The Culture of Coffee Roasting

Ah, the aroma of coffee.....

It is the roasting of the coffee beans that produces that wonderful coffee aroma and taste by causing the green beans to expand, thereby changing in color, taste, aroma, and density. Coffee that is brewed shortly after  the beans are roasted is coffee at the peak of its flavor. ...and that enticing aroma....

 Much of coffee is roasted on a large scale commercially although an increasing number of coffee drinkers roast their coffee at home to maintain more control of the freshness and flavor of their coffee beans.

The most common roasting machines are drum and hot-air, although other types include packed bed, tangential, and centrifugal roasting machines. Roasting machines may operate in either a batch or a continuous mode.

Drum Roasting Machines

Commercial Drum Roasting Machine

Home Drum Roasting Machine

Drum machines have horizontal rotating drums that tumble the green coffee beans in a heated environment. This heat source is natural gas, liquefied petroleum gas (LPG), electricity, or wood. The most common drum roasters use indirectly heated drums with the heat source beneath the drum.

Hot-air home roasting machine

Hot-air commercial roasting machine

 In  hot-air roasting machines the  coffee beans lie on a screen or  perforated plate The machine  forces heated air through the  screen/perforated plate under the  coffee beans with sufficient force to  lift the beans. The beans heat as  they tumble and circulate.

What exactly  is “Degree of Roast” ?

So, long does a coffee bean need to roast?  Can it be too roasted?

How does one know when a coffee bean is “done”? 

Coffee roaster masters use a variety of names such as City Roast or French Roast to identify the various degrees of roast.   Roastmasters often use a recipe to highlight certain flavor characteristics.  A coffee bean’s origin, variety, processing method or desired flavor influence the recipe a roastmaster chooses.

The degree of roast can be determined by eye although this  is not the most accurate method. As beans absorb heat, this color shifts – from yellow to increasingly darker shades of brown.  Beans also darken as they age, however, so color alone may not be the best way to determine level of roast.  Most roasters use color, bean mass temperature, smell, and sound as they monitor the roasting process.

Beans make sounds during the roasting process, as these sounds indicate their internal temperature. Roastrmasters listen for two temperature thresholds, called “cracks.”  At approximately 401-405 degrees F beans make a cracking sound, similar to that of a piece of popcorn popping.  This is referred to as the “first crack,” the beginning of light roasts.  At 435-441 degrees F, coffee beans give a “second crack, the dividing line between medium and dark roasts.

The following are basic levels of roasting coffee beans:

Green Coffee Beans

These green coffee beans are ready to be shipped or roasted and can be stored for up to 2 years.

Yellow-tan Coffee Beans
329 degrees F

These yellow-tan coffee beans are in the drying stage. They have been in the roasting machine for 8 minutes and are not yet ready to be used to brew coffee.

Light Roast Coffee Beans
401 degrees F

These light roast coffee beans are just at the first "crack." They can be used for brewing, but make a very weak “coffee tea.”

City Roast Coffee Beans
428 degrees F

These city roast coffee beans have finished with their first crack and almost ready to begin their final crack.  The coffee brewed from these beans  is very balanced and complex – plain coffee. Great for coffee with no cream or sugar.

Vienna Roast Coffee Beans
437 degrees F

These Vienna roast coffee beans are about 1 minute after the second crack begins.  The resulting coffee is plain, strong coffee - perfect with milk, cream, or any flavoring.

French Roast Coffee Beans
464 degrees F

These French roast coffee beans usually occur 3 minutes after the second crack begins.  The resulting beans are great for espresso.

Impact of Roasting on Caffeine Level

The degree of roast also impacts the amount of caffeine, with the amount of caffeine decreasing as the level of roasting increases:  1.37% for a light roast, 1.31% for a medium roast, and 1.31% for a dark roast. The grind you choose and the method of brewing can also impact the amount of caffeine.

NEXT: Grinding the Beans

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Who Drinks Coffee?

What country do you think consumes the most coffee per person?

Read on - you might be surprised.

Following is the 18 countries that consume the most coffee.

Rank           Countries                  Amount per person
#1                Norway...........................22.5 lbs
#2                Finland............................22.3 lbs.
#3                Denmark.........................21.4 lbs.
#4                Sweden...........................17.2 lbs
#5                Netherlands.....................15.6 lbs
#6                Switzerland......................15.4 lbs.
#7                German...........................12.6 lbs.
#8                Austria............................12.1 lbs.
#9.               Belgium...........................11 lbs.
#10              France.............................8.6 lbs
#11              Italy..................................7 lbs
#12              United States...................6.6 lbs
#13              Canada............................5.3 lbs
#14              Australia..........................4.4 lbs
#15              Japan...............................3 lbs
#16              United Kingdom...............2.6 lbs
#17              New Zealand....................2 lbs
#18              Ireland..............................1.5 lbs



DEFINITION: Pounds of coffee consumed by person per year, 2002

SOURCE: Coffee consumption by country, Global Market Information Database, published by Euromonitor. Retrieved from http://www.NationMaster.com/graph/foo_cof_con-food-coffee-consumption



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The Culture of Decaffeination

Ah….caffeine…. the reason why some folks turn to their coffee every day…. Some folks like their coffee with that “jolt” – others don’t.

What exactly is caffeine? How is that jolt of caffeine removed from coffee?

Caffeine is a mild stimulant found in more than 63 plants, including coffee beans, cocoa beans, kola nuts, and tea leaves. Caffeine is found most often in soda, chocolate, energy drinks, tea, various alertness pills, and, of course, coffee.

Anthropologists believe caffeine use may date back to the Stone Age.

Morning Coffee Francis Boucher 1739

Coffee originated in Ethiopia and was later introduced to Arabia and the rest of the east. Ethiopian nomads discovered coffee when their animals ate the fruits from specific trees and plants and had an energy boost. The nomads tried eating the same seeds and fruits and had an increase in energy.

Coffee has since been linked to religious ceremonies where people involved in the rituals could stay up and pray or worship most of the night. Coffee was introduced to the Europeans in 1573, and 250 years later in 1821, caffeine was first extracted from coffee.

Removing the caffeine “jolt”

Decaffeination uses green coffee beans. There are four methods of decaffeination, based on the substance used to extract the caffeine: (1) Water , (2) Ethyl Acetate, (3) Supercritical or Liquid CO2, and (4) Methylene Chloride.

These 4 methods share the following 4 stages:

· Stage 1: Swelling the beans water or steam to make the caffeine more available to be removed
· Stage 2: Removing the caffeine from the beans
· Stage 3: Steam stripping to remove all solvent residues from the beans (when applied) / regenerating adsorbents (when applied)
· Stage 4: Drying the decaffeinated coffee beans to return to their normal moisture content

Now, let’s look more closely at the 4 methods of decaffeinating green coffee beans.

Method 1 - Water Method: The green coffee beans are immersed in hot water anywhere from 10 minutes to 2 hours to leech out the caffeine. Much of the coffee’s aromatic character can be lost in this process, so workers saturate beans with the water-soluble components of the coffee. The caffeine is subsequently removed from the solution using activated carbon or other absorbents.

Ethyl - Acetate (EA) 

Method 2 - Ethyl - Acetate method: Ethyl - Acetate (EA) occurs in several natural products and contributes to the characteristic aroma of many fruit. EA is also found in varying concentrations in foodstuffs including green and roasted coffee. Because of the impracticality of gathering EA from natural sources, this process uses a synthetic version. The beans are first steamed for 30 minutes then rinsed repeatedly with ethyl acetate for about 10 hours. The solvent is then drained away and the beans steamed for an additional 10 hours to remove residual solvent.

CO2 Process

Method 3- Supercritical Carbon Dioxide and Liquid Carbon Dioxide method: CO2 is a readily available substance of great purity, naturally available in the air we breathe. Under certain conditions CO2 can provide a selective caffeine extraction, leaving most of the other coffee bean components unaltered. Using CO2 in its supercritical state (between its liquid and gaseous state) requires very high pressure – up to 250 atmospheres, necessitating a large-scale production to be economically viable.




Method 4- Methylene Chloride (i.e. Dichloromethane-DCM) method: DCM is circulated through the water soaked beans. The resulting mixture of DCM and caffeine is drained out. This step is repeated several times, until the residual caffeine content is at or below the legal maximum level of 0.1%.



NEXT: Roasting the beans

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The Culture of Coffee Processing

Ever wonder what happens to the beans after they are harvested?


Read on...

After being harvested, the coffee beans must then be processed either by dry-process, wet-process, or a semi-dry method. In the dry-process, the coffee beans dry while they are still in the cherry. This produces a coffee heavy in body - sweet, smooth and complex. Wet-processing is a new method which removes the four layers surrounding the coffee bean, resulting in a coffee that is cleaner, brighter, and fruitier.

Dry Process

The Dry Process is the oldest and the more traditional method of coffee processing in which coffee cherries are cleaned then spread out in the sun to dry on tables or in thin layers on patios. Workers constantly rake and turn the cherries by hand until the pulp dries. During this process the cherries turn brown. It may take up to 4 weeks before the cherries are dried to the optimum moisture content, depending on the weather conditions. Larger plantations sometimes use machine-drying to speed up the process after the coffee has been pre-dried in the sun for a few days.

Coffee Drying Racks

The drying operation is the most important stage of the process, since it affects the final quality of the green coffee. A coffee that has been overdried will become brittle and produce too many broken beans during hulling (broken beans are considered defective beans). Coffee that has not been dried sufficiently will be too moist and prone to rapid deterioration caused by the attack of fungi and bacteria.

Once dried, the fruit is ready for hulling. During the hulling process the fruits are placed in rotating drums containing blades that break the hull, releasing the coffee beans. Next, the beans are sorted according to size, density, color, and shape.

The dry method is used for about 95% of the Arabica coffee produced in Brazil, most of the coffees produced in Ethiopia, Haiti, and Paraguay, as well as for some Arabicas produced in India and Ecuador. Most Robusta beans are processed by this method. The dry method is not practical, however, in rainy regions, where the humidity of the atmosphere is too high, or where it rains frequently during harvesting. 


Wet Process


In the wet process, the coffee cherries are immersed in water to remove the over ripe or 

Wet Process

under ripe fruit. Bad or unripe fruit will float, and the good fruit sinks. Next the skin of the cherry - and some of the pulp - is removed by pressing the fruit – in water – through a screen. The remaining bean will still have a lot of pulp that needs to be removed. Fermentation is used to separate the coffee bean from the pulp. In machine-assisted wet processing, the machine scrubs off the pulp. After soaking in water for several days, the resulting pulp is removed, and the beans are then sun-dried on cement or mahogany patios for up to 6 weeks. Workers continue to rake the coffee during the day and move the beans into covered buildings during the night until the beans have dried thoroughly.

Semi-dry process

In this third process the coffee cherry passes through a wet screen and is then sun-dried without going through fermentation or through scrubbing.


Grading and Sorting the Beans

Machine sorting

After the beans have dried they are sorted and graded, either by machine or by hand. Coffee beans may be polished to remove any remaining chaff.

Coffee Sacks

After sorting and grading, beans are bagged and stored, waiting for the next stage of their journey.  








NEXT: Decaffeinating the Coffee Beans


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The Culture of Coffee Harvesting

Coffee is harvested when the coffee cherries are bright red, glossy, and firm.  Coffee cherries can be harvested in three different ways: (1) hand-harvesting, (2) machine-harvesting, or (3) stripped from the coffee tree with both unripe and overripe cherries.  

Hand-Harvesting

Hand-harvesting coffee in Bolivia

Hand-harvesting allows farmers to harvest one coffee tree repeatedly as beans are harvested one at a time.  Each coffee cherry is carefully removed without disturbing the remaining unripe fruit on the branch. Under-ripe as well as over ripe fruit can impact the taste of the coffee.  Hand-picking allows the under ripe fruit to remain on the tree for picking later in the season.

Some estimates suggest coffee pickers can pick between 100 and 200 pounds of coffee cherries each day.  Only 20% of that weight, however, is the actual coffee bean.  Hand-harvesting is more expensive than other methods because it is labor-intensive and is used primarily with Arabica beans which are grown in mountain plantations.

Coffee Shaker Fingers

Mechanical Harvesting

Mechanical harvesting uses a flexible wide-tooth comb as a rake to pick the coffee fruit from the branches. In the shaker method, a machine shakes the trunk, making the ripe fruit    fall off of the branches.

Stripping Method

The stripping method uses one stroke to harvest all coffee fruits on the branch , despite their stage of development - green, yellow, red, or black. Leaves and other matter often fall off with the fruits. Branches can be stripped either by hand or by machine, but in either case, the coffee cherries are stripped from the branch at the same time, resulting in only one harvest per season.

NEXT: Processing the Coffee Beans

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The Culture of Growing Coffee

Coffee is grown in more than 50 countries worldwide, with 30 of those countries producing more than 5 million tons of coffee each year.  Many of these countries rely on coffee production for their economic success.  The  top 10 coffee producing countries are (1) Brazil, (2) Vietnam, (3) Colombia, (4) Indonesia, (5) Mexico, (6) India, (7) Ethiopia, (8) Guatemala, (9) Honduras, and (10) Peru.

Americans consume more than 1/3 of the total coffee grown throughout the world.

Hawaii is the only US location that produces coffee.


Although more 60 varieties of coffee grow throughout the world, only two are commercially cultivated: Arabica and Robusta.

Arabica blossom

Did you know that coffee is a fruit that grows on a coffee tree?  


Coffee plants produce delicate white blossoms  that last for approximately a day.  

Arabica"cherry"

By the time this blossom appears, however, that tree has been growing for anywhere from 3 to 5 years.   After  fertilization, these blossoms  become coffee “cherries.”   These cherries are often hand-picked as only the ripest, the reddest cherries are picked at a time, allowing multiple harvesting of the same plant.   


Inside each cherry is the coffee bean – that from which coffee is made.

The ripe coffee cherry is covered with a thick red, yellow, or brown skin that surrounds  the pulp.   The coffee bean is found under this pulp, covered by the parchment, another protective layer. The beans are covered by yet another layer – the silver skin. Harvesting a coffee bean requires that the pulp, parchment, and silver skin be removed. 

 The Sun versus Shade Debate

Coffee originally was grown in the shade of trees,   to protect the leaves from burning, but over the past 30 years, new sun-tolerant coffee varieties have been developed.  USAID and other international developmental agencies have encouraged coffee farmers to convert their  shade grown coffee practices to sun-grown systems.  While sun-grown coffee produces substantially increased yields,  this method of coffee farming requires the use of chemical fertilizers in addition to  insecticides, herbicides, and fungicides. Coffee trees grown on sun plantations tend to lack tree root structures, often resulting in increased erosion and toxic run-off. 


Because more sun coffee trees can be cultivated per acre as opposed to shade varieties, and each sun-grown coffee tree produces as much as three times the amount of coffee as that of shade-grown coffee trees, coffee farms have started to shift away from shade-grown coffee to sun-grown coffee. Sun-grown farms, however, have been linked to serious environmental side effects. Coffee cherries from sun-grown coffee trees are also smaller than those from shade-grown coffee trees. 


The traditional shade-grown coffee farm resembles a forest. This forest has several layers of trees (including fruit trees and hardwoods), plants that grow in the tops of trees (such as orchids), and  other bushes and plants. Often as many as 40 different species of trees are found in the traditional shade coffee plantation, protecting the coffee plants from the scorching sun, rain, and wind, and reducing the need for weeding and pest control. As in any forest, organic matter builds up, creating a natural mulch layer. This forest also supports a variety of wildlife.  This environment differs greatly from the sun-grown field that resembles a corn field with only one species of plant.

Shade-grown coffee plantation

Sun-grown coffee plantation

Coffee plantations vary from the traditional, very complex forest environment with many varieties of plants to what is called a monoculture - one type of plant only.... and everything between. Traditional mountain-grown shade coffee is a more complex system where coffee plants replace the shrub-like forest plants while maintaining the original forest canopy. In a monoculture, the coffee plants grow in direct sunlight with no tree cover.  This lack of tree cover necessitates high volumes of chemical fertilizers and pesticides, uses of machinery, and an intensive year-round workforce.  Monoculture also creates the largest coffee yield per acre. this use of chemicals and pesticides requires that fields be allowed to lay fallow while shade-grown coffee plantations can produce year after year. 


NEXT: Harvesting the coffee

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