Sunday, January 25, 2015

Coffee (Coffea arabica)

The Conversation:
The vast majority of the brewed coffee we drink in Australia comes from the arabica species (Coffea arabica), despite 30% of world coffee production being the “robusta” variety (Coffea canephora).

Coffee is a member of the botanical family Rubiaceae, which is widely distributed in the tropics and subtropics. Other members of the family include chincona, the source of quinine, and gardenias, the boldly scented ornamental.

In terms of taste, connoisseurs agree that arabica produces a superior cup of coffee. Robusta beans produce coffee much more bitter and grainy in taste, but higher in caffeine than arabica.

And as the name suggests, robusta is a much more hardy plant than the delicate arabica, and less susceptible to insect pests (mostly due to its higher caffeine content) and fungal infections. It also grows in a wider range of environmental conditions and has a higher yield per acre than arabica, so is cheaper to produce and buy. On the open market green arabica beans sell for around A$5 per kilogram, and robusta beans retail for approximately A$2.50 per kilogram.

Australia only grows arabica coffee. The cool climate and absence of insect and fungal pests create ideal growing conditions. Flowering occurs for a period of a couple of days sometime between October and December, depending on spring rainfall.

The coffee cherries begin to ripen in June and are harvested three to four months later depending on the season. The coffee fruit are a deep red purple colour when they are ready for harvest.


Wake up and smell the coffee
Without its smell, coffee would have only a sour or bitter taste due to the organic acids. The rich satisfying sensation of coffee is almost entirely due to the volatile compounds produced when we roast coffee beans.

Approximately 800 different compounds are produced in the coffee-roasting process. These thermal degradation reactions decompose sugars and proteins to form the volatile compounds that we smell.

The compounds that are formed in the roasting process are very similar to any other compound that is formed in the cooking process. The smell of baking bread is from compounds produced when a sugar reacts with a protein in what is called a Maillard reaction.


More information:
» The Conversation: The perfect cup of coffee boils down to four factors
» Paste Magazine: Seven Coffee Brewing Methods

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