If fruit is of good quality and the sugar pure, there is very little scum on the fruit during the cooking, but usually at some stage of preserving or canning a film rises to the surface. It is best to skim it off as soon as it begins to gather, take it up with a skimmer or clean spoon and pour into a clean bowl. The pure juice it contains will soon settle on the bottom of the bowl. Carefully draw the scum off and return the juice to the kettle. If much accumulates, and it seems best not to return the juice, it can be cooked separately with half as much sugar and used for pudding sauce or for fruit farina pudding.