Molecular Gastronomy: Custard Ravioli Spherical Recipe

Custard Spherical Recipe

Alginate bath:
5g (0.18 ounces) Sodium alginate molecular gastronomy kits available here
25g (0.88 ounces) or 2 Tbsp sugar
1 litre (0.26 gallons) distilled water

Mix together the sugar and sodium alginate (this helps to stop it clumping). Put half the water in a blender and sprinkle the surface with a little of the sodium alginate mixture – blend 10 secs, repeat until all of the alginate is added. Add the remaining water and blend for 3 minutes. Pour into a container and refrigerate for a couple of hours. This allows the alginate to rehydrate and the air bubbles to dissipate.

Custard:
4 egg yolks
1/3 cup or 72g (2.54 ounces) sugar
1 cup or 250ml cream
vanilla
5g (0.18 ounces) calcium lactate
1 tablespoon or 15ml water
Presentation (optional): I served the sphericals with sponge, strawberries and rosemary.

Heat the cream to boiling, remove from heat and add vanilla. Heat about an inch of water in a saucepan and place a bowl over the top. The bowl should be large enough to seal in the steam, the base of the bowl should not be touching the water. Put the eggs and sugar into the bowl and whisk until thickened. Mix into the hot cream.

Mix the calcium lactate with a tablespoon of water in a small bowl. Microwave and stir until dissolved. Mix into the custard.

If the custard needs thickening sprinkle a pinch of xanthum gum over the custard and whisk in. Use only a tiny amount and leave to thicken – it will thicken more on cooling so do not add too much.

Allow to cool then place spoonfuls of custard into the alginate bath for 2 minutes.  The longer you leave it the thicker the gel membrane becomes.

Remove from the alginate bath and place in a bowl of water to rinse.  Before serving put sphericals in a bowl of hot water to heat the custard.

Serve with a circle of sponge cake, chopped strawberries and a sprinkle of rosemary.

Because the alginate gel is heat stable you can try baking it inside cakes – I experimented with this but found that they tended to burst during cooking.

Resource: howtocookthat