During roasting, caramelization occurs as intense heat breaks down starches in the bean, changing them to simple sugars that begin to brown, changing the color of the bean.[50] Sucrose is rapidly lost during the roasting process and may disappear entirely in darker roasts. During roasting, aromatic oils, acids, and caffeine weaken, changing the flavor; at 205 °C (400 °F), other oils start to develop.[49] One of these oils is caffeol, created at about 200 °C (392 °F), which is largely responsible for coffee's aroma and flavor.[16]
Folded-over bags, a common way consumers often purchase coffee, is generally not ideal for long-term storage because it allows air to enter. A better package contains a one-way valve, which prevents air from entering.[53]
