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Lemon Filling
2 egg whites 2 tablespoons boiling water 1 cup powdered sugar 1 teaspoon cold water 2 teaspoons gelatine 2 tablespoons lemon juice grated rind 1 lemon Cover gelatine with cold water; dissolve in boiling water; add to beaten whites with sugar, rind and juice.
This is an uncooked meringue-type filling, and that is the problem with it: the egg whites never reach a temperature that would make them safe.
- The whites are never cookedTwo tablespoons of boiling water stirred into two beaten whites plus a cup of sugar loses its heat almost immediately and pasteurizes nothing. The finished filling is raw egg white, spread between cake layers and then held at room temperature, which is where Salmonella in shell eggs is most at home.
- Gelatine does not sterilize anythingThe gelatine here is a setting agent only. It is dissolved in the same two tablespoons of boiling water and then stirred into the raw whites; nothing in that sequence brings the eggs to a safe temperature.
- Sugar is not a preservative at this ratioA cup of powdered sugar against two whites and two tablespoons of juice gives a wet, low-solids foam. It will not keep, and the acidity of the lemon juice does not reduce pathogen risk in any meaningful way.
- Who it is riskiest forUncooked egg white is a poor bet for anyone pregnant, elderly, very young, or immunocompromised — precisely the mixed audience a layer cake usually gets served to.
- What to do insteadIf you want a lemon filling of this type, use a current recipe built on a cooked lemon curd or on pasteurized egg whites. Do not adapt the method above.
- Reading the original measuresFor context rather than for use: "powdered sugar" in American books of this era is generally the fine granulated sugar we would call caster, not modern confectioners' sugar with its cornstarch. "2 teaspoons gelatine" means loose granulated gelatine, close to a full modern envelope.
Lowney's Cook Book was compiled by Maria Willett Howard and published in 1907 for the Walter M. Lowney Company of Boston, a chocolate manufacturer — one of a long line of American cookbooks issued by food companies to build a market for their product. Fillings like this one belong to a whole family of turn-of-the-century cake fillings and "boiled" frostings that leaned on beaten egg white for volume: cheap, quick, and unbaked. The gelatine is the giveaway that this was meant to hold its shape between layers rather than be eaten by the spoonful. The connection between raw egg and specific pathogens was not understood as it is now, and recipes like this stayed in print for decades.