Raw coffee beans themselves have no coffee flavor, and only after frying can they smell rich coffee flavor. Therefore, the roasting of coffee beans is the transformation process of the internal components of coffee beans. Only after roasting can you smell the aroma of coffee. Let me tell you something about coffee roasting. Let's have a look.
Definition of baking
The so-called coffee roasting refers to the process of heating raw beans to promote a series of physical and chemical reactions inside and outside coffee beans, and in this process, coffee with sour, bitter and sweet flavors is produced, which forms alcohol and color tone, and turns raw beans into dark brown raw beans.
Among the factors affecting the taste of a cup of coffee, raw beans account for 60%, baking accounts for 30%, and extraction accounts for 10%. Good baking can maximize the personality of raw beans and minimize the appearance of taste defects, otherwise improper baking will completely destroy good beans. Because the control of heat, time and temperature in baking process is very difficult to grasp, and baking technology is a very complicated technology, so the importance of baking is more prominent.
Characteristics and types of baking machines
There are three common bread makers, namely, hot air type, direct fire type and semi-direct fire and semi-hot air type. Next, I will introduce the characteristics of the three models for you.
1. Hot air type:
The hot air roaster sucks in air with a blower, then lets the air pass through a heating coil to raise its temperature, and uses hot air as a heating source to roast coffee beans. Hot air can not only provide the temperature needed for baking, but also use the power of airflow to stir coffee beans, killing two birds with one stone. Now there are also professional hot air roasters on the market, which combine the electric tumbling roasting chamber with the heat flow to make the coffee beans heated more evenly during roasting.
Advantages: high thermal efficiency, fast heating speed, uniform heating of raw beans and easy control.
Disadvantages: Because of the high heating efficiency, it is easy to cause the temperature to rise too fast, leading to the growth of beans. Core? Is the so-called sandwich, the temperature rises too high, and it is easy to make the caramelization reaction of coffee insufficient!
Taste characteristics: the sour taste is obvious, and the taste is clean and simple, but the taste is not rich enough and lacks depth, and deep baking is easy to produce pungent smell.
2. Direct type:
As the name implies, direct fire is to directly heat coffee beans with flame, which has evolved to this day. Fire? In addition to the general flame (including gas stove fire and charcoal fire), it also includes infrared rays and electric heating tubes.
Advantages: longer baking time, more complete caramelization reaction and richer taste.
Disadvantages: it is easy to cause uneven baking. If the heat is not well controlled, it is easy to scorch the coffee beans and form bitter taste. Taste characteristics: Bitter and sour aroma is deeper than hot air, with higher alcohol content and smooth taste, but the dry aroma of coffee beans is weak, and sometimes when lightly roasted, the taste of coffee beans will produce strong grass flavor.
3. Semi-direct fire and semi-hot air type:
The baking method, which combines the advantages of direct fire and hot air, is the mainstream of commercial coffee machines at present. Semi-direct fire semi-hot air baking is actually similar to direct fire baking, except that there are no holes in the outer wall of the baking container, so the flame will not directly contact the coffee beans; In addition, it is necessary to increase ventilation and exhaust equipment to introduce hot air outside the baking container into the baking room to improve the baking efficiency. Another function of this ventilation device is to suck out the fallen silver skin of coffee beans and prevent the silver skin from burning in the baking room due to high temperature, which will affect the taste of coffee beans.
This kind of baking machine has both advantages and disadvantages of hot air and direct fire, and its heating mode can be changed by adjusting the speed of hot air and baking room. The bigger the hot air is, the faster the speed is, and the closer it is to the hot air type, and vice versa.
Taste characteristics: The overall taste of coffee beans is rich, the alcohol content is high, and the dry aroma is far from the wet aroma, which is excellent for the characteristics of coffee origin.
Baking stage
1. When drying and heating raw beans, the water vapor in raw beans will evaporate, and when the temperature is around 135 degrees, raw beans will turn from green to white.
2. Dehydration: When heated, raw beans change from green to light yellow. When the temperature is as high as 160 degrees, it will give off the smell of grass or the smell of roasted grain. If heating is continued, the beans will turn light brown.
3. Once exploded, the cell wall will burst due to internal thermal expansion after dehydration at 190 degrees. At this time, a series of thermal decomposition reactions will not occur in the coffee beans, but caramelization reaction will bring sweetness, dark brown and alcoholicity to the coffee beans, and the explosion will last for about one minute.
4. Secondary explosion, with the progress of heating, enters the secondary explosion, and at this time, a more intense reaction will occur inside the beans, releasing a lot of heat. With the end of the second explosion, the raw beans have basically turned black, the bean body has expanded to about 1.5 times of the original, the surface is oily, and the weight has decreased by about 12%-20%.
5. Stop baking, usually about one minute after the second explosion. When the temperature reaches 230, it will be French or Italian deep baking. If the temperature is higher than 230, coffee beans may burn naturally.
Baking degree
1, lightly baked:
Baking degree; Very shallow baking, also known as shallow baking.
When the roasting degree is the lightest in all roasting stages, the surface of coffee beans is faint cinnamon color, and the taste and aroma are insufficient, so it is almost inedible. Generally used for inspection, rarely used for tasting.
2. Cinnamon roll:
Baking degree; Light roast, also called cinnamon roast.
Generally, the roasting degree is cinnamon in appearance, which has removed the smelly green taste, has a fair aroma and strong acidity, and is a commonly used roasting degree of American coffee.
3. Medium roast:
Baking degree; Moderate baking, also called micro-baking.
The baking temperature is moderate and light, belonging to the United States. In addition to sour taste, bitter taste also appeared, and the taste was good. The aroma, acidity and alcohol content are moderate, and it is often used to bake mixed coffee.
4.HIGHRoast:
Baking degree; Moderate deep baking, also known as concentration baking.
It belongs to medium deep baking, slightly stronger than medium baking, with a little strong tea color on the surface and strong bitterness. Coffee tastes sour and bitter, with good aroma and flavor, and is most often loved by people in Japan and Central Europe. (Blue Mountain Coffee)
5. city barbecue:
Baking degree; Medium and deep baking, also known as city baking.
The most standard baking degree, bitter and sour balance, is often used in French coffee. (Brazil, Colombia)
6. BBQ all over the city:
Baking degree; Slight deep baking, also known as deep city baking.
It is slightly stronger than the medium-deep baking degree, the color becomes quite deep, and the bitterness is stronger than the sour taste. It belongs to the baking method in Central and South America and is very suitable for making all kinds of iced coffee.
7. French barbecue:
Baking degree; Deep baking is also called French baking.
Also known as French or European baking, it belongs to deep baking, with strong tea flavor, black color and no sour taste. It is the most popular in Europe, especially in France, because the fat has penetrated into the surface and has a unique flavor, which is very suitable for Leo coffee and Vienna coffee.
8. roaming in Italy:
Baking degree; Extreme deep baking, also known as Italian baking.
Also known as Italian baking, the baking degree is charred before carbonization, which is mainly popular in Latin countries and suitable for fast coffee and cappuccino. Mostly used in Espresso series coffee.
;