How sugar transforms with heat
Caramelization is the thermal decomposition of sugar, a browning process distinct from the Maillard reaction because it involves no proteins or amino acids, only sugar and heat. As table sugar (sucrose) is heated past its melting point, near 160 to 170 degrees Celsius, it begins to break down and form hundreds of new aromatic and colored compounds.
The process moves through visible stages, from a clear melt to a pale golden syrup, then amber, then a deep brown. Each stage corresponds to a higher temperature and a more complex, more bitter flavor profile.
Reading the temperature stages
Light caramel, around 170 to 180 degrees Celsius, is sweet and mild and suits sauces and candies. Amber caramel, near 180 to 190 degrees Celsius, develops the classic nutty, toasty notes prized for desserts. Dark caramel, approaching 190 to 200 degrees Celsius, turns increasingly bitter as sweetness gives way to roasted, almost burnt flavors used sparingly for color and depth.
Push past this range and the sugar carbonizes into an acrid, blackened mass. Because the window between stages is narrow, caramelization is largely a matter of watching color and pulling the pan from the heat at the right moment.