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The Chemistry of Coffee Roasting
Transcript of The Chemistry of Coffee Roasting
Coffee Roasting Coffee preparation may appear to be simple but the chemistry behind it is very complex Scientist study the different CHEMICAL and THERMAL REACTIONS that happen inside a coffee during roasting to make the most delectable taste This is when caramelization begins (338-392F) At this point water and carbon-dioxide fracture, causing Pyrolisis to begin. Arabs
Roasting Coffee Beans
Applying heat to coffee beans, grinding the bean and boiling the grounds in water, releases the sweet taste and aroma of the coffee http://www.caffepronto.com/education/roast.php Turning a Yellow color The first stage is ENDOTHERMIC http://www.coffeeresearch.org/coffee/roasting.htm http://www.sweetmarias.com/coffee_chemistry/tweaking_coffees_flavor_chem.html PROCESS Whenever the beans are first exposed to heat the moisture in the bean begin to evaporate As the TEMPERATURE of the bean rises the bean starts to expand, undergoing a CHEMICAL REACTION called the first crack http://coffee.wikia.com/wiki/Roasting (destruction by heat) FIRST CRACK During the first crack the bean doubles in size, turns light brown and experiences WEIGHT loss. SECOND CRACK http://www.coffeeresearch.org/coffee/roasting.htm http://www.coffeeresearch.org/coffee/roasting.htm During Pyrolisis the beans start to release oils, causing smoke to be released
In this stage the internal temperature exceeds 350
Eventually the bean will go through many small internal explosions
Called the second crack http://coffee.wikia.com/wiki/Roasting COOLING PROCESS Within two or three minutes from the roast the beans are brought down to a lower temperature. Cooling is done through a fan But quenching, which is a method were you only use water, is a quicker way of reducing the temperature CHEMICAL CHANGES Loss of water content
Heat transfer during roasting can involve : CONDUCTION, CONVECTION, RADIATION The destruction of initial COMPOUNDS start to turn to volatile compounds. http://atrium.lib.uoguelph.ca/xmlui/bitstream/handle/10214/3584/May%205,%20thesis--Niya%20Wang.pdf?sequence=1 The CARBOHYDRATES
of the bean are affected
by becoming caramelized http://atrium.lib.uoguelph.ca/xmlui/bitstream/handle/10214/3584/May%205,%20thesis--Niya%20Wang.pdf?sequence=1