• Every type roasts at a different rate because of a different  density
• When a bean reaches its individual temperature it cracks, like popcorn pops
• This first ‘crack’ is caused by the physical expansion of the bean as water and carbon dioxide split and carbon dioxide is released (ah, it’s everywhere this stuff!).  This first crack opens the central divide of the bean and loosens the very light papery sheath that encloses it and which becomes a waste chaff that’s beaut for compost – fluffy, light, easy to carry and high in carbon; we use it every week in our compost bins here
• After this first crack the coffee may be made and drunk
• If the bean is heated further the flavour is heightened as the sugars inside the bean caramelize and the bean cracks a second time
• The second crack is the roasting goal of commercial roasters who roast for espresso coffee and the more evenly the heat is applied to the whole bean the more flavoursom the coffee
• Home roasters may be a hot pan in which you stir the beans as fast as possible; a popcorn popper; or a combination of a gas jet like that used to strip paint and a bread maker go well together;

For more information: Coffee Snobs  – www.coffeesnobs.com….au ,  coffeegeek.com…  , home-barrista.com…  ,   café-grendel.blogspot.com