beans disintegrates, and the oil in the beans will spill at this time.

The first explosion and the second explosion can express the collapse of the cell wall of coffee beans, thus evaluating the chemical changes and the release of aromatic substances in the beans. The baking degree is traditionally determined by the time of the second explosion. SCAA has also introduced an Agtron color card to compare the caramel degree to make the baking degree more accurate.

According to the different heating time and speed, it can be divided into different baking degrees. The most common and easiest method is to divide it into three categories: shallow, medium and deep, which are as follows:

Cinnamon Roast: light baking, also known as cinnamon baking, Agtron No.85

Time to drop beans: an explosion begins to be dense.

Wind taste: the bean surface is cinnamon color, at this time the smell of grass has been removed, strong acidity, slightly fragrant, often used to make American coffee.

Special point: in recent years, the trend of boutique coffee is mostly towards shallow roasting, because shallow roasting can retain the most acidity and aroma, but also retain the most flavor from the producing areas, that is, the growing environment of coffee, which brings beans a unique personality. Coffee beans appear light brown in appearance and will not have a glossy finish.

Medium Roast: medium baking, also known as "micro baking", Agtron No.75

Time to drop beans: from the explosion to the end

Wind taste: the bean surface is chestnut color, light taste, slightly sour with bitter, moderate aroma, retain the original flavor of coffee beans, often used as American coffee or mixed coffee.

Special point: coffee beans to the degree of roasting, will begin to produce "caramelization" phenomenon, the acid begins to weaken, mellow taste stronger, and therefore more sweet, coffee bean surface will be a little bit out of oil.

Full City Roast: micro-depth baking, namely deep baking, also known as "deep city baking", Agtron No.45

Time to drop the beans: the second burst

Wind taste: the bean surface is brown, the taste is calm and full, the bitter taste is strong, the aftertaste is sweet, the aroma is full, it is a Central and South American baking method, and more iced coffee and black coffee are used.

Special point: the deeper the baking, the more you need to rely on the experience and skills of the baker, so the more you can show the personal color of the baker, usually with a thick taste and throat rhyme. The deeper the baking, the more obvious the bitterness, and the bean surface will be glossy, dark brown, or even close to charcoal black.

In addition to these three, there are several relative subdivisions, such as:

Light Roast: very shallow baking, also known as "shallow baking", Agtron No.95

Time to drop beans: before and after the start of the explosion

Wind taste: the bean table is light cinnamon color, with a strong grass flavor, taste and aroma is not enough, generally used in experiments, rarely used as a product.

High Roast: moderate micro-deep baking, also known as "concentration baking", Agtron No.65

Time to drop beans: the end of the first burst

Wind taste: the bean surface is light reddish brown, the taste is refreshing and rich, the sour and bitter balance is not irritating, and it is slightly sweet, with good aroma and flavor. Blue Mountain and Gillimazaro coffee are suitable for this roasting degree and are loved by people in Japan and Central and Northern Europe.

City Roast: medium and deep baking, also known as "urban baking", Agtron No.55

Time to drop the beans: after the first burst, that is, between the first and second bursts.

Wind taste: the bean surface is light brown, the taste is bright and lively, the acidity between sour and bitter balance is light, and it releases the high-quality flavor of the coffee, which is the standard baking degree and the public's favorite roasting degree. Brazilian and Colombian coffee are suitable for this roasting degree and are often used in French coffee.

French Roast: deep baking, also known as "French baking", Agtron No.35

Time to drop beans: the second explosion is dense to the end of the second explosion.

Wind taste: the bean is dark brown and black, strong taste, bitter taste, sour taste almost no feeling, with strong chocolate and smoke aroma, for Europe by the most popular in France, more coffee Oulei, Viennese coffee.

Italian Roast: extremely deep baking, also known as "semantic baking", Agtron No.25

Time to drop the bean: the second explosion ends until the bean surface turns black and produces oil.

Wind: the bean surface is black and glossy. Before carbonation, the coffee bean fiber has a strong, complex, bitter taste, with a strong fried and scorched aroma. It is mainly popular in Latin countries and Italy. It is often used as Italian coffee Espresso.

Because of their different characteristics, different beans can show completely different flavors with proper baking methods.

If you go to a coffee shop and there happens to be a bean roaster, it's easy to hear beans beeping as they are roasted. Coffee beans have two opportunities to make a sound when they are heated, which are called "first explosion" and "second explosion" (First Crack and Second Crack).

First explosion of First Crack

This is because of the heat, which produces a large amount of gas and water vapor inside the beans. when the internal pressure cannot hold up, the volume of the beans expands and then bursts. An explosion occurs when the baking temperature is about 196Mel 205 °C, and the sound is so loud that it sounds a bit like popcorn, judging that the beans have begun to reach the level of shallow baking. Between the first explosion and the second explosion, it belongs to medium baking.

Second explosion Second Crack

If the heating continues at this time, a relatively subtle sound belonging to the second explosion will be heard while the temperature continues to rise, and the baking temperature is about 225mi 230 °C. After the second explosion begins, the oil of the beans will surface, that is, the stage of deep baking. Curious you may wonder what will happen if you continue to bake. Of course, because of carbonization, it finally burned up.

Cooling

Roasted coffee beans must be cooled quickly to prevent self-baking. Professional bean roasting machines on the market now have special cooling trays, but when roasting in large quantities in multiple batches, it is still necessary to pay attention to the change of coffee temperature after roasting.

Static

Roasted coffee beans have different resting time requirements depending on the heating mode of the roasting machine, just like fried steak, the coffee flavor will be better after the roasting!

Once the coffee bean is ground into powder, it will oxidize rapidly because of its larger contact with the air, and sometimes it will smell sour because of the oil it contains, so proper grinding is also related to the success or failure of a cup of coffee. Grind the coffee before brewing in order to retain the aroma of the coffee.

Different coffee brewing utensils need different grinding degrees, too coarse particles can not extract the taste, too fine and easy to over-extract, resulting in bitter taste, so the suitable extraction can extract the good ingredients of the coffee completely, and the inferior substances are retained in the fiber quality. generally speaking, the shorter the brewing time, the more the coffee powder must expand the surface area to contact with the water, and the finer the particles required. On the contrary, if the cooking time is prolonged, the larger the grinding particles must be, the rougher the grinding particles must be, so as not to extract unnecessary impurities. For example, a fast-extracted Espresso requires extremely fine grinding like a fine powder, and a rough grind is required in order to fully infiltrate the coffee to release its aroma.