Revised: September 27, 2015
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About Coffee: Home Coffee Roasting

Home Coffee Roasting

Choosing Green Beans
Every green coffee holds in its vegetable heart a slightly different collection of secrets. One of the pleasures of roasting at home is becoming acquainted with those intimacies in a far more direct and active way than by simply tasting someone else's roasted coffees.

Green Coffee Basics

The world's coffees are many and their differences complex. What follows is a very general orientation to selecting green coffees from the point of view of the home roaster. Keep in mind that the ultimate test of a coffee is not its name, or its grade, or any of the rest of the muttering that we attach to things, but rather its taste. If you try it and like it, then it's a good coffee, no matter what I say. And if you don't like it, then you should be prepared to ignore all of the pontificating that tries to convince you otherwise.

Narrowing the Field: Species

Botanists now recognize approximately one hundred species of coffee plant, but only one, Coffea arabica, is the source of all of the world's most celebrated coffees.

The coffee species second in importance is Coffea robusta, or Coffea canephora as it is known to botanists. Robusta grows at lower altitudes than arabica and is more disease resistant. Robustas generally lack the acidity and complexity of the best arabica coffees. They are used mainly as unnamed constituents of the cheaper coffee blends. Small quantities of better quality robustas are sometimes used to give body and sweetness to some espresso blends.

The Question of Coffee Names

Fancy or specialty coffees are sold in two forms: blends, mixtures of coffees from more than one crop or region, and unblended coffees from a single crop and region (often called straight or varietal coffees). Unblended coffees are of most interest to home roasters because they facilitate knowledge (you know what you're roasting), adventure (they often taste intriguingly different) and control (once you get a feel for various individual coffees you can begin to assemble your own blends).

Let's Look at Each of These Naming Categories
Country of Origin

This designator (Kenya, Colombia, etc.) is easy to understand. It is usually the one descriptive term that always appears on store labels and coffee bags. However, countries are large, coffees in any given country are many, and market forces complex. Hence the various names and categories that follow. Click Here for more information on Coffee By Country.

Market Names

A market name is a traditional identifier that appears on burlap coffee bags and on exporters' and importers' lists. Most market names refer to region (Guatemalan Antigua or Mexican Oaxaca), a few to a port through which the coffee is traditionally shipped (Brazilian Santos) or even to a port through which the coffee once was shipped but isn't any more (Yemen Mocha; Mocha is a now closed and forgotten port on the Red Sea).

However, market names ultimately describe a coffee, not a place. Market names carry specific associations that include not only growing region, but certain taste characteristics. Some market names are more famous than the country of origin. Hawaiian Kona coffee is typically known by its market name, Kona, not by its country of origin, United States, or even by its state of origin, Hawaii.

Layers of Grade Names

Coffee is also sold by grade (Kenyan AA, Colombian Supremo, etc). Grade names can be based on evaluative criteria ranging from how big the bean is, to how high the coffee is grown, to how good it tastes (cup-quality).

Bulking coffee in large generic lots according to grade traditionally has been a way for coffee bureaucracies of growing countries to maintain centralized control over the coffee enterprise. However, the discipline of regulation as embodied in grading standards is being replaced or supplemented by the discipline of the market as embodied by competition among individual growers and grower associations for the attention of roasters and buyers in consuming countries.

Nevertheless, grade names remain an important element of coffee nomenclature. The more informative coffee store may identify a coffee by country (Guatemala), by market name (Antigua) and finally by grade (Strictly Hard Bean). As a rule, however, stores qualify the country name of a bulk coffee with only one adjective, either grade or market name.

Processing Method

The coffee bean is actually a seed of a small fruit coffee people call a cherry. How the fruit is removed from the bean and how the bean is dried are steps collectively known as Processing. Processing is one of the most important influences on coffee quality and taste.

In the wet method the various layers of skin and fruit around the bean are stripped off, before the bean is dried. Wet-processed or washed coffees tend to be more consistent, cleaner and brighter or more acidy in taste than dry-processed, natural or unwashed coffees, which are dried with the coffee fruit still adhering to the bean. The dried fruit is subsequently removed from the dry beans, customarily by machine. Dry-processed coffees are generally more idiosyncratic in flavor and heavier in body than wet-processed coffees.

Semi-washed coffees are a sort of compromise. The skin of the cherry is removed immediately after picking, but the flesh or pulp is allowed to dry on the bean. The dried pulp is later stripped off by a machine that temporarily wets the bean again. Some have argued that semi-washed coffees felicitously combine the full body and complexity of dry-processed coffees with the clarity and acidity obtained by the wet method.

How coffees are dried also may affect flavor and quality. As a rule, sun-dried coffees are considered preferable to machine-dried coffees.

Growing Conditions and Grade Names

Finally, the altitude at which coffee is grown figures in many grade names. Arabica coffee beans grown at higher altitudes typically mature more slowly than beans grown at lower altitudes, and the resulting denser bean may display more acidity and sometimes more complexity in the cup. Certainly growing altitude is only one aspect of many that influence coffee quality and flavor.

Organic is an important descriptive term in the contemporary coffee world. An organically-grown coffee must be certified by an international agency as having been grown without synthetic chemical fertilizers, pesticides, or herbicides. Somewhat lower yields and the considerable cost of the certification process account for the higher prices demanded for many organic coffees.

Estate and Cooperative Names

Owners of quality-conscious coffee farms enlist the aid of their colleagues in consumer countries to establish estate identities for their coffees. Estates sell their coffees directly to dealers without mixing them with other coffees from the same region, in theory insuring that these coffees reflect consistent growing conditions and processing practices.

A similar consistency is achieved by some cooperatives of smaller growers which market their coffees separately like estates through special arrangements with coffee dealers or roasting establishments. These designated cooperative coffees often support environmental and/or social agendas.

Some Good Things about Estate Coffees

Advantage number one: The estate concept helps identify coffees in precise terms. If you buy the same coffee a second time it most likely will display the same characteristics that attracted you to it in the first place.

A second advantage to buying by estate is that you can select coffees according to specific growing practices, social practices, or processing techniques.

A third advantage to estate coffees is that many offer superior or distinctive versions of regional taste characteristics.

Some Less-than-Good Things about Estate Coffees
Disadvantages to buying coffee by estate or cooperative?

Above all, if you become too concerned with buying only estate coffees you're limiting yourself. There are many outstanding coffees that simply are not marketed by estate.

A second disadvantage: price. Estate coffees may be good or different, but they may not be good or different enough to warrant the considerably higher price often asked for them.

Finally, some estate and designated cooperative coffees may be difficult to find green. Estates and cooperatives tend to work through a few selected wholesale roasters or dealers, sometimes only one, so access to these coffees is often limited.

Old vs. New: Names for Botanical Variety

All fine coffees derive from the arabica species, but not all coffees derive from the same botanical variety of that species. The fine coffee world is only beginning to market coffee by variety (or strain).

The connoisseurs and traditionalists raise the banner of what they call old arabica varieties, while some scientists, coffee growers, and government officials defend the usefulness of new arabicas.

As the world of fine coffee grows more sophisticated botanical variety will figure more prominently in identifying and marketing coffees, and aficionados may be in a position to make their own assessment of the impact of botany on quality.

The Ultimate Challenge: Adding Roast Names

Style of roast also can figure in the names that appear on store labels and signs. Most straight, unblended coffees are offered in a "normal" American medium to moderately-darkroast, in which case the roast style is not named. However, if an unblended coffee is offered in a style darker than normal the name of the coffee and the roast style both may appear: Sumatran Mandheling Dark Roast, for example.

Circumnavigating the Coffee Globe
Classic Coffees: Latin America and Hawaii

At their best, the classic coffees of Latin-American and Hawaii manifest full body, bright acidity, and a clean, straightforward taste. Their taste is based in part on the clarity of flavor achieved through wet-processing. Almost all fine Latin-American and Hawaiian coffees are washed, the exceptions being the better dry-processed and semi-washed coffees of Brazil.

The Big Classics

Generally fine Costa Rican, Guatemalan, and Colombian coffees are "big" coffees: full-bodied, with a bracing, rich acidity. They are best enjoyed at a medium to medium-dark roast, so that the power and subtle nuances of their acidity can be enjoyed.

The Caribbean Classics

The finest Caribbean coffees (best coffees of Puerto Rico, Jamaica, the Dominican Republic, and coastal Venezuela) are also powerful, but generally lower-toned, with their acidity held inside a deep, sweet, long-finishing richness.

True Jamaican Blue Mountain coffee, like the original Wallensford Estate Blue Mountain, is a big, rounded, intense, yet perfectly balanced example of the classic Caribbean taste.

The Gentle Classics

Good Brazilian, Peruvian, and Mexican coffees generally are lively rather than overpowering in acidity, lighter in body than the bigger classic coffees, and rounded in flavor. They make excellent darker roasts for espresso drinks. Their gentler acidity also makes them attractive coffees for those who like to drink their coffee black and unsweetened.

Other Central- and South-American coffees less often seen — from Nicaragua, Panama, Ecuador and El Salvador — also are typically softer, "smaller" versions of the classic taste.

The Hawaiian Classics

In the big picture Hawaiian coffees may be somewhat overpriced and perhaps a bit over-publicized. However, the best estate Hawaiian Kona is a powerful, rich, acidy example of the classic taste.

One of the great advantages of Hawaiian coffee for the aficionado is its accessibility. Growers are beginning to lavish the same attention on Hawaiian coffee as vintners did a couple of decades ago on California wines. It has become relatively easy to visit the farms, and proprietors increasingly provide plentiful and detailed information on their coffees.

Romance Coffees I: East Africa and Yemen

The coffees of Africa, Asia and the Malay Archipelago (Indonesia and Papua New Guinea) provide an array of romantic alternatives to the classic coffees of Latin America and Hawaii.

East Africa, together with Yemen, just across the Red Sea from Africa, produces some of the most distinctive of the world's coffees. Most are characterized by an extraordinary wine-like acidity, which can range from rough and wild in dry-processed Ethiopian coffees (Harar, Jimma), to rich and robust in Kenyan, to earthy and subtle in Yemen Mocha coffees. Similar wine-like notes enliven excellent arabica coffees from Zimbabwe, Malawi and Uganda.

Probably the best place for home roasters to begin in their exploration of East African coffees is Kenya. The state-of-the-art Kenyan coffee industry produces a plentiful yet superb product that is relatively easy to obtain green.

Ethiopia, the original home of Coffea arabica, produces the most varied range of coffee taste experience of any country — or indeed any region — in the world. Ethiopian Yirgacheffe is perhaps the world's most remarkable coffee. It is full-bodied, soft and rich, but its most striking characteristic is its extraordinary floral perfumes.

A last note of clarification: There are many variant spellings in English of Ethiopian and Yemeni names. Mocha may also appear as Moca, Mocca or Moka; Harar as Harer, Harrar or Harari; Jimma as Djimah or Jima; Gimbi as Ghimbi; Yirgacheffe as Yrgacheffe.

Romance Coffees II: India, Indonesia, New Guinea

Coffees of the arabica species grown in a crescent stretching from southwestern India across the Indian Ocean through Sumatra, Sulawesi and Java to New Guinea offer another kind of romance: the intrigue of softness, richness, and heavy, resonant body. These qualities reach their peak in the best coffees of Sumatra and Sulawesi (old name Celebes), which wrap a deep-toned acidity inside their extraordinarily rich body.

Romance Coffees III: Aged and Monsooned Coffees

Some aged (also called vintage) coffees have been held for as long as ten or more years before being exported or roasted, although three years is probably the norm. Eventually aged coffees begin to lose all acidy notes and turn dull and syrupy rather than rich. Even these coffees can be a pleasant change of pace drunk straight, however, and a delight in blends.

A taste profile somewhat similar to aged coffees is achieved in considerably less time by Indian exporters who "monsoon" their coffee. This exotic process involves holding the coffee in special warehouses open to the moist monsoon winds. In a few weeks the coffee yellows and transforms in taste.

You may want to try an aged and a monsooned coffee, first straight in order to understand their taste, then perhaps in a blend, where the weight and body of specially handled coffees can be used as a resonant counterpoint to brighter origins.

Blends and Blending

Coffee blends are crafted for two reasons: 1) to save money; 2) to produce a coffee that tastes better than (or at least different from) coffees of a single crop or region.

For large commercial roasters the cost issue is paramount. Since their coffees compete in supermarket chains, mass-market blenders attempt to create a decent coffee as cheaply as possible.

Specialty coffee roasters who sell smaller quantities of coffee in whole-bean form to a more demanding clientele also may want to cut costs by blending. But the primary goal of most specialty roasters is to produce a blend that tastes better or more balanced than any of its constituent coffees.

Other blends aim either to mimic characteristics of a famous and expensive coffee (Jamaican Blue Mountain Style Blend, meaning it has no Blue Mountain in it whatsoever), or stretch a costly coffee by mixing it with similar but cheaper beans (Hawaiian Kona Blend).

Blending at Home: Getting Started

For home roasters, subtlety in blending may only be possible after considerable tasting and experimentation. It is probably easier to get a feel for the process by combining very different but complementary coffees; a bright, acidy coffee with a fuller, deeper-toned coffee, for example.

To help that process along, here is a list dividing some well-known coffees into categories according to the particular qualities they might contribute to a blend. Obviously there are numerous ways of categorizing coffees for blending purposes; my list offers only one approach to a complex subject.

Category 1: Big classic coffees. These coffees contribute body, powerful acidity, and classic flavor and aroma to a blend. They perhaps make too strong a statement for use as a base for blends, but are excellent for strengthening and energizing less acidy coffees with softer profiles. I've omitted more expensive coffees like Jamaican Blue Mountain, Hawaiian Kona, and Puerto Rican Yauco Selecto, which given their cost probably should be enjoyed straight.
  • Guatemala (Antigua, Coban[AAAa] and Huehuetenango, other good Guatemalan coffees)
  • Costa Rica (Tarrazu[AAAu], Tres Rios[AAAi], other good Costa Rican coffees)
  • Colombia
  • Venezuelan Tachira[AAAFIRSTa], Merida[AAAe]
Category 2: Smaller classic coffees. These are "good blenders"; they establish a solid, unobtrusive base for a blend, and contribute body and acidity without competing with more individualistic coffees. When brought to a darker roast they often confer a satisfying sweetness.
  • Mexico (Oaxaca, Coatepec, Chiapas, Tapachula)
  • Dominican Republic or Santo Domingo
  • Peru (Chanchamayo for more acidity; Northerns for less)
  • Brazilian Santos (washed for more acidity, semi-washed for more body and sweetness)
  • Panama
Other possibilities are the better coffees from El Salvador, Ecuador, Nicaragua, Haiti and coastal Venezuela

Category 3: East African and Yemen coffees. Their powerful wine-like acidity makes these coffees a poor base for a blend, but excellent contributors of complexity and liveliness. Some, like Kenya, contribute considerable body as well. These coffees should be used with care in blends for darker roasts; they add a sharp bite attractive to many (including me), but may be distracting to others.
  • Yemen Mocha (adds richness and body as well as acidity)
  • Kenya (ditto above; acidity even more powerful)
  • Zimbabwe
  • Ugandan Bugishu
  • Ethiopian Harar (contributes rough, fruity, exciting acidity, but less body than the above)
  • Malawi
Category 4: Asian-Pacific and similar coffees. These add richness and body to a blend, and combine well with other coffees. Their deep-toned acidity will anchor and add resonance to the lighter, brisker coffees of category 2, and balance without blunting coffees in categories 1 and 3.
  • Sumatra
  • Sulawesi
  • Java arabica
  • New Guinea
  • Ethiopian washed coffees (best are Yirgacheffe and Limu)
  • Indian Mysore (unobtrusive; tends to add weight without power)
Category 5: Aged and specially-handled coffees. These add weight and body to a blend, and in the case of aged coffees richness and complexity as well. They are fun to experiment with in blends as a balance to category 1 and 3 coffees.
  • Indian Monsooned Malabar
  • Any good aged coffee
Click Here for more information on Coffee By Country

Blending for Taste and Variety

Clearly there are two ways to approach blending for taste alone: by system or by improvisation.

One systematic approach would be to start with a base coffee, as I suggest in the previous section, roast and drink it long enough to really know it, then experiment with adding other coffees to it, keeping notes as you go along. Another approach might be to begin with two coffees that complement one another, like the acidy Mocha and the softer, fuller Java of the original Mocha-Java blend (I'd make them a Kenya and a Sumatra, experiment with the proportions of the two constituents until you learn how they work together, then begin experimenting with adding a third coffee, again keeping notes so that a success can be built upon or duplicated.

Blending for Espresso and Dark Roasts

When blending for espresso cuisine the first question to consider is how you and your guests take your espresso. If you tend to drink it without milk and with very little sugar, you should avoid the big, acidy coffees in categories 1 and 3 and rely mainly on coffees in categories 2 and 4. Italian blenders prefer a base of Brazilian Santos, whereas West-Coast Americans typically rely on Mexican and Peruvian coffees. Good Indonesian coffees make splendid dark roasts, but are relatively expensive. Some Italians like to use high-quality robustas to smooth out their espresso blends.

On the other hand, if you drink your espresso with a good deal of hot milk and/or sugar, you may prefer a more pungent blend. On a base of Brazil, Peru, or Mexico, try adding a coffee from categories 1 or 3, perhaps either a Costa Rica or a Kenya or some of both. Go easy at first, adding a little more of the big, acidy coffee every session, until you achieve a taste you like for the way you drink your coffee. If you know you like an assertive, powerfully twisty espresso, start with a base of Kenya and gradually soften it with increasing amounts of a gentler coffee.

Of course how darkly you roast your espresso blend and what method you use to roast it also profoundly affects flavor.

Blends of Roasts

When I first came into coffee consciousness in the San Francisco Bay Area twenty years ago blends of dark- and medium-roasted beans were common. They are less so today, which is probably a pity. For me one of the most vibrant and exciting ways to enjoy a coffee is to mix darker and lighter roasted beans of the same origin, thus experiencing the coffee in its full range of roast taste.

Try it. Take the same coffee and bring two batches to a medium and to a dark or moderately dark roast, then blend the two. If you enjoy the result try varying the identity of the two coffees: Blunt the acidity of a Kenya by carrying it to a moderately darkroast, then combine one part of the darker-roasted Kenya with two parts of a medium-roasted Indonesian coffee, for example.

A Note on Decaffeinated Coffees

Coffees are decaffeinated in their green state. Three principal processes are used today in the world of fancy or specialty coffees: the traditional or European process, the water-only or Swiss-Water Process, and the CO2/water or Sparkling Water Process. All are consistently successful in removing all but a trace (2% to 3%) of the resident caffeine.

The traditional and water-only processes follow roughly the same steps: 1) The beans are soaked in hot water until both flavor agents and caffeine have been soaked out of them; 2) they are removed from the water, and the caffeine is removed from the hot water, leaving the flavor agents behind in the water; 3) the beans are then recombined with the water, where they reabsorb the now caffeine-free flavor agents. Once dried the beans are ready for sale and roasting.

The Sparkling Water Process (so-called because it uses water and Co2, the two components of sparkling water), soaks the caffeine out of the beans with compressed carbon dioxide, a ubiquitous and altogether harmless substance. Essentially, the carbon dioxide first selectively removes the caffeine from the beans, then water removes the caffeine from the C02, in a continuous cycle. Eventually the virtually caffeine-free beans are removed from the cycle, dried, and sent out into the world for roasting.

Taste, Roast, and Decaffeination

However powerfully it may affect our nervous systems, caffeine has very little effect on flavor. Isolated, it is a bitter, almost tasteless white powder. Coffee without it should taste virtually the same as coffee with it.

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