Yet another culinary technique popularised by modernist chef Ferran Adrià, espuma (the Spanish word for foam or froth) is now widespread on fine-dining menus – to the point where it has come to be seen as a little passé. While critics often view foams as over-fussy, unnecessary and somewhat outdated, in fact, the technique has been used for centuries; cappuccino, anyone? Moreover, when harnessed appropriately, foams can add wonderful textural nuance to a dish – and textural nuance should always be encouraged when it comes to creating multi-layered, interesting food.

Essentially, foams are just aerated liquids; and their density will depend on the thickness of the liquid and the ratio of liquid to air. A lighter foam may be more accurately described as froth – such as the head of a beer or cappuccino – while a denser foam will resemble mousse. But whether you are striving for froth, mousse, foam or even ‘air’, the methods are likely to be similar.

Though it is possible to create foams without the use of artificial stabilisers (as with eggs, milk, butter etc.), the introduction of ingredients such as lecithin – brought to prominence by Adrià in the 1990s – paved the way for chefs to ‘jush-up’ less-stable liquids (stocks, sauces, juices etc.). Lecithin works in a similar way to the proteins in egg and milk – acting as an emulsifier to hold the shape of the foam – and the amount you disperse into the liquid should depend on how stiff you want it to be. Whether using lecithin or alternatives such as agar agar, gellan gum and gelatine, though, it is important to note that for a liquid to translate into a foam it must contain elements of either lecithin, monoglycerides (emulsifying fats) or protein.