Sweet preserve recipes and jams call for warmed sugar.
While warming the sugar before adding it to the pan is not absolutely imperative in a jam recipe and won't affect the final outcome, it does speed up the dissolving process. The sugar dissolves more quickly and, being warm, will not reduce the temperature of the fruit mixture as much as if you had added cold sugar. To warm sugar, spread it in an even layer in a deep-sided baking dish and warm in a slow oven 150C for about 10 - 15 minutes, or until warmed through. Do not overheat the sugar or it will start to lump together. To make sure, stir the sugar once or twice while it is warming.
To save time, warm the sugar while you are cooking the jam. Do not add the sugar until the fruil has softened. If sugar is added before the fruit is fully soft, it will stay firm. Regular granulated sugar is used in our jam, jelly and preserve recipes unless otherwise specified. Caster sugar is used in some recipes for quicker dissolving and better clarity.
Tip: Brown sugar is used mostly in chutneys, pickles and relishes to enhance the flavours and give a rich colour.
Hope this helps - good luck!