Swiss meringue

Why

For Swiss meringue, the whites and sugar are first warmed over a water bath to roughly 71 °C and only then whipped until cool. The heat dissolves the sugar completely, and the sugar in turn protects the proteins, so they partly unfold without setting; the result is a dense, glossy and very stable foam. French meringue is whipped cold with the sugar added gradually – it tends to be lighter and bigger but less stable, which makes it best for folding into batters and for baked meringues. Swiss meringue has less volume but holds up as a cake topping, a frosting or the base of a buttercream; once the mixture reaches about 71 °C on a thermometer, the salmonella risk also drops considerably. Without sugar, the whites would start to set at that temperature – sugar pushes their coagulation point higher.

How to do it

• Use a clean glass or metal bowl; fat and yolk spoil this foam too.
• Use roughly one and a half to two times as much sugar as egg white by weight.
• Set the bowl with the whites and sugar over a pan of gently simmering water, without the bottom touching the water.
• Whisk constantly until a thermometer reads about 71 °C and the sugar has fully dissolved. Test for grains only on a drop cooled on a spoon – at 70 °C the mixture is sticky and burns.
• Take the bowl off the heat and whip until the mixture is cool and holds a firm, glossy peak.

If it goes wrong

If white flecks have set on the side of the bowl, strain the mixture through a sieve and carry on whipping. A meringue that won't hold a peak once cool usually just needs more time – Swiss meringue is slower than French. If fat got into the whites, there's no rescue: start again with a clean bowl.