Unroasted beans contain similar if

Unroasted beans contain similar if not higher levels of acids, protein, sugars, and caffeine as those that have been roasted, but lack the taste of roasted coffee beans due to the Maillard and other chemical reactions that occur during roasting.

The vast majority of coffee is roasted commercially on a large scale, but small-scale commercial roasting has grown significantly with the trend toward "single-origin" coffees served at specialty shops. Some coffee drinkers even roast coffee at home as a hobby in order to both experiment with the flavor profile of the beans and ensure themselves of the freshest possible roast.

Process
The coffee-roasting process follows coffee processing and precedes coffee brewing. It consists essentially of sorting, roasting, cooling, and packaging but can also include grinding in larger-scale roasting houses. In larger operations, bags of green coffee beans are hand- or machine-opened, dumped into a hopper, and screened to remove debris. The green beans are then weighed and transferred by belt or pneumatic conveyor to storage hoppers. From the storage hoppers, the green beans are conveyed to the roaster. Initially, the process is endothermic (absorbing heat), but at around 175 °C (347 °F) it becomesexothermic (giving off heat).

For the roaster, this means that the beans are heating themselves and an adjustment of the roaster's heat source might be required. At the end of the roasting cycle, the roasted beans are dumped from the roasting chamber and cooled with uncompressed forced air.

In Vietnam coffee is often coated with oil (traditionally clarified butter) and a small amount of sugar prior to roasting to produce a "butter roast". The roasting process results in an additional caramelized coating on the beans.


Equipment

The most common roasting machines are of two basic types: drum and hot-air, although there are others including packed-bed, tangential and centrifugal roasters. Roasters can operate in either batch or continuous modes. Home roasters are also available.

Drum machines consist of horizontal rotating drums that tumble the green coffee beans in a heated environment. The heat source can be supplied by natural gas,liquefied petroleum gas (LPG), electricity, or even wood. The most common employ indirectly heated drums where the heat source is under the drum. Direct-fired roasters are roasters in which a flame contacts the beans inside the drum; very few of these machines are still in operation.

Hot-air roasters force heated air through a screen or perforated plate under the coffee beans with sufficient force to lift the beans. Heat is transferred to the beans as they tumble and circulate within this fluidized bed.


Roasts
Some coffee roasters use names for the various degrees of roast, such as City Roast and French Roast, for the internal bean temperatures found during roasting. Roastmasters often prefer to follow a recipe known as a "roast profile" to highlight certain flavor characteristics. Any number of factors may help a person determine the best profile to use, such as the coffee's origin, variety, processing method, or desired flavor characteristics. A roast profile can be presented as a graph showing time on one axis and temperature on the other, which can be recorded manually or using computer software and data loggers linked to temperature probes inside various parts of the roaster.
The most popular, but probably the least accurate, method of determining the degree of roast is to judge the bean's color by eye (the exception to this is using a spectrophotometer to measure the ground coffee reflectance under infrared light and comparing it to standards such as the Agtron scale). As the coffee absorbs heat, the color shifts to yellow and then to increasingly darker shades of brown. During the later stages of roasting, oils appear on the surface of the bean. The roast will continue to darken until it is removed from the heat source. Coffee also darkens as it ages, making color alone a poor roast determinant. Most roasters use a combination of temperature, smell, color, and sound to monitor the roasting process.

Sound is a good indicator of temperature during roasting. There are two temperature thresholds called "cracks" that roasters listen for.

At approximately 196 °C (385 °F), the coffee will emit a cracking sound. This point is referred to as "first crack," marking the beginnings of a "light roast".

At first crack, a large amount of the coffee's moisture has been evaporated and the beans will increase in size.

When the coffee reaches approximately 224 °C (435 °F), it emits a "second crack", this sound represents the structure of the coffee starting to collapse. If the roast is allowed to progress further, the coffee will soon fully carbonize, and eventually combust.

These images depict samples taken from the same batch of a typical Brazilian green coffee at various bean temperatures with their subjective roast names and descriptions.


Unroasted

Kết quả (Việt) 1:

Unroasted đậu chứa tương tự nếu không cao hơn mức độ của các axit, protein, đường và caffeine như những người đã được rang, nhưng thiếu các hương vị của rang hạt cà phê do Maillard và các phản ứng hóa học xảy ra trong quá trình rang.Đại đa số cà phê được rang thương mại trên một quy mô lớn, nhưng quy mô nhỏ thương mại rang đã phát triển đáng kể với các xu hướng về hướng "đơn nguồn gốc" cà phê được phục vụ tại các cửa hàng đặc sản. Một số người uống cà phê thậm chí rang cà phê tại nhà như là một sở thích để cả hai thử nghiệm với các hồ sơ hương vị của hạt cà phê và đảm bảo rằng mình có thể nướng tươi mới.Quá trìnhQuá trình rang cà phê sau chế biến cà phê và cà phê pha cà phê, đến trước. Nó bao gồm cơ bản phân loại, rang, làm mát, và bao bì nhưng cũng có thể bao gồm mài trong ngôi nhà rang quy mô lớn hơn. Trong các hoạt động lớn hơn, thị trấn này có túi của hạt cà phê xanh là tay hay máy-mở, đổ vào một phễu, và kiểm tra để loại bỏ các mảnh vụn. Đậu xanh sau đó nặng và chuyển bằng đai hoặc băng tải khí nén cho lí rầy. Từ lí rầy, đậu xanh được chuyển tải đến máy sấy. Ban đầu, quá trình này là thu nhiệt (hấp thụ nhiệt), nhưng tại khoảng 175 ° C (347 ° F) nó becomesexothermic (cho giảm nhiệt).Máy sấy, điều này có nghĩa rằng những hạt cà phê sưởi ấm mình và điều chỉnh nguồn của máy sấy nhiệt có thể được yêu cầu. Vào cuối của chu kỳ rang cà phê, hạt cà phê rang đổ từ trong buồng rang và làm mát bằng khí nén ép.In Vietnam coffee is often coated with oil (traditionally clarified butter) and a small amount of sugar prior to roasting to produce a "butter roast". The roasting process results in an additional caramelized coating on the beans.Equipment The most common roasting machines are of two basic types: drum and hot-air, although there are others including packed-bed, tangential and centrifugal roasters. Roasters can operate in either batch or continuous modes. Home roasters are also available.Drum machines consist of horizontal rotating drums that tumble the green coffee beans in a heated environment. The heat source can be supplied by natural gas,liquefied petroleum gas (LPG), electricity, or even wood. The most common employ indirectly heated drums where the heat source is under the drum. Direct-fired roasters are roasters in which a flame contacts the beans inside the drum; very few of these machines are still in operation.Hot-air roasters force heated air through a screen or perforated plate under the coffee beans with sufficient force to lift the beans. Heat is transferred to the beans as they tumble and circulate within this fluidized bed.RoastsSome coffee roasters use names for the various degrees of roast, such as City Roast and French Roast, for the internal bean temperatures found during roasting. Roastmasters often prefer to follow a recipe known as a "roast profile" to highlight certain flavor characteristics. Any number of factors may help a person determine the best profile to use, such as the coffee's origin, variety, processing method, or desired flavor characteristics. A roast profile can be presented as a graph showing time on one axis and temperature on the other, which can be recorded manually or using computer software and data loggers linked to temperature probes inside various parts of the roaster.The most popular, but probably the least accurate, method of determining the degree of roast is to judge the bean's color by eye (the exception to this is using a spectrophotometer to measure the ground coffee reflectance under infrared light and comparing it to standards such as the Agtron scale). As the coffee absorbs heat, the color shifts to yellow and then to increasingly darker shades of brown. During the later stages of roasting, oils appear on the surface of the bean. The roast will continue to darken until it is removed from the heat source. Coffee also darkens as it ages, making color alone a poor roast determinant. Most roasters use a combination of temperature, smell, color, and sound to monitor the roasting process.
Sound is a good indicator of temperature during roasting. There are two temperature thresholds called "cracks" that roasters listen for.

At approximately 196 °C (385 °F), the coffee will emit a cracking sound. This point is referred to as "first crack," marking the beginnings of a "light roast".

At first crack, a large amount of the coffee's moisture has been evaporated and the beans will increase in size.

When the coffee reaches approximately 224 °C (435 °F), it emits a "second crack", this sound represents the structure of the coffee starting to collapse. If the roast is allowed to progress further, the coffee will soon fully carbonize, and eventually combust.

These images depict samples taken from the same batch of a typical Brazilian green coffee at various bean temperatures with their subjective roast names and descriptions.


Unroasted