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. Candy canes and after-dinner mints are common examples of such confections.
An opaque but satin- or silk-like sheen results when the cooled but malleable syrup is repeatedly pulled and folded back onto itself. This working incorporates some air bubbles, and these in turn encourage the formation of tiny sucrose crystals. Both bubbles and crystals interrupt the candy structure, giving it a crisp, light quality and making it easier to break between the teeth. (See “Sugar Work” below.)