Caramelization

Lore & Background

Caramelization is a complex, poorly understood process that produces hundreds of chemical products. It includes reactions such as equilibration of anomeric and ring forms, sucrose inversion to fructose and glucose, condensation reactions, intramolecular bonding, isomerization of aldoses to ketoses, dehydration reactions, fragmentation reactions, and unsaturated polymer formation. The process is temperature-dependent, with specific sugars each having their own point at which reactions begin to proceed readily. Impurities in the sugar, such as the molasses remaining in brown sugar, greatly speed the reactions. Reactions are also sensitive to the chemical environment; the rate of caramelization is generally lowest at near-neutral acidity (pH around 7) and accelerated under both acidic (especially pH below 3) and basic (especially pH above 9) conditions.

Reader's Guide

Caramelization is significant in cooking and food production for its ability to impart a distinctive butter-like flavor and brown color to a wide range of foods. Its uses include caramel sauce, confiture de lait and dulce de leche (caramelized sweetened milk), caramel candies, crème caramel and crème brûlée (custard dishes topped with sugar caramelized with a blowtorch), caramelized onions (requiring 30 to 45 minutes of cooking), caramelized pears, cola (some brands use caramelized sugar for color), latik (a sweet syrup of sugar and coconut milk used in Filipino desserts), and dodol (a toffee made with cane sugar, rice flour, and coconut milk from Indonesia). The process is distinct from the Maillard reaction in that it is pyrolytic rather than involving amino acids. Its complexity and sensitivity to temperature and pH make it a subject of ongoing study, with hundreds of chemical products generated during the reaction.

Did You Know?

• Caramelization produces three groups of polymers: caramelans (C24H36O18), caramelens (C36H50O25), and caramelins (C125H188O80).
• The volatile chemical diacetyl, known for its intense butter-like taste, is released during caramelization.
• When caramelization involves the disaccharide sucrose, it is broken down into the monosaccharides fructose and glucose.
• The rate of caramelization is lowest at near-neutral acidity (pH around 7) and accelerated under both acidic (pH below 3) and basic (pH above 9) conditions.