What is Coffee? A brown drink? A brown sweet drink? A brown bitter drink? A stimulant?
Where does coffee come from? Product of the Coffee tree Native of the African tropics Coffea arabica from highlands of Ethiopia Coffea robusta found in Uganda in 1895
Coffee & Islam Introduced to Arabia around 1000 AD Followed the spread of Islam around the Middle East and Mediterranean
The spread of Coffee Drinking 800?Used in Africa 1200Widespread in Arabia 1500Coffeehouses common in Turkey 1600Coffee introduced to Venice 1650Coffeehouses in London 1670First café in Paris 1683Siege of Vienna, coffee introduced 1700Dutch grow coffee in Holland
The spread of Coffee Growing 1713Gift of coffee tree to Louis XIV 1720Introduced to Martinique 1730Spread in Caribbean & to Brazil 1720 -1850Coffee production dominated by Dutch plantations in Dutch East Indies 1860Arrival of coffee rust in the Asia 1870Spread of coffee growing in S. America 1890Columbia and Brazil become major coffee producers.
Coffee Rust Under British rule Ceylon was found to have an ideal climate for coffee and by 1825 was intensively planted with coffee plantations. 1870 Ceylon was largest coffee producer in the world exporting 50 million kg By 1890 output was down to 5 million By 1910 coffee production had ceased
Coffee Rust Hemileia vastatrix Fungal pathogen of leaves Coffee ~ non deciduous, perennial, frost free, intensive plantations, monoculture. No effective fungicides Plantations decimated Reached Brazil in 1978 Modern control measures can limit spread
The Coffee Tree Coffea arabica Self fertile, tetraploid Small tree to 5m in understorey of upland forests ~ 2,000m altitude near equator In cultivation usually pruned to a bush Frost sensitive, temperatures not too cold or too hot,
Processing Dry: sun dry cherries & remove pulp when brittle Wet: Pulp and ferment 1 day to degrade flesh, then dry and polish beans to remove seed coat. Each cherry contains 2 coffee seeds or beans Raw Bean: light bluish grey colour
Torrefaction Roasting, 180°C, rotating mesh drum over gas furnace. Timing critical. –Light roast, 5 to 6 minutes –Medium roast, 8 to 10 minutes –Dark roast, 12 to 15 minutes Longer time gives stronger more bitter flavour, darker colour due to more browning reactions, caramelisation.
Caffeine Pharmacologically active ingredient of coffee (and tea, cocoa & cola) CNS stimulant Diuretic Cardiac stimulant Muscle relaxant
A Safe Drug Does not create dependency Toxicity above 200mg/kg body weight –(approx 50 x average consumption) No carcinogenic effect in humans Average levels 80mg per cup of coffee Average consumption around 200mg per day
Pharmacological Action Stimulant action mimics adrenaline Interaction with ß adrenoreceptors Reduces reaction time and speed of motor and mental tasks especially in fatigue. Improves concentration, causes insomnia. Habituation and withdrawal slight.
Other effects Diuresis from relaxation of tubules in kidney increasing filtration rate. Useful as bronchial muscle relaxant in asthma. Increases heart contraction rate, can trigger arrhythmias. Excess consumption (over 500mg per day) in pregnancy can affect placental blood flow.
Brewing Coffee Hot water extraction Must grind beans to powder to increase surface area for extraction extraction Fine grind, thorough extraction, stronger coffee, sediments more readily. Coarse grind, less rapid extraction, milder coffee, higher density.
Temperature & Pressure Pot, direct mix of boiling water and ground coffee, ready pour in a few seconds. Basic method for 1000 years. Variants –Cafetiere with a filter to retain grounds. –Boiling water and coffee together 1905 Espresso machines introduced in Italy use pressure generated by steam to force water through coffee on a filter plate.
Espresso 1908 Drip coffee maker using filter and slow percolation of water at low pressure just below boiling point. 1945 Piston operated high pressure espresso machine invented by Gaggia in Italy. Espresso more efficient extraction also includes more bitter flavoured extractives.
Coffee Types Variety used, eg Arabica or Robusta Region grown, African, American,Caribbean, Effect of environment, climate & soil. Roasting Blending Grinding
Instant Coffee 1938 Nescafe introduced by Nestle Freeze drying of coffee extract. Removal of moisture at low temperature preserves aroma. Produces soluble granules that dissolve readily
Decaffeinated Coffee Removes caffeine, preserves other flavours Liquid CO 2 excellent solvent for caffeine but not other aroma and flavour compounds Green beans are treated after heating with steam to aid extraction.
Where is it drunk? Sweden9 kg pca United States7 kg pca Western Europe4 kg pca United Kingdom2 kg pca
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