How To: Making Ice Cream
How To: Making Ice Cream
Dr. Gareth Francis shows a simple scientific way of making an ice cream at home without a freezer. That way, you can design your own ice cream adding different colors and flavors.
Today, we are going to make ice cream without a freezer. So, we are going to make it on a table and it's going to freeze, and this is ideal for children because you can just make it with them and then leave it for ten - twenty minutes and then they can eat their own ice cream. And they can design their own ice cream - whatever color they want, whatever flavor they want and they can see it freeze and everything together.
So it's really good. What you need to make is you will need a metal bowl, and it's metal because you need it to conduct heat through it or conduct heat away from it to freeze the ice cream. You will need a plastic bowl which you are going to put your metal bowl inside and you are going to fill that with ice.
You will need some cream to make the ice cream out, because ice cream is essentially cream, double cream, you can also add some milk to it if you want, to make it a bit less thick. You will need some sugar to flavor it and you'll need some nice food coloring and some nice flavoring. So I've got strawberry flavoring and I've got red food coloring today.
And also, you will need some salt, quite a lot of salt, actually. Now, this is the science bit – salt. What it does is when you put it on the ice, it depresses the freezing point of ice, so it makes it lower.
And that's actually why we put salt on the road in the winter because if you can decrease the temperature which ice freezes, then it won't freeze at minus one, minus two, won't freeze till it's up to minus six, so you will get less ice on the roads. This is the similar effect and when you put ice, salt in the ice, it makes the ice really, really cold, and you will see when it all freezes together and sticks together. It gets so cold that it is able to freeze the cream.
So, start with some cream and a milk, that's all ice really is, just cream. Then we'll add some sugar, spoonful of sugar for a bit of flavor, we are going to add some food coloring, could be any flavor you want and a bit of color as well - this is the fun bit little kids love - couple of drops of red food coloring, give it a stir, keep adding it till it gets to the color you wanted to be. You can add more different colors, you can add blue colors and yellow colors to it, and you can add different flavors as well, but I would advise you to not add too many colors and flavors in because it will taste horrible and also it takes longer to freeze.
Now, we are going to do the freezing part, so I'm going to get some ice, some broken up bits of the ice, crushed ice. We are going to put that into our plastic container, so you need enough so it surrounds the metal pot and makes a good contact with because is going to sucking out the heat out of that to freeze the ice cream. So, now, it won't work without a salt, so you will need to add lots of salt which depresses the freezing point of the ice.
So you will think you are putting too much salt in but you're not, just put loads of salt in, like that, and then we just put the ice cream inside. You'll see that it's actually going really quite cold and start sticking together because of the salt. So you got the ice touching all around the metal, add top like that, give it a stir, and then put the lid on so that no heat gets into it and then you leave it for about ten or fifteen minutes.
Right, after about ten or fifteen minutes, open the ice cream up and just lift it up, you can see it has started to get pretty solid. That's some ice cream, try that, strawberry. That's the way you make ice cream without the freezer. .