If you shake cream and ice long enough, it turns into ice cream. Sweet! But just how much shaking, and for how long?
WHAT MAKES ICE CREAM CREAMY?
This ice cream is made of sugar, fat, ice crystals, and air. Ice cream’s creaminess depends on the size of the ice crystals that form during freezing — the more you shake, the smaller the ice crystals become and the more air is incorporated into the ice cream. Doing both makes for a creamier cream!
WHY DOES SHAKING SOME DAIRY IN A BAG MAKE ICE CREAM?
Ice cream is an emulsion, which means small droplets of one liquid dispersed or spread throughout another. Think salad dressing: Oil and vinegar don’t dissolve, but they can disperse into an emulsion with the help of a whisk. When you shake the bag, it emulsifies the ice cream, dispersing the ice crystals, fat molecules, and air.
Why salt? Salt lowers the melting temperature of the ice; the colder the icy solution around the ice cream, the faster the cream freezes.