Roasting process of boutique coffee beans and matters needing attention

Roasting is one of the most important factors affecting the taste and flavor of coffee. Baking itself is both a science and an art.

Green coffee beans in the 8-20 minutes of roasting process, will produce a series of complex changes: from the appearance, coffee beans gradually change from light green to light yellow, light brown, brown, dark brown, if it is very dark roasting (such as southern Italy roasting habits), then finally will become the surface of the oil bright black brown; from the chemical change point of view, coffee beans in. Simply put, people are used to dividing coffee beans of different roasting degrees into several different names: City, Full CIty, Espresso, French, etc.

The control of the roasting process of coffee beans is actually a process of removing or masking the original bad taste of coffee beans in order to give full play to the original flavor of coffee. As for later many coffee lovers are keen to prepare their own "mixed beans", the purpose is also to let various origins, different varieties of coffee play their own advantages, and finally get the best taste (accurately speaking, it should be "the most suitable for their own taste").

The complete roasting process of coffee includes three stages: "dehydration","first explosion" and "second explosion", each of which represents different changes in coffee beans at high temperatures. Of course, according to your own needs, you can also decide to end baking at any time.

In the "dehydration" stage, the water in the coffee beans will be fully evaporated, and then the coffee will produce a popping sound, that is, into the "explosion";

In the "explosion" stage, the starch substance in the coffee beans will be saccharified at high temperature, and the unique "caramel taste" that is usually felt when drinking coffee is determined by the control of this stage. At this stage, some light roasted, medium roasted, and medium roasted coffee beans will be roasted one after another.

This is followed by a "second explosion", in which most people end roasting early (within a few dozen seconds of the coffee bean's second explosion) in order to achieve the best "caramel flavor" and a lower level of "sour flavor", which is usually used to make Espresso. However, if you choose to continue roasting, the acidity in the coffee beans will completely disappear, and the sugar substances converted from the previous stage will be further carbonized. As a result, the acidity of the coffee will disappear, the sweetness will be reduced, and the bitterness will be more and more intense. The roasted coffee beans are usually used as a base for fancy coffee in coffee shops except in southern Italy.

After roasting, coffee beans need to be cooled quickly to avoid excessive "self-roasting" of coffee beans. After that, coffee beans will only exert their best flavor after being properly preserved for one day.

What needs reminding is: Coffee beans of different varieties and origins have their own "best roasting degree" according to their characteristics, and some responsible coffee bean suppliers will tell buyers the "recommended roasting degree" and "coffee flavor characteristics" of these beans to avoid the original characteristics of some high-quality coffee beans being destroyed by improper roasting methods (for example, Costa Rica coffee beans are known for their rich, bright acidity, but if they are over-roasted, these characteristics will be destroyed). Of course, for coffee enthusiasts, constant experimentation and innovation is also a rare pleasure. The concept and principle of coffee roasting As the name suggests, roasting is to provide heat to coffee beans, causing a series of chemical changes within them. Green coffee beans through roasting, showing coffee unique color, flavor and taste. Each coffee bean contains flavor, sourness, sweetness and bitterness. How to release it depends on the roasting temperature.

Roasting is an important step in the long journey of each coffee bean, from the bland green bean to the lingering aroma of the cup. Coffee beans in this field for about 20 minutes (inversely proportional to the temperature), temperature as high as more than 200 degrees Celsius, in the process of intense dialogue with the fire, through many chemical changes.

First of all, starch in raw beans will be converted into sugar and acidic substances due to high temperature, while cellulose and other substances will be carbonized to varying degrees. Water and carbon dioxide evaporate, and protein is converted into enzymes, which combine with the rest of the fat to form an oil film on the surface of the beans. Coffee beans expand during roasting, making a pop-like noise and losing moisture. But because the outer skin of coffee beans is very tough, we usually don't see coffee beans crack like popcorn. From raw beans, light roasting, medium roasting to deep roasting, water is released again and again, weight is reduced, volume is slowly expanded, color of coffee beans deepens, fragrant oil is gradually released, and texture becomes crisp.

Green beans contain a large amount of chloric acid, which gradually disappears during baking, releasing familiar and pleasant fruit acids such as acetic acid, citric acid and malic acid contained in wine. Baking is beneficial to present these acids in moderation.

We often see roasted coffee beans with different shades of color, on the one hand, this may be due to different types of single-serve coffee beans; on the other hand, the main reason for this color difference is the degree of roasting. In the most colloquial language, the degree of roasting can be interpreted as the degree of heat at which it is baked. To take the classic example of carbon-roasted coffee, this is a French roast in which the beans are highly carbonized, dark brown in color and carbon black in color due to the depth of the roast (either due to the high temperature of the roast, or due to the length of the roast, or both, depending on the circumstances). Carbonized coffee is generally believed to taste bitter, not only from caffeine, but more from carbonized coffee beans.

Principles of baking: The most important thing about baking is to be able to cook the beans evenly inside and outside. First of all, the water in the beans will be smoothly discharged through the fire. If this step is too hasty, it will have spots and taste astringent.

80% of coffee taste depends on roasting, so roasting is an important process in brewing good coffee.

If the baking technique is good, the beans will be large and swollen, the surface will not be wrinkled, and the luster will be balanced. Roasting coffee beans to their ultimate character is the ultimate goal of roasting. Coffee roasting process and stage characteristics The flavor of coffee depends on the variety of coffee, and roasting is also a decisive factor.

Basically, coffee roasting is a high-temperature coking process that completely changes the substances inside the green beans, producing new compounds and recombining them to form aromas and alcohol flavors. This effect only occurs at high temperatures, and if only low temperatures are used, decomposition cannot be caused, and no matter how long the coffee beans are baked, they will not be cooked. 1. Baking process Most people think that baking is nothing, just frying raw beans with fire. In fact, roasting is the most difficult step in coffee processing. It is a science and an art, so experienced roasters enjoy a highly respected position in Europe and America. The baking process can be divided into three stages:

1. Drying

At the beginning of baking, green beans begin to absorb heat, and the water inside gradually evaporates. At this time, the color gradually changed from green to yellow or light brown, and the silver film began to fall off, you can smell the faint smell of grass. The main function of this stage is to remove water, which accounts for about half of the roasting time. Since water is a good heat conductor, it helps to roast the internal substances of coffee beans. So, although the goal is to remove water, bakers use the temperature of the water and control it so that it does not evaporate too quickly; usually, it is best to control the water to reach the boiling point in 10 minutes and turn into steam. At this point, the internal substances are fully cooked, and the water begins to evaporate, washing out the outside of the coffee bean.

2, high temperature decomposition

Roast to about 160 degrees Celsius, the moisture inside the beans evaporates into gas, which begins to rush out of the beans. At this time, the inside of the raw beans changed from endothermic to exothermic, and the first cracking sound appeared. After the crack, it will turn to heat absorption, when the pressure inside the coffee bean is extremely high, up to 25 atmospheres. The heat and pressure begin to break down the original tissue, forming new compounds that create the taste and flavor of coffee; at about 190 degrees Celsius, the conversion between endothermic and exothermic occurs again. Of course, pyrolysis continues to occur, and coffee beans turn from brown to dark brown and gradually enter the stage of heavy roasting.

3. Cooling

Coffee must be cooled immediately after roasting to quickly stop pyrolysis and lock in flavor. Otherwise, the high temperature inside the beans, if it continues to act, will burn off the aromatic substances. There are two cooling methods: one is air-cooled; the other is water-cooled. Air-cooled coffee requires a lot of cool air to cool the beans quickly in 3-5 minutes. In the field of professional roasting, large roasters are equipped with a tray with a rotatable push arm; when roasting is completed, the beans are automatically fed into the tray, and the fan at the bottom of the tray is immediately activated to blow cold air, and the coffee beans are stirred by the push arm to cool them. Water-cooled coffee is slow, but clean and pollution-free, and retains the aroma of coffee. It is used by specialty coffee makers. Water-cooled coffee beans are sprayed with a mist on the surface, allowing the temperature to drop rapidly. Because the amount of water sprayed is important, it requires precise calculation and control, and it increases the weight of baked beans, which is generally used for large commercial roasting. Second, the degree of baking and characteristics From the point of view of baking degree, the deeper the baking degree, the stronger the bitterness; the lighter the baking degree, the stronger the sour taste. The degree of roasting depends on the characteristics of the coffee beans themselves. For coffee beans with strong bitterness and light acidity, moderate and light roasting degree is generally selected.

1. Light baking

The mildest fried culture, no flavor and concentration at all, beans are not ripe, green taste of raw beans, not suitable for grinding drinking. Generally used for testing.

2. Deep shallow baking (Cinnamon)

Also known as cinnamon baking, for the general popular frying degree, leaving a strong sour taste. Bean color is quite close to cinnamon, so it is also called cinnamon baking, sour emphasis. It is popular with western Americans.

3, lighter medium baking (Media)

Deepen the color, easy to extract the original flavor of coffee beans, mellow, sour and delicious. It is mainly used to mix coffee.

4. Medium baking (High)

Coffee tastes stronger and less sour, which is how coffee beans are generally roasted. Acid neutral and bitter, suitable for coffee such as Blue Mountain and Gili Mazaro. It is loved by Japanese and Nordic people.

5. Deep medium baking (City)

Also known as city baking, bitter acid is thick, almost no sour, unique flavor. Coffee suitable for Colombia and Brazil, loved by New Yorkers.

6. Normal baking (Full City)

Also known as all-city roast, it is suitable for brewing iced coffee. No sour, mainly bitter, bitter will be aggravated, but high-quality beans will have sweet taste. It is used for iced coffee and is preferred by Central and South Americans.

7. French baking

French baking method, slightly black color, bitter strong, but also exudes oil, bitterness and concentration are deepened. Coffee brewed in a steam press.

8. Deep baking (Italian)

Also known as Italian baking, the deepest degree of baking, beans black and translucent, surface oil oozing, bitter very strong. At this stage, the coffee beans have been severely carbonized, and the taste of one coffee bean and another coffee bean has been difficult to distinguish. For Italian steam coffee. 3. Baking characteristics around the world Cities around the world have their preferred baking tendencies.

In Tokyo, slightly deeper medium roasts are more popular, but slowly there is a trend towards deeper roasts as well. In the West, deep baking has been popular since ancient times.

New York, as its name suggests, tends to prefer urban roasting, but because of the variety of people living in the city, coffee beans of different roasting degrees are sold, and the variety is quite rich.

Vienna prefers deep baking. French people prefer French baking; Italians often use Italian baking.

However, in recent years, Europeans and Americans have widely used Italian roasts (Brazil and Italy most commonly used deep roast), and the variety is also colorful, and steam pressure machine coffee is still loved by people.

Deep roasting Ethiopian coffee beans would be wasteful. Because that would lose the distinctive character of the coffee. It's also not good to roast Yauco Specialty and Kona beans black, because then you lose the classic flavor you were looking for when you bought it.

Some coffee beans will develop new and interesting qualities when roasted black. Mexican coffee beans produce an interesting sweet taste when roasted black.

Guatemala Antigua coffee beans tend to retain their acidity and fruity flavor when deeply roasted, which is difficult for other coffees.

Sumatra coffee beans are usually full, but less acidic than medium, and when roasted deeply, they lose their acidity and tend to turn into a sugary paste.

In general, the darker the roast, the lower the quality. A deeper roast means that most of the flavor of the coffee beans will be lost. Roasting coffee beans and coffee-related activities at home is the most difficult to roast coffee beans at home. When brewing high-quality coffee, the freshness of the beans is crucial.

The easiest way is to roast coffee beans in an oven. The biggest benefit of doing this is that you can adjust the temperature and not let your home smell of roast coffee. Heat the oven to 230 degrees beforehand. Remember to keep air flowing between coffee beans and not spread them too thick. After baking for about 10 minutes, observe the color change. Listen for the crackle of coffee beans and check the color at all times. When the beans are only slightly lighter than you want, remove them from the oven and cool them. The residual heat will keep the coffee beans warm for 2-4 minutes.

Home baking ovens can also be used, but the best are traditional pan or popcorn models. A handle operates two vertical metal blades inside the machine that rotate the beans as they roast. This can be bought at secondhand stores or good kitchen appliance stores, where you can also buy inexpensive oven thermometers.

When the coffee is done, remove it from the roaster and place it in a heatproof bowl. Place the bowl by a window or outdoors.