Ice cream is a colloid which is a type of emulsion. An
emulsion is a mixture of things that just won’t mix.
I know that doesn’t sound like it makes much sense
so let me explain.
Ice cream is a mixture of several ingredients. Two
of these ingredients don’t want to cooperate on a
molecular level. Can you guess what ingredients
I’m talking about? Yep, you guessed it, water and
fat. The fat in the cream doesn’t want to mix with
water. The fat and air bubbles in ice cream are
suspended in a matrix of tiny ice crystals.
Emulsifiers such as xanthenes gum and guar gum
are used by commercial brands of ice cream to help
bind the fats with the water, sugar, air bubbles and
ice. Egg yolks are the traditional ice cream emulsifier
which is what I use in my chocolate ice cream recipe
below. Egg yolks do something that other emulsifiers
don’t do – they add richness and flavor.
Making Ice Cream Without A Machine
1. Prepare your ice cream mixture, then chill it over an ice bath.
2. Put a deep baking dish, or bowl made of plastic, stainless
steel or something durable in the freezer, and pour your custard
mixture into it.
3. After forty-five minutes, open the door and check it.
As it starts to freeze near the edges, remove it from the freezer
and stir it vigorously with a spatula or whisk. Really beat it up
and break up any frozen sections. Return to freezer.
4. Continue to check the mixture every 30 minutes, stirring
vigorously as it’s freezing. If you have one, you can use a hand-held
mixer for best results, or use a stick-blender or hand-held mixer.
But since we’re going low-tech here, you can also use just a spatula
or a sturdy whisk along with some modest physical effort.
5. Keep checking periodically and stirring while it freezes (by hand
or with the electric mixer) until the ice cream is frozen. It will likely
take 2-3 hours to be ready.
You can easily make Stracciatella ice cream with Italian-style chocolate chips:
Drizzle pure melted dark or milk chocolate (about 5 ounces, 140 g) over the
almost-frozen mixture, then stir, breaking up the ribbons of chocolate as
they start to freeze, to create little ‘chips’.