Caramelized crust on a Crème brûlée
Caramelized crust on a Crème brûlée

Caramelization is a process of browning of sugar used extensively in cooking for the resulting rich, butter-like 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 (known for its intense, butter-like taste) are released, producing the characteristic caramel flavor.[1]

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.[2]


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Mirepoix (carrots, onions, and celery) being caramelized

Caramelization is a complex, poorly understood process that produces hundreds of chemical products, and includes the following types of reactions:

Effects of caramelization

A partially caramelized lump of sugar

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.

Caramelization temperatures[3]
Sugar Temperature
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,[4] 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.[5]

Uses in food

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Caramelization is used to produce several foods, including:

See also


  1. ^ Miller, Dennis (1998). Food Chemistry: A Laboratory Manual. Wiley-Interscience. ISBN 978-0471175438.
  2. ^ Woo, K. S.; Kim, H. Y.; Hwang, I. G.; Lee, S. H.; Jeong, H. S. (2015). "Characteristics of the Thermal Degradation of Glucose and Maltose Solutions". Prev Nutr Food Sci. 20 (2): 102–9. doi:10.3746/pnf.2015.20.2.102. PMC 4500512. PMID 26175997.
  3. ^ Harold McGee. "On Food and Cooking", 2nd Edition (2004), Scribner, New York, NY. "Sugar, Chocolate and Confectionery", Page 656.
  4. ^ McGee, Harold. "Caramelization: new science, new possibilities". Archived from the original on October 28, 2018. Retrieved May 10, 2019.
  5. ^ Villamiel, M.; del Castillo, M. D.; Corzo, N. (2006). "4. Browning Reactions". In Hui, Y. H.; Nip, W-.K.; Nollet. L. M. L.; Paliyath, G.; Simpson, B. K. (eds.). Food biochemistry and food processing. Wiley-Blackwell. pp. 83–85. ISBN 978-0-8138-0378-4.
  6. ^ Scocca, Tom. Layers of Deceit: Why do recipe writers lie and lie and lie about how long it takes to caramelize onions? Archived October 1, 2018, at the Wayback Machine, May 2, 2012.
  7. ^ Child, Julia. "French Onion Soup". Archived from the original on May 2, 2012. Retrieved March 8, 2017.
  8. ^ Farley, Jennifer (October 10, 2016). "Caramelizing Pears". Stemilt. Archived from the original on February 14, 2019. Retrieved October 27, 2016.