Roasters buy raw green coffee beans in bulk and roast them using professional roasting equipment. Home-Roasters buy green coffee and roast it using cheap roaster DIY machines which are very easy to build and use. These include woks, corn poppers, heatguns, convection ovens (turbo crazy), barbecue drums and so on. If you’re interested in green coffee beans check out the varieties offered at The Fresh Coffee Shop!

Buying Green Coffee Beans

Green coffee beans can have "defects" which can harm the result in the coffee cup.  You can tell a great deal about the processing conditions of a coffee by looking at the appearance of the green coffee, touching it and smelling it.  Although cupping is the definitive way to check for problems, the green coffee appearance is a good prognostic tool.

1.  The green beans should be of nearly equal size, be similarly shaped, and have a similar color.  The more even the coffee the more easy and even the roasting process.  Very uneven coloring hints toward drying problems, whereas uneven shapes may indicate a mixing of different coffees and qualities...

1.  Washed Arabica coffees should be even and bright.  The green coffee beans should not have an uneven or dull color.  If they do, it is likely have been dried or processed incorrectly.  If the green beans look faded, the cup quality will be faded.

2. Improper drying on patios or in mechanical dryers can usually be observed visually.  Rapid drying in mechanical dryers results in dull or brown coffees.  Beans that are mottled (or quakers when roasted) result when the coffee is dried too quickly, spread too thin on the patios, or not rotated as frequently as recommended. If the temperature used on the dryers is over 42°C you can expect a dull or baked cup.

3.  If coffee pulp is present in the tanks during processing it can result in brownish tinges on the green beans.  This is also indicative of harvesting over-ripe cherries.

4.  Natural (dry) processed coffees will often be covered in brown silverskin which has attached itself to the bean.  In Brazil they call this a fox bean and it is not considered a defect.  Novice classifiers might expect this type of bean to be a defect, but if you can remove a portion of the silver-skin by rubbing on the black sorting mat it is not considered a defect.  Green (under ripe) coffee also has a silver-skin attached to it, but this cannot be removed by simple rubbing.  In a washed coffee, fox beans may indicate sour, fruity, or Rio tastes.  This should be confirmed in the cup and not visually.

5.  Do the coffee beans have a little pink skin covering them or inside the crack of the bean?  In some areas this is a serious defect which most people do not consider to be a defect.  Since it is not a part of the green coffee classification, these beans could be passed on to the buyer as specialty grade.  These beans should be separated and cupped to determine if the defect is serious.

6.  If the coffee beans are whitish or faded around the edges then  this is likely a result of insufficient drying or storage in humid conditions.  The cup will be bland and ordinary.  These white marks are also observed in coffee that has not been dried evenly.  The part of the bean that has a whitish tone has higher moisture than the other parts of the bean.  Whitish or discolored beans can also result from oxidation, contact with the earth, or polluted waters.

7. Smell the green coffee beans. Ferment and smoke damage can be easily detected at this point, whereas they might be more subtle when roasted.

8. Pick up the green beans. How do they feel? If they feel glass-like and fragile they have been over dried or dried at too high of a temperature. If they are pliable they have not been dried sufficiently and should be rejected since mold growth at this point is unavoidable.

Processing and Flavor Characteristics of Coffee

Dry-Process: The dry-process produces coffee that is heavier in body, sweet, fruity, and complex.  The dry-process is often used in countries where rainfall is scarce and long periods of sunshine are available to dry the coffee properly.  Most coffees from Indonesia, Ethiopia, Brazil, and Yemen are dry-processed. It is more risky than the washed method and off-tastes may result in the cup.

Wet-Process: Wet-processing results in a coffee that is lighter in body, cleaner, and brighter.  Most countries with coffee valued for its perceived acidity, will process their coffee using the wet-process, like Costa Rica and Kenya.

Pulped Natural: The pulped natural method consists of pulping a coffee, but emitting the fermentation stage to remove the silverskin.  This results in a beverage that has characteristics of both a dry- and wet-processed coffee.  It is often sweeter than wet-process, has the body of a dry-processed, but also retains some of the acidity of a wet-processed coffee.  This type of processing can only occur in countries where the humidity is low and the silverskin can be dried rapidly without fermenting.  Brazil has made this method famous and produces some of the best pulped natural coffees in the world. A hybrid method is also used in Sumatra.

Where to Buy Green Coffee Beans

If you’re interested in high quality fresh green coffee beans at fantastic prices check out the varieties offered at The Fresh Coffee Shop!

Don't forget to check out our special special deals!

After the raw coffee fruit (cherry) gets collected the processing of coffee converts it to the commodity green coffee. The cherry has the fruit or pulp removed leaving the seed or bean which is then dried. The coffee processing method used varies and can have a significant effect on the flavor of roasted and brewed coffee.

Coffee Processing Methods

Wet Process

The wet process is the most commonly used coffee processing method, especially among premium coffees. After the green coffee is picked the coffee is sorted by immersion in water. Bad or unripe fruit will float and the good ripe fruit will sink. The skin of the cherry and some of the pulp is removed by pressing the fruit by machine in water through a screen. The bean will still have a significant amount of the pulp clinging to it that needs to be removed.

In the ferment and wash method of wet processing the remainder of the pulp is removed by breaking down the cellulose by fermenting the beans with microbes for several days and then washing them with large amounts of water. Fermentation can be done with extra water or in “Dry Fermentation” in the fruits own juices only.

In machine-assisted wet processing, fermentation is not used but a machine scrubs off the coffee pulp. After the pulp has been removed what is left is the bean surrounded by two additional layers, the silver skin and the parchment. The beans must be dried to a water content of about 10% before they are stable. Coffee beans can be dried in the sun or by machine but in most cases it is dried in the sun to 12-13% moisture and brought down to 10% by machine. Drying entirely by machine is normally only done where space is at a premium or the humidity is too high for the beans to dry before mildewing. When dried in the sun coffee is most often spread out in rows on large patios where it needs to be raked every six hours to promote even drying and prevent the growth of mildew. Some coffee is dried on large raised tables where the coffee is turned by hand. Drying coffee this way has the advantage of allowing air to circulate better around the beans promoting more even drying but increases cost and labor significantly. The parchment is removed from the bean and what remains is green coffee.

Dry Process

Dry process is also known as unwashed or natural method and it is the oldest method of processing coffee. The entire cherry after harvest is placed in the sun to dry on tables on in thin layers on patios. It takes between ten days and two weeks for the cherries to completely dry. The cherries need to be raked regularly to prevent mildew while they dry. Once dry the skin, pulp and parchment are removed from the bean. While coffee was once all dry processed it is now limited to regions where water or infrastructure for machinery is scarce. The supply of dry processed coffee is very limited with coffee from the Harrar region of Ethiopia and some areas of Yemen and Brazil being the primary sources.

Semi Dry Process

Semi Dry is a hybrid process in very limited use in Brazil, Sumatara and Sulawesi. The cherry is passed through a screen to remove the skin and some of the pulp like in the wet process but result is dried in the sun and not fermented or scrubbed.

Additional processing steps

Sorting Grading

Once the coffee is dried to green coffee it is sorted by hand or machine to remove debris and bad or misshapen beans. The coffee is also often sorted by size and placed into one of several grades, like AB, AA.

Polishing

Some coffee beans are polished to remove the silver skin. This is done to improve the green coffee beans appearance and eliminate a byproduct of roasting called chaff. It is considered by some people to have detrimental results to the taste by raising the temperature of the bean through friction which changes the chemical makeup of the bean.

Green coffee stored in bags

Green coffee is fairly stable if it is stored correctly. It must be placed in containers that can breath usually some type of fiber sack and kept dry and clean.

Aging

All coffee, when it was introduced in Europe, came from the port of Mocha in what is now modern day Yemen. To import the beans to Europe the coffee was on boats for a long sea voyage around the Horn of Africa. This long journey and the exposure to the sea air changed the coffee flavor. Later coffee spread to India and Indonesia but still required a long sea voyage. Once the Suez Canal was opened the trip to Europe was greatly reduced and coffee that had not change during a long sea voyage started arriving. In some part this fresher coffee was rejected as they had developed a taste for the changes that were brought on by a long sea voyage. To meet the need some coffee was aged by keeping in large open sided warehouse at the port for six or more months to simulate the effects of a long sea voyage before it was shipped to Europe.

Decaffeination

Decaffeination is the process of extracting caffeine from green coffee beans prior to roasting. The most common decaffeination process used in the United States is supercritical carbon dioxide (CO₂) extraction. In this process, moistened green coffee beans are contacted with large quantities of supercritical CO₂ (CO₂ maintained at a pressure of about 4,000 pounds force per square inch (28 MPa) and temperatures between 90 and 100 °C [194 and 212 °F]), which removes about 97 % of the caffeine from the beans. The caffeine is then recovered from the CO₂, typically using an activated carbon adsorption system.

Another commonly used method is solvent extraction, typically using oil (extracted from roasted coffee) or ethyl acetate as a solvent. In this process, solvent is added to moistened green coffee beans to extract most of the caffeine from the beans. After the beans are removed from the solvent, they are steam-stripped to remove any residual solvent. The caffeine is then recovered from the solvent, and the solvent is re-used. Swiss Water extraction is also used for decaffeination. Decaffeinated coffeebeans have a residual caffeine content of about 0.1 % on a dry basis.

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Processing of coffee".

Coffee processing methods as we saw vary. Each coffee processing method creates a different taste result. You can find more relevant information in the articles of the FreshCoffeeShop website. You can also find information about the taste and the roasting guidelines for green coffee beans of the various coffee producing regions of the world.

The coffee plant of Coffea Arabica, can be cultivated in the geographic zone, between the Tropics of Cancer and Capricorn.

There are three main coffee growing regions in the world.

• Latin America:
  • Central
  • South
• Africa
• Asia-Indonesia

A special coffee growing region is Yemen in Arabian Peninsula. One of the most infamous coffees is Jamaica Blue Mountain. The top coffee producing countries are Brazil and Colombia in Latin America.

Central L. America

Central American coffees are generally light-bodied and relatively high acidity. Some examples include:

• Costa Rica
• Guatemala (more body than the rest)
• Honduras
• Jamaican Blue Mountain
• Mexico
• Nicaragua

South America

South American countries tend to have slightly heavier bodies than Central American coffees, somewhat less acidity, and more balanced overall taste. Some examples include:

• Colombia
• Brazil
• Bolivia

Africa

The origin of all coffees, Africa has unique coffee with sweet, fruity, spicy, and exotic flavors. Usually high acidity especially for washed coffees like Kenya's. Some examples include:

• Ethiopia
• Kenya
• Uganda

Arabian Peninsula - Yemen

In Arabian Peninsula we find the famous Mocha from Yemen. Yemen Mocha has a very distinct flavor, which sets it apart from other coffee. Yemen Mocha coffees aroma is frequently to chocolate or wine. Examples include:

• Sanani
• Ismaiili
• Mattari
• Hazari

Asia-Indonesia

Indonesian coffee has a long finish, full body, full flavor, and low acidity. Earthy flavors, with exotic aromas of spices, cheese, mushrooms, herbs etc. Some examples include:

• Sumatra
• Sulawesi (former name Celebes)
• Timor
• India

Acidity

The perceived acidity of coffee results from the proton donation of acids to receptors on the human tongue. Acidity is typically a highly valued quality especially in Central American and some East African coffees. Sourness, however, is an extreme of acidity and can be considered a defect. Acidity has been correlated with coffees grown at very high altitudes and in mineral rich volcanic soils. The perceived acidity of washed coffees is also significantly higher than the acidity found in naturally (dry) processed coffees. This is likely due to an increase in the body of naturally processed coffees relative to wet processed coffees since body masks a coffee's acidity. The acid content in a brew is also greatly dependent upon the roast degree, type of roaster, and brewing method.

The pH of a coffee has been found to correlate with the perceived acidity of a coffee by Pangborn, Sivetz and Desrosier, and Griffin and Blauch; whereas Voilley et al. suggests that titratable acidity produces a better correlation to perceived acidity.

The acids found in roasted coffee may be classified into three groups: aliphatic, chlorogenic, and alicyclic carboxylic and phenolic acids

Aroma

The aroma of a coffee is responsible for all flavor attributes other than the mouthfeel and sweet, salt, bitter, and sour taste attributes that are perceived by the tongue. Therefore, it might be said that the aroma is the most important attribute to specialty coffee, as it constitutes the biggest factor affecting taste. Even instant coffee has the components responsible for stimulation of our taste buds. The difference, however, is that instant coffee lacks most of the aromatic volatile compounds causing a dramatic decrease in the overall flavor.

Aroma is perceived by two different mechanisms. It can either be sensed nasally via smelling the coffee through the nose or retronasally. Retronasal perception occurs when the coffee is either present in the mouth or has been swallowed and aromatic volatile compounds drift upward into the nasal passage.

The number of aromatic compounds found in coffee increases every year. Today, the number is well over 800 and as our analytical methods become more precise more will be uncovered. Yet, the perception of aroma is dependent upon both the concentration of the compound and its odor threshold. With that said, understanding coffee aroma is not as difficult as understanding how over 800 compounds interact with the olfactory epithelium. It is probable that a relatively small group of compounds that share both a high concentration and a low odor threshold make up the fragrance we know as coffee aroma. This article will discuss the recent research that has narrowed in on these aroma impact compounds.

Body

Body is the weight of the coffee that can best be sensed by allowing the coffee to rest on the tongue and by rubbing the tongue against the roof of the mouth.  Body ranges from thin, to light, to heavy and is a result of the fat content.  The viscosity, however, results from proteins and fibers in the brew.  Medium and dark roast styles will have a heavier body than lighter roasted coffees, but conversely will have less acidity.