Crystallizations of crystalline candies

Crystalline candies have an organized sugar structure that is formed through the process of crystallization. Crystalline candies such as fudge or fondant are smooth, creamy and easily chewed.

Crystallization is a complex process with many interrelate factors. The nature of the crystallizing substance is important of crystallization. The rate of crystallization is the speed at which nuclei grow into crystals.

Crystalline candies are evaluated on their smoothness. The sugar crystals are so tiny that they cannot be felt by the tongue.

One of the factors influencing the smoothness of crystalline candies is the point when crystallization begins. If crystals are formed very rapidly, the candy will become locked into a fine crystalline structure that will change very little over time.

When making candy, it is important to use a pan with even heating characteristics to ensure accurate, even temperature readings. A small error of 1 to 2 degrees below the correct temperature will cause the candy to be too soft; conversely cooking at 1 to 2 degrees above the required temperature will create a crumbly or hard product.

In order to control the rate of crystallization and the formation of small crystals and to ensure a smooth texture, interfering agents are incorporated into a sugar formulation. Chemical interfering agents produce invert sugar (glucose and fructose), thereby slowing crystallization and increasing the solubility of solute.
Crystallizations of crystalline candies

Crystallization of sugar

Crystallized sugar looks like damp, white sand. It happened often as a result of not being properly melted during cooking. If even one sugar crystal comes into contact with cooked syrup, it can start a chain reaction that turns the whole thing into a mass of sugar crystals.

Crystallization can occur when granulated particles of sugar come in contact with melted particles, or when the melted sugar is agitated too much during cooking.

This can be controlled by a process called inversion. Inversion is a chemical change to regular sugar into another form of sugar that resists crystallizing.

If an acid, such as cream of tartar or lemon juice, is added to a syrup before or during cooking, some of the sugar is inverted. Glucose or corn syrup may also be added to control crystallization in boiling syrup. 

Crystallization also may be prevented by brushing down the sides of the pan with water during the cooking process.

Sugar is purposely crystallized during the cooking process for crystalline confections like fondants and fudge because controlled crystallization forms thousands of microscopic sugar crystals that create smooth and creamy texture.

Conversely, crystallization must be avoided during the production of non-crystalline confections such as caramels, hard candies and toffees.
Crystallization of sugar