The increase in volume of the whipped cream foam due to the trapped air is called overrun, a term often used when making ice cream. A high‐fat cream will create a stiff foam capable of trapping a large volume of air bubbles; therefore, the higher the content of fat in the cream, the thicker the whipped cream and the greater the overrun or increase in volume. Thus, or country creams with more than 36% total fat will allow for a stiffer, higher‐volume cream, and a low‐fat cream such as light cream will have a thinner, liquid‐like whipped cream consistency. The UHT pasteurized creams are difficult to foam because of the chemical changes that occur in the milk fat globule membrane and proteins during pasteurization. Foaming a UHT pasteurized cream requires the addition of surface‐active agents and stabilizers such as whey or gelatin proteins or complex carbohydrates such as gums to provide the needed additional support.
So why do most whipped cream recipes direct you to use chilled cream and a cold bowl? Once the milk fat globule membrane is torn and the fat droplet is exposed, the exposed fat needs to remain solid to maintain the cage around the air bubbles. Like any other fat, once the material warms enough, the fat turns to liquid oil, the cage collapses, and the oil coalesces into a solid mass, giving the overwhipped or warmed foam a greasy, buttery feel to the tongue.
Foams Imagine a latte or cappuccino and the milk foam sitting on top. The foam can make or break your drinking experience. In this context, the foam is made of denatured proteins that form a thin protein film holding small air bubbles in place. In the case of milk foams, the milk is “steamed” into a foam by forcefully bubbling hot steam into the milk. The whey proteins are denatured by the heat of steam and the physical agitation of mixing with the heated water vapor and air.