Jane Parker, a flavour chemist at the University of Reading explains, it’s all down to molecules ‘jumping’ off whatever it is you’re smelling (by evaporation), drifting through the air (by diffusion) and flying up your nose. It’s just as hard to say that one group of chemicals always smells good, though – at lower levels, they may lend a tropical note, making you think of tropical-flavoured drinks or sweets, or contribute to