Orange Icing
One tablespoon of orange juice, 1 teaspoon of lemon juice, yolk of 1 egg; a little orange rind, 1½ cups of confectioners' sugar. Beat until smooth. ALUME
This is an uncooked icing bound with a raw egg yolk, a common construction in turn-of-the-century American cookbooks and one that no longer meets modern food-safety practice.
- Raw yolk, never heatedThe yolk is the only binder here and nothing in the method brings it above room temperature. Shell eggs can carry Salmonella both on the shell and inside the egg itself, and an icing that is beaten cold and spread on a cooled cake never reaches a temperature that would reduce that risk.
- The acid does not make it safeA tablespoon of orange juice and a teaspoon of lemon juice against a whole yolk and a cup and a half of sugar is nowhere near acidic enough to be considered a kill step. Citrus in an icing is there for flavour, not preservation.
- It sits outIced cakes are kept at room temperature for a day or more, which is exactly the condition under which a raw-yolk coating becomes a problem. Refrigeration would slow but not undo the initial hazard.
- If you want an orange icingUse a current recipe: modern versions are built on butter or on pasteurised egg product, or omit the egg entirely and rely on juice and sugar alone.
- Reading the originalConfectioners' sugar is broadly the same product sold today, though grades have varied over time. "A little orange rind" means the coloured zest only, finely grated, with none of the white pith beneath it.
- YieldA cup and a half of sugar makes a small quantity of icing, roughly enough for the top of a single 8-inch cake, or thinly over top and sides.
Uncooked icings thickened with a raw yolk or white were standard in American household cookery from the mid-nineteenth century until well into the twentieth. The yolk did two jobs at once, giving the icing a deep colour that reinforced the orange and enough emulsifying power to keep it smooth and spreadable without cooking. Boiled icings and meringue frostings existed alongside them but demanded a sugar thermometer or a practised eye, so the beaten uncooked version stayed popular in home kitchens for its sheer speed. Awareness of egg-borne illness came much later; the shift away from raw-egg frostings in printed recipes is largely a development of the last few decades of the twentieth century.