Serving cocktails with a foam might seem like trying to make from an average cocktail slightly more interesting one but it doesn’t necessarily has to be that way. When used right it can add a pleasant texture, interesting flavour to your palate and incredible visual appeal.
In order to make a foam you need a fat(emulsifier) and stabilizer without one or another it would make for a poor results. Foams can appear in a different styles depending on stabilizer used and different techniques such as whisking, blending but far the easiest and the most effective way to create foams is to use Cream Whipper.
Cream Whippers work by forcing nitrous oxide(N2O) into the liquid to be whipped. Firstly intended liquid is poured into the Cream Whipper then lid is tighten. The vessel is then charged with 8g N2O Cartridges. This increases the pressure inside the vessel and force nitrous oxide to dissolve into the liquid. When liquid is dispensed through the nozzle it suddenly reaches atmospheric pressure and the dissolved bubbles expend, creating light, aerated foam. Cream Whipper can be prepared and chilled hours before and is able to extend the shelf life of liquid for couple of days.
When we talk about chemical reactions which are closely related to a foam making then dispersion means that there are evenly-spread materials mixed into liquid. Liquid in liquid dispersions(vinaigrette) are emulsions. Solid in liquid dispersions(coffee) are suspensions. Gas in liquid dispersions are foams. Another word for foams used mostly in the world of cooking Espuma (which is foam in Spanish) or Airs which are extremely light foams.
Stabilizing the foam
The most traditional ingredients such as Egg White or Cream can be effectively used to create stable foams but there are other things which influence the result of the final product such as level of acidity, alcohol and fat in the intended liquid which was supposed to be whipped. So the most gelling/thickening agents can be used as a stabilizer as long as the liquid is in operating range.
The best results for the most stable foam with silky soft texture calls for Egg White Powder(Albumin) which doesn’t require to be heated and Gelatine sheets which need to be soaked first in a water then heated with a liquid to 60 °C, cooled and added to Cream Whipper.
Other gelling/thickening agents which can be used to create foams such as Agar-Agar and Gellan gum which requires liquid to be heated first so they can be dispersed but there are quite heat stable so they can be served in a warm drinks.
Xantham Gum doesn’t require liquid to be heated first and works very well as a thickener to stabilize the foams.
Iota Carrageenan works very well with dairy and creates soft foam in the presence of calcium.
I was experimenting with Almond flavoured foam and cocktail called Nutty Gingerbread. For Almond Foam you need following ingredients: 1 1/2 Gelatine sheet, 40oml mineral water, 90ml Orgeat Syrup, 5ml Hazelnut Flavour Drop, 15g Albumin
Add Gelatine, Orgeat Syrup and Hazelnut Flavour Drop to mineral water then heat it up until Gelatine dissolves then add Albumin and transfer the mixture into Cream Whipper, charge with 1 cartridge nitrous oxide, shake and refrigerate for at least 2 hours.