Orange Icing
1 orange rind 2 teaspoons lemon juice 1 cup powdered sugar white of 1 egg Grate orange rind and allow gratings to soak for some time in lemon juice; strain through cloth; stir juice, sugar and egg together and beat thoroughly. Pour on warm cake and spread with back of spoon.
A plain uncooked water icing of the kind that filled cake chapters before pasteurised eggs and stand mixers. The technique is sound, but the egg white is the problem.
- Raw egg white, never heatedThe white is beaten into sugar and juice and spread on cake that is merely warm from the oven — nowhere near the 160F needed to make raw egg safe. Warm cake surfaces sit in the temperature range where Salmonella is comfortable rather than killed, and the icing then stands at room temperature. A current recipe using pasteurised egg white or meringue powder should be used instead.
- Powdered sugarIn this period the term means finely ground sugar; modern confectioners' sugar is the direct descendant but carries 3 to 5 percent cornstarch, which thickens the mixture slightly more than the original would have.
- The rind and lemon juice trickGrating the zest and steeping it in the lemon juice, then straining through cloth, is a way of getting orange flavour without orange water — the oils leach into the acid. Only two teaspoons of juice are used, so most of the liquid here comes from the egg white; the recipe itself says to pour it on and spread it with the back of a spoon, so expect a soft spreadable glaze rather than a thin pouring one.
- YieldOne cup of sugar with a single white makes only a small quantity of icing — probably enough for the top of a single 8- or 9-inch layer rather than a whole two-layer cake.
Uncooked "water" and egg-white icings were common in American cake chapters from the 1870s through the 1920s, alongside boiled icing, which meant working sugar syrup to the soft-ball stage over a coal or gas range with no thermometer. Beating a raw white into powdered sugar was faster, needed no fire, and set to a hard shell as it dried, and many recipes of the period specify pouring it onto a still-warm cake, though the reason is not recorded. The New Royal Cook Book was published as promotional literature by the makers of Royal Baking Powder, one of a great many branded cookbooks distributed cheaply or free to build loyalty to a single leavening product; the cake section is the heart of such books, since baking powder was the ingredient being sold. Flavouring by steeping grated zest in acid and straining it out is said to have been used in households before commercial citrus extracts became reliable and inexpensive.