When sugar is burned, chemical changes take place, depending on if the sugar is burned in a complete or an incomplete combustion reaction. During a complete combustion reaction, sugar is transformed into CO2 and H20. In an incomplete combustion reaction that uses lower heat, ring polymerization and charring may occur.
Chefs take advantage of the oxidation process for burning sugars. The process is called "carmelization" and brings out unique flavors when the sugar is burned. Carmelized sugars get their flavors from the products formed in the reaction, including aldehydes, carboxylic acids and ketones. All sugars are carbohydrates, having carbon, hydrogen and oxygen in their ratios.