Coffee بُنقهوة ّ Foods, Facts & Fallacies YSCN 0006
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 • 1200 Widespread in Arabia • 1500 Coffeehouses common in Turkey • 1600 Coffee introduced to Venice • 1650 Coffeehouses in London • 1670 First café in Paris • 1683 Siege of Vienna, coffee introduced • 1700 Dutch grow coffee in Holland
The spread of Coffee Growing • 1713 Gift of coffee tree to Louis XIV • 1720 Introduced to Martinique • 1730 Spread in Caribbean & to Brazil • 1720 -1850 Coffee production dominated by Dutch plantations in Dutch East Indies • 1860 Arrival of coffee rust in the Asia • 1870 Spread of coffee growing in S. America • 1890 Columbia 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,
Fruiting • Produce flowers when 4 years old • Flowering coincides with onset of rainy season • Fruit ripen in 8 months • Produces bright red “cherry”
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 CO2 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? • Sweden 9 kg pca • United States 7 kg pca • Western Europe 4 kg pca • United Kingdom 2 kg pca