The process and stage characteristics of coffee roasting
The process and stage characteristics of coffee roasting
The flavor of coffee not only depends on the variety of coffee, roasting is also a decisive factor. Basically, the roasting of coffee is a kind of high-temperature coking, which completely changes the substances inside the raw beans, produces new compounds, and recombines to form aroma and mellow flavor. This effect will only occur at high temperature. If only low temperature is used, it will not cause decomposition, and no matter how long it is roasted, coffee beans will not be cooked.
I. Baking process
Most people think that baking is nothing, just frying the raw beans with fire. In fact, in the process of coffee processing, roasting is the most difficult step, it is a kind of science, but also an art, so in Europe and the United States, experienced roasters enjoy a highly respected status. Baking can be divided into the following three stages:
1. Drying
In the early stage of baking, the raw 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 a faint smell of grass. The main function of this stage is to remove moisture, which accounts for about half of the baking time, because water is a good heat transfer conductor and helps to bake the internal material of coffee beans. Therefore, although the aim is to remove water, the baker will make good use of the temperature of the water and properly control it so that it will not evaporate too quickly; in general, it is best to control the water to reach the boiling point and turn into steam in 10 minutes. At this time, the internal material is fully cooked, and the water begins to evaporate, rushing out of the outside of the coffee beans.
2. High temperature decomposition
Baked to about 160 degrees Celsius, the water inside the beans will evaporate into gas and begin to rush out of the outside of the coffee beans. At this time, the interior of the raw bean changed from endothermic to exothermic, resulting in the first burst sound. After the bursting sound, it turns to endothermic again, and the pressure inside the coffee bean is extremely high, up to 25 atmospheric pressure. Heat and pressure begin to deconstruct the original tissue to form new compounds that create the taste and taste of coffee; at about 190 degrees Celsius, the transition between endothermic and exothermic occurs again. Of course, high temperature cracking continues to occur, coffee beans from brown to dark brown, gradually entering the stage of re-baking.
3. Cooling
Coffee must be cooled immediately after roasting, quickly stop the pyrolysis at high temperature and lock the flavor. Otherwise, if the high temperature in the beans continues to work, the aromatic substances will be burned. There are two cooling methods: one is air-cooled and the other is water-cooled. The air-cooled type needs a lot of cold air to cool the coffee beans quickly within 5 minutes. In the field of professional baking, large roasters are equipped with a tray with a rotatable driving arm; when the baking 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 pushing arm stirs the coffee beans to cool them. Although the speed of the water-cooled type is slow, it is clean and does not pollute, and it can better retain the aroma of the coffee, so it is used by the selected coffee industry. The water-cooled method is to spray a layer of water mist on the surface of the coffee beans, allowing the temperature to drop rapidly. As the amount of spraying water is very important, it requires precise calculation and control, and will increase the weight of baked beans, which is generally used in large-scale commercial baking.
- Prev
Coffee chain giant Starbucks once again aims at the Chinese market.
Starbucks China-related sources told reporters that Starbucks has been very cautious about opening stores. This strategy is proposed entirely because of market demand, including supply chain and quality control, service and other aspects of Starbucks is ready, all conditions are ripe Starbucks will open a large-scale store, not rash. The move also means that Starbucks will open a new store in China in 18 hours.
- Next
After Kopi Luwak, Elephant shit Coffee is red again-more disgusting than Elephant shit Coffee
The real elephant shit really made me understand the meaning of dung. It is said that this kind of shit-like coffee sells for $18 a cup. Although I haven't drunk it, just looking at the price, we can see that the taste of this coffee is higher than that of ordinary coffee. But in addition to elephant shit coffee, there are many strange coffees in the world. Now the whisper will take an inventory for you.
Related
- Finally stubborn! Tea shop workers are rising to bear the burden of "Don't talk to me" poster
- The Brazilian government will sell IAC coffee experimental farmland and germplasm bank!
- There are no seconds for sale! The Yayoi Yayoi joint name of Xi Cha Cao was bid up by scalpers
- Where does Panama rose summer come from? How did Rose Summer develop?
- What is the concept of 9bar for an espresso machine? How much pressure does it take to make espresso coffee?
- Three major grading standards for raw coffee beans! Detailed explanation of the classification of raw coffee beans in different countries! What do AA and G1 in coffee beans mean?
- Why is milk foaming quickly? Why did the latte defrost just a few minutes after it was made? How to reduce the disintegration of milk coffee foam?
- Coffee Brewing Guide: How to make your coffee flower aroma stronger? How to break out the fragrance of coffee? What is rose summer in coffee?
- Loss of billions! Kenya's customs system fails to block coffee exports
- What are Ethiopia's "flower queen" coffee beans?