Simple. Chemistry. OK, not so simple, but chemistry nonetheless; more specifically, the chemistry of sugar. Sugar undergoes a delicious transformation when heated, releasing a flood of flavourful compounds as it breaks down and reacts with amino acids in the bread. It’s the subtle, yet seductive scent of caramelized bread that widens the eyes and triggers the appetite. Bread with higher sugar content browns faster and is more prone to carbonizing while moister, denser loaves require a higher setting or more time toasting. Bread with more of the air pockets and cavities caused by the fermentation of yeast allows heat to permeate more easily, and can result in a drier toast.