Caramelization is a process of browning of sugar used extensively in cooking for the resulting sweet nutty flavor and brown color. The brown colors are produced by three groups of polymers: caramelans (C24H36O18), caramelens (C36H50O25), and caramelins (C125H188O80). As the process occurs, volatile chemicals such as diacetyl are released, producing the characteristic caramel flavor.
Like the Maillard reaction, caramelization is a type of non-enzymatic browning. Unlike the Maillard reaction, caramelization is pyrolytic, as opposed to being a reaction with amino acids.
When caramelization involves the disaccharide sucrose, it is broken down into the monosaccharides fructose and glucose.
Caramelization is a complex, poorly understood process that produces hundreds of chemical products, and includes the following types of reactions:
The process is temperature-dependent. Specific sugars each have their own point at which the reactions begin to proceed readily. Impurities in the sugar, such as the molasses remaining in brown sugar, greatly speed the reactions.
|Fructose||105 °C (221 °F)|
|Galactose||160 °C (320 °F)|
|Glucose||150 °C (302 °F)|
|Sucrose||170 °C (338 °F)|
|Maltose||180 °C (360 °F)|
Caramelization reactions are also sensitive to the chemical environment, and the reaction rate, or temperature at which reactions occur most readily, can be altered by controlling the level of acidity (pH). 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.
Caramelization is used to produce several foods, including: