By Harold McGee
Cream can be foamed by several different methods. Whisking by hand takes more time and physical exertion than an electric beater, but incorporates more air and produces a greater volume. The lightest, fluffiest whipped cream is produced with the help of pressurized gas, usually nitrous oxide (N2O). The most familiar gas-powered device is the aerosol can, which contains a pressurized mixture of ultrapasteurized cream and dissolved gas. When the nozzle is opened and the mixture released, the gas expands instantly and explodes the cream into a very light froth. There is also a device that aerates ordinary fresh cream with a replaceable canister of nitrous oxide, which is released in the nozzle and causes great turbulence as it mixes with the cream.