Many households have their own recipes for Christmas pudding, some handed down through families for generations. Essentially the recipe brings together what traditionally were expensive or luxurious ingredients — notably the sweet spices that are so important in developing its distinctive rich aroma, and usually made with suet. It is very dark in appearance — very nearly black — as a result of the dark sugars and black treacle in most recipes, and its long cooking time. The mixture can be moistened with the juice of citrus fruits, brandy and other alcohol (some recipes call for dark beers such as mild, stout or porter).