Coffee left Yemen and never went back

Coffea arabica originates in the highlands of Ethiopia, where it grows wild and where traditions of use are long established. Cultivation and the practice of roasting and brewing the beans are documented in Yemen from around the fifteenth century, associated particularly with Sufi communities who used it to stay awake for night devotions.

From Yemen it spread through the Ottoman world, reaching Cairo, Damascus, Istanbul and then Europe over the following century and a half.

The institution travelled with the drink

What spread was not only a beverage. The coffee house arrived as a package: a public space where men gathered, sat for extended periods, talked, played games, listened to music and conducted business.

This was a genuinely new kind of space in most places it appeared. It was not a tavern, since no alcohol was involved and the drink did not impair. It was not a private house. It was open to anyone who could pay for a cup, which made it socially mixed in a way few venues were.

Authorities noticed. Coffee houses were periodically closed or restricted in various places on the grounds that they encouraged idleness, sedition or both. Those closures are informative: the concern was consistently about what people did in them rather than about the drink.

In Europe the same pattern repeated. London coffee houses in the seventeenth and eighteenth centuries functioned as venues for commerce, news and argument, and several substantial institutions grew out of gatherings held in them.

The commodity

Yemen held an effective monopoly on cultivation for a considerable period, and exports moved through the port of Mocha, which is why the name attached to the coffee.

That monopoly was broken by the removal of viable seedlings and their establishment in colonial plantations — in Java, then in the Caribbean and Latin America. The details of specific plants and voyages have acquired a certain amount of legend, and the general outcome is clear: within a century, production shifted overwhelmingly to plantation agriculture in the Americas and Southeast Asia.

That shift was built on colonial land appropriation and on enslaved and coerced labour, and the structure of the industry — large numbers of small growers with little market power selling into a commodity system dominated by a few buyers — has roots in that period.

The two species

Arabica accounts for the majority of production and nearly all specialty coffee. It grows at altitude, is susceptible to disease and to temperature, and produces more complex flavour.

Robusta tolerates lower altitudes, heat and disease far better, yields more, and contains more caffeine. It is generally harsher in flavour and is used heavily in instant coffee and in espresso blends where its body and crema are wanted.

Climate change is shifting this balance. Arabica's requirements are narrow, and projections of suitable growing area under warming scenarios are not encouraging. Considerable work is going into breeding and into other species that might tolerate warmer conditions.

Preparation traditions

The Ethiopian ceremony, where beans are roasted, ground and brewed in front of guests, served in three rounds, over a period of an hour or more. It is a hosting ritual rather than a beverage service.

Finely ground unfiltered coffee boiled in a small pot, found across Turkey, the Levant, the Balkans and beyond under many names, frequently spiced with cardamom.

Espresso, a twentieth-century Italian development requiring pressurised extraction, which produced its own café culture and its own extensive set of rules about what is drunk when.

Filter methods of many kinds, and the various regional variants — sweetened condensed milk in Vietnam, egg in some Scandinavian traditions, spices in others.

Each of these is a coherent tradition and none is a degraded version of another, though people will argue about it at length.

The processing step that decides most of the flavour

Coffee is a fruit. The seed has to be separated from the pulp, and how that is done substantially determines what the coffee tastes like.

Washed processing removes the fruit before drying, producing cleaner, brighter, more acidic coffee.

Natural or dry processing dries the whole fruit with the seed inside, producing heavier, fruitier, sweeter results. It requires reliable dry weather and it is the older method.

Honey and various intermediate methods remove some of the fruit and leave some.

The difference between a washed and a natural coffee from the same farm and the same trees is larger than most people expect, which is a useful thing to know when buying.

The economics now

Coffee is grown largely by smallholders and consumed largely in wealthy countries, with most of the value added after export.

Commodity prices are volatile and have at times fallen below production cost, which produces predictable consequences: growers abandoning coffee, ageing farms not replanted, and young people leaving.

Various certification and direct trade arrangements attempt to address this with mixed results, and the specialty market pays substantially more for a small share of total production. The scale mismatch between the specialty conversation and the bulk market is large, and worth remembering.