Fruits may be preserved in syrups of varying strength depending on how long you wish to keep them and how sweet you want the end result to be. They are generally blanched or cooked in syrup, then preserved in a sealed jar covered in syrup, often thickened. The blanching and cooking process may be repeated multiple times, for a more candied fruit, or just once, for a fresher presentation. In general, the longer the cooking and the thicker the syrup, the longer the keeping.
Mostarda di frutta. To make this traditional northern Italian preserve, blanched fruits, usually firm ones like quince, pear, or apple that will retain their shape during repeated heating, are simmered in an 80 percent sugar syrup for 10 minutes every 24 hours, for three to five days. The fruit is weighed down and left to soak in the syrup between simmerings. Just before bottling the fruit in its honey-like syrup, mustard oil is added. See mostarda.