Knowledge of coffee roasting

Roasting: As the name suggests, it is to provide heat to coffee beans, causing a series of chemical changes in their interior, presenting coffee's unique color, aroma and taste. Each coffee bean contains flavor, sourness, sweetness and bitterness. How to release them depends on the roasting temperature.

Coffee beans begin the caramelization process between 170-200 degrees Celsius. At high temperatures of 185-240 degrees Celsius, sugars combine with amino acids, peptides and proteins to caramelize, which is known as the "Maillard's reaction".

1. Starch is converted into sugar and acid by high temperature.

2. Fibers and other substances will be carbonized to varying degrees.

3. Water and carbon dioxide evaporate.

4. The protein is converted into enzymes, which combine with the rest of the fat to form an oil film on the surface of the beans.

5. Weight loss, but slowly expand the volume of bulging, coffee beans color deepened, aromatic oil gradually released, the texture has become crisp.

6. As the baking progresses, the chloric acid gradually disappears, releasing the familiar and pleasant fruit acids.

The most important thing about baking is to be able to cook the beans evenly inside and outside

Purpose of roasting: 1. Aroma enhancement, 2. Flavor complexity, 3. Color acquisition, 4. Flavor development

Eighty percent of the taste of coffee depends on roasting, so good roasting is an important part of making 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 character is the ultimate goal of roasting.

The flavor of coffee depends not only on the variety of coffee, but also on roasting. During roasting, coffee beans increase in volume by at least half, while their weight decreases by a fifth.

The darker the roast, the stronger the bitterness; the lighter the roast, the stronger the sourness). The degree of roasting depends on the characteristics of the coffee beans themselves.

Baking degree and characteristics

1, light baking (Light) The lightest baking, no fragrance and concentration at all, beans are not ripe, green taste of raw beans, not suitable for grinding and drinking, generally used as a test.

2, the deeper light baking (Cinnamon) is also known as cinnamon baking, for the general popular baking degree, leaving a strong sour taste. American western preference.

3, lighter medium roast (Media) color deepened, it is easier to extract the original flavor of coffee beans, mellow, sour and delicious. It is mainly used to mix coffee.

4, medium roast (High) coffee bitter more intense, sour lighter, this is the general method of roasting coffee beans. Acid neutral and bitter, suitable for coffee such as Blue Mountain and Gili Mazaro. It is loved by Japanese and Nordic people.

5, the deeper moderate baking (City) is also known as urban baking, bitter acid is thick, almost no sour, unique flavor. Coffee suitable for Colombia and Brazil, popular with urban consumers.

6, normal baking (Full City), also known as the whole city baking, 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) French-style baking method, color slightly black, bitter strong, but also exudes oil, bitterness and concentration are deepened. Such as charcoal coffee, more for steam pressurizer brewed coffee.

8, deep baking (Italian), also known as Italian baking, the deepest degree of baking, beans black and translucent, the surface has oil oozing, bitter taste is 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 high temperature high pressure coffee.

Direct fire is the direct heating of coffee beans with a flame. Evolution so far, but also includes infrared and electric heating tube. Direct-fire roasting usually involves stirring the beans because there is less room to stir. It takes more than ten minutes for coffee beans to be roasted. Because the temperature rises slowly, the caramelization of coffee beans will be very complete, and the flavor will be more complex and compact than that of airflow. This was the greatest advantage of the straight fire style. It would become less and less available on the market now, and it would slowly be eliminated.

Semi-direct fire roasting is actually similar to direct fire roasting, the flame will not directly contact the coffee beans, but also added to the exhaust equipment, another function of this exhaust equipment is to remove the silver skin (attached to the outer layer of coffee seeds film) suction out, to avoid silver skin in the roasting chamber because of high temperature and combustion, and thus affect the taste of coffee beans (some so-called charcoal coffee is deliberately not discharged silver skin, so that coffee beans stained with smoke scorched smell).

Airflow roaster is like a hair dryer, using a fan to suck in air, and then let the air pass through a heating coil to raise its temperature, using air flow as a heating source to roast coffee beans, hot air flow can not only provide the required temperature for roasting, but also use the power of air flow to stir coffee beans, killing two birds with one stone. The advantage of the airflow type is that the heating efficiency is high, so the baking time is short. Large baking factories like to use this method. This baking method is the mainstream on the market now.

The grinding of roasted coffee beans is called grinding.

Grinding into a proper coffee powder is very important for making a good cup of coffee, because the extraction of water-soluble substances in coffee powder has its ideal time, if the powder is very fine, and the extraction time is long, resulting in excessive extraction, the coffee may be very bitter and lose aroma; Conversely, if the powder is very coarse and the extraction time is short, resulting in insufficient extraction, then the coffee will be tasteless, because there is no time to dissolve the water-soluble substances in the powder.

Principles of grinding

1. The ideal time to grind coffee is before brewing.

2. The grinding degree suitable for brewing method should be selected, that is, what thickness is used for what utensils.

3. After grinding coffee powder to uniform, if uneven proof grinder blade wear.

4. The temperature generated during grinding should be low. If grinding heat is generated, put a semi-dry towel on the motor to cool down.

Coffee beans grinding methods can be divided into coarse grinding, medium grinding and fine grinding according to their size.

Use appropriate grinding methods depending on coffee equipment. There is also a medium fine grind or a very fine grind finer than fine grind (into powdered coffee powder).

1, fine grind (Fine grind): fine particles, like the size of sugar.

2, medium grind (Medium grind): the size of particles coarser than granulated sugar and finer than coarse white sugar.

3, coarse grinding (Regular grind): coarse particles, like the size of coarse white sugar.

The grinding tool for coffee beans is a bean grinder. There are three types of bean grinders:

(1)Household manual rotary bean grinder. Suitable for leisure people with small demand, large particles and plenty of time.

(2)Electric bean grinder for home use. It can grind coffee powder of various particle sizes, and can grind 6 people at a time.

(3)Professional electric bean grinder. For commercial use, it can grind out about a pound of coffee powder at a time.

Therefore, if you use a home-style manual grinder, rotate it gently so that it does not generate frictional heat as much as possible. To sum up, if you consider the quality of ground beans, the amount of ground beans, and the use of time and convenience, the use of household electric grinder will be the best choice.

The most common one on the market is a saw-tooth electric grinder. There are two types of sharpeners for saw-tooth grinding machines: one is a planar saw-tooth knife; the other is a three-dimensional conical saw-tooth knife.

(1)flat saw blade

It consists of two circular blades, the circumference of which is full of sharp serrations. After starting, coffee beans are brought into the blade, instantly cut and crushed into fine particles, fast speed, uniform particles, so commercial large bean grinder almost all used.

(2)Three-dimensional tapered serrated knife

It is composed of two conical irons. The surface of the conical iron is covered with serrations. The friction temperature generated by the conical serration knife is the lowest, and it can also form uniform grinding, that is, the speed is slow, so it is mostly used for household bean grinding machines.