Sugar does not have a fixed melting point. Instead, as sugar increases in temperature, its molecules began to decompose. While heating sugar does produce a more fluid product known as caramel, it does not retain its chemical identity, which is a key element in the melting process.
Researchers had long been confused by the fact that sucrose would break down at different temperatures. They concluded that breaking the sugar down has more to do with the rate of heating than the temperature itself and that sucrose would begin decomposing at the same time that it would form caramel. The implications for confectioners is that keeping sugar at lower temperatures over a longer period of time produces a more reliable consistency and composition in caramel and other candy products.