By Harold McGee
Hard candies are the simplest noncrystalline candies; they include hard drops, clear mints, butterscotch, bonbons, lollipops, and so on. Hard candy is made by boiling the syrup high enough that the final solid will contain only 1 or 2% moisture, then pouring the syrup onto a surface and cooling it down, kneading in colors and flavors while it’s still malleable, and shaping it. The very high sugar concentration makes this syrup liable to form crystals at the slightest excuse, so a substantial proportion of corn syrup is used to prevent this and produce a clear sugar glass. The high cooking temperatures also encourage caramelization and a yellow-brown discoloration, which are not desirable in these candies; they’re often manufactured under reduced pressure, which allows them to reach the proper sugar concentration at a lower temperature.