Quince is very rich in pectin, the substance that allows jams and jellies to thicken or jell. Sugar also acts as a jelling agent and a preservative.
In Sicily, quince jam is cooked until very thick, stirring constantly, and is molded in specially made decorative clay molds. The molds can have a design, or a message such as Buon Anno, which means Happy New Year. When the jam is cold, it’s unmolded, placed on a tray, and allowed to air dry. It is then eaten like candy