Candy is a confection made from a concentrated solution of sugar in water, to which flavourings and colorants are added. Other ingredients can be added like milk, to obtain caramel, or gelatins or other thickeners to obtain marshmallows or gummies. Candy Technology uses scientific knowledge drawn from chemistry, physics or material science to produce one of the world’s favourite treats.

The main ingredient of candies is the sugar syrup – a very highly concentrated sugar solution (usually above the saturation point).

The use of sugar in concentrated solutions on confectionery is considered by many as an art only mastered by great chefs in trendy restaurants, or older women who devoted their lives to cooking in small pastry shops located in small villages. However, this could not be farther from the truth: there is a lot of science behind the art of sugar syrups production. Such production involves the use of high temperatures with subsequent water evaporation. The extent of sugar degradation and the final water content in sugar syrups are critical parameters that influence aroma, sweet taste, mouthfeel and texture of the final products.

The sugar degradation occurring due to the heat treatment during the production of candies can follow to main reaction pathways: the caramelization reaction (if only sugars are present in the formulation) or the Maillard reaction. The latter is a type of reaction that occurs when sugars are heated with milk or other high protein content ingredient. Both reactions are important for the formation of the much appreciated “caramel” aroma and taste.

The final water content and also the type of thermal treatment of the candy will decide on how the molecules interact with each other, i.e. to the “molecular architecture”. This is in the end what will determine the candy texture: Amorphous candies, with a disorganized molecular structure, can be described as chewy, hard, or brittle (examples are caramels or toffees). Crystalline candies present the sugar molecules microscopically organized in crystals (e.g. fudge or fondant).

Candies are not only sweet, but they can also be a lot of fun! Learn more on candies and their production on the following links:


Enjoy your candy!


This text was prepared by Mafalda Quintas, Catholic University of Portugal, College of Biotechnology, Porto, Portugal.

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Videos about Candy:




                         "How It's Made: Hard Candy"                                                           "How It's Made: Gummi Bears"



                 Bytesize Science: "Hard Candy Chemistry"                                      Bytesize Science: "Candy Corn Chemistry"