Coffee roasting, what are the taste characteristics of light roasted, medium roasted, and deep roasted coffee beans?

The meaning of baking

1. Definition of Baking

Coffee roasting refers to the process of heating the raw beans to induce a series of physical and chemical reactions inside and outside the beans, generating a variety of coffee flavors such as sour, bitter, and sweet, forming the body and color, and transforming the raw beans into dark brown original beans.

2. The importance of baking

Among the factors that affect the taste of a cup of coffee, green beans account for 60%, roasting accounts for 30%, and extraction accounts for 10%. Good roasting can bring out the personality of green beans to the extreme and minimize the appearance of defective flavors. On the contrary, improper roasting will completely ruin good beans. Since the control of heat, time, and temperature during the roasting process is very difficult to grasp, roasting technology is a very complex technology, so the importance of roasting becomes more prominent.

Roasting degree

From the perspective of roasting degree, the darker the roasting degree, the stronger the bitterness; the lighter the roasting degree, the stronger the sourness. The roasting degree to be chosen depends on the characteristics of the coffee beans themselves. For coffee beans with strong bitterness and light sourness, medium to light roasting degree is generally used.

1. Light roast

The lightest brew has no aroma or concentration, the beans are not yet cooked, and have a green taste of raw beans, which is not suitable for grinding and drinking. It is generally used for testing.

(Photo: Nestle Coffee China)

2. Darker Light Roast (Cinnamon)

Also known as cinnamon roast, it is a common roast with a strong sour taste. The color of the beans is very similar to cinnamon, so it is also called cinnamon roast, and the sour taste is stronger. It is favored by people in the western United States.

3. Lighter Medium Roast (Media)

The color deepens, making it easier to extract the original flavor of the coffee beans, which is mellow, sour and delicious.

4. Medium roast (High)

The coffee taste is stronger and the acidity is lighter. This is the general roasting method of coffee beans. The acidity is neutral and bitter, suitable for coffees such as Blue Mountain and Kilimanjaro. It is loved by people in Japan and Northern Europe.

(Photo: Nestle Coffee China)

5. Darker Medium Roast (City)

Also known as city roast, it has a stronger bitter taste than sour taste, almost no sour taste, and a unique aroma. It is suitable for coffee from Colombia and Brazil and is deeply loved by New Yorkers.

6. Normal baking (Full City)

Also known as full-city roasting, it is suitable for brewing iced coffee. It has no sour taste and is mainly bitter. The bitterness will increase, but high-quality beans will have a sweet taste. It is used for iced coffee and is favored by people in Central and South America.

7. French

French roasting method, slightly black in color, strong bitterness, and oil seepage, which deepens the bitterness and concentration. Used for coffee brewed with steam compressor.

(Photo: Nestle Coffee China)

8. Dark Roast (Italian)

Also known as Italian roasting, the deepest roasting degree, the beans are black and translucent, with oil oozing out of the surface and a strong bitter taste. At this stage, the coffee beans have been severely carbonized, and the taste of one coffee bean from another is already difficult to distinguish. Used for Italian steam-pressurized coffee

Factors that change the color of coffee:

Green coffee beans are light green and turn brown after roasting. The brown color unique to roasting mainly comes from brown pigments produced by oligosaccharides, amino acids, and chlorogenic acid. The so-called brown pigment does not refer to a single color or component, but a general term for many components that make coffee turn different colors.

The color of green beans gradually changes during the roasting process because the total amount of brown pigment and the ratio of its molecular size change. Brown pigment can be classified according to molecular size. Light roasting will mostly produce small molecular pigments. As the roasting degree gets deeper, the total amount of pigment gradually increases, and the proportion of large molecular pigments will also increase.

Most lightly roasted beans contain small pigments with a noticeable yellow color. This is a chemical reaction product in the early stages of roasting. It is a substance produced by the reaction between the thermal decomposition of oligosaccharides and chlorogenic acids.

If you continue to bake, the oligosaccharides will caramelize and produce caramel pigment. When the oligosaccharides react with amino acids to produce molasses pigment (Melanoidin), a slightly larger reddish-brown pigment will occur. The reaction produced by molasses pigment is called Maillard reaction, which is a very important type of food chemistry reaction. The color of toast, miso, soy sauce, etc. are all the result of Maillard reaction.

If baking continues, proteins and polysaccharides are also added, turning the pigment into a dark brown color whose molecules are more than a hundred times larger.

This pigment is actually one of the elements that make up the bitter taste of coffee. It is generally believed that the larger the pigment molecule, the stronger the bitterness of the coffee and the heavier the taste. Therefore, the intensity and taste of the bitterness will change with the degree of roasting of the coffee, which is affected by the changes in these pigments.

What are the taste characteristics of lightly roasted, medium roasted, and dark roasted coffee beans?

Generally, lightly roasted beans have a light and refreshing flavor, and the flavor is very rich, such as floral, fruity, and some tea flavors. Medium roasted beans are more balanced, with both a refreshing flavor and a heavy taste. Deep roasted beans are more about their taste, and their flavors are usually stronger, such as smoke, chocolate, and woody flavors. And they are accompanied by a heavy taste.

The classification of these three roasting methods is only a very rough classification. In fact, many factors such as the origin of the beans, the variety, and the roaster's style will affect the depth of roasting. This answer is also just a general statement. The barista will adjust the roasting curve according to the characteristics of each bean. The flavor will be different if the beans are put into the pot one degree or two seconds later.

Baking process

1. Drying

When the green beans are heated, the water vapor in the beans will evaporate. When the temperature reaches about 135 degrees, the green beans will turn from green to white.

2. Dehydration

As the heating progresses, the green beans turn from green to light yellow. When the temperature reaches about 160 degrees, the aroma of roasted grains will be emitted. With continued heating, the beans turn light brown.

3. First Explosion

After dehydration is completed at about 190 degrees, the cell walls rupture due to internal heat expansion, forming a "first crack". At this time, a series of thermal decomposition reactions will occur inside the beans. Among them, the caramelization reaction will bring sweetness, dark brown and mellowness to the coffee beans. The first crack will last for about one and a half minutes.

4. Second Explosion

As the heating progresses, it enters the "second crack", at which time a more violent reaction will occur inside the beans. A large amount of heat will be released. As the second crack ends, the raw beans have basically turned black, the bean body has expanded to 1.5 times its original size, oil has appeared on the surface, and the weight has decreased to about 12%-20%.

5. Stop

Generally, roasting ends when the temperature reaches 200 degrees one minute after the second crack at the latest. At this time, it will be a darker French or Italian roast. If the temperature exceeds 230 degrees and continues to be heated, the coffee beans may spontaneously combust.

Major roasting machine brands

1. German probat

Old brand, large, medium and small machines, semi-automatic and fully automatic types are all available, with precise design and expensive prices.

2. Japan Fuji-Royal

The products of Japan's Fuji company also have good performance, but the price is also high.

(III) Introduction to Taiwan Yangjia Baking Machine

The coffee roaster of the Pegasus brand of Yangjia Machinery is a classic model that is stable and practical. The cast iron inner pot makes the boiler temperature stable and has good heat concentration, so that the coffee beans are heated evenly. The boilers of Taiwan Yangjia Pegasus machines are all made of cast iron, and the thickness of the boiler wall reaches 12MM, which is rare in Chinese, American and Japanese machines.

The article comes from: Coffee Workshop