On Food and Cooking

The more sugars and the less water a
candy contains, the harder its texture.
Glucose sugars and chains (corn syrup)
are included in candy syrups to prevent
sucrose crystallization (hard candies,
gummy candies) or to limit it (caramels,
fudge, fondant).
Intentionally Crystalline Hard Candies The
development of crystals is considered a defect
in many hard candies, and results from too
little interfering corn syrup, or the
introduction of seed crystals from the pan
sides, or too much moisture in the syrup. But
some hard candies are intentionally
manipulated to form tiny crystals, which give
the candy a “short,” more crumbly texture.