Why isn’t ice cream rock hard?
When you take a steak out of the freezer, it’s as hard as a rock. But ice cream isn’t – why is that? Sugar and the freezing process are the secret to light, creamy ice cream.
“Ice cream is more than just frozen water, and it’s churned”. That would probably be many people’s answer to why ice cream doesn’t come out of the freezer as hard as ice. Right! But there’s more to it than that. The main ingredients of ice cream are cream and sugar – and not only because that’s a delicious combination.
Sugar makes the ice cream soft
Let’s talk about salt for a moment. In winter, when you want to make sure your driveway doesn’t get icy, you use salt. This is because salt considerably reduces the temperature at which water freezes. So instead of your driveway getting icy at zero degrees centigrade, it will stay ice-free.
The same principle is at work in ice cream, but we use sugar instead of salt because it’s much tastier. As the ice cream mixture is cooled down, some of the water freezes and forms ice crystals. The concentration of sugar increases in the rest of the water, lowering the freezing point of the sugar-water solution – just like the salt in the example above. As a result, the ice cream stays soft.
Light, creamy ice cream made in cylinders
But that’s not all there is to it. The way the ice cream is frozen matters too. We do this in horizontal cylinders, which are cooled from the outside. During the freezing process, the ice crystals that build up are scraped from the cylinder walls.
This stops the ice crystals from growing too big and giving the ice cream a sand-like texture. We can also whip in extra air, which makes the ice cream even lighter and creamier.
What’s more, our ice cream keeps very well at a temperature of at least -18°C. Many ice boxes in refrigerators cannot maintain this low temperature.
This causes ice crystals to grow, which you can not only feel with your tongue when eating the ice cream, but also see on the surface of the ice cream. So the quicker you polish the ice cream off, the better.