Your Shortcut to… Ice Cream

LINKS:
Ice cream in a bag: https://www.delish.com/cooking/recipe-ideas/recipes/a54721/ice-cream-in-a-bag-recipe/
Liquid nitrogen: Turn your breath to a solid – http://www.stevespanglerscience.com/experiment/00000114
Liquid nitrogen: Shatter flowers: https://www.youtube.com/watch?v=Gz3lrLoW0og
Liquid nitrogen: Make ice cream: https://www.thoughtco.com/make-liquid-nitrogen-ice-cream-606309

EPISODE TRANSCRIPT
Australians eat 20 litres of it per year … it wouldn’t be possible without science … and there are some seriously weird flavours. This is your Squiz Kids Shortcut to Ice Cream—the podcast where we dive into the who, what, when, where, why and how of the big news stories. I’m Amanda Bower.

And I’m Bryce Corbett.

It’s almost summer! Which means it’s almost summer holidays… which means it’s almost time for our days to be filled with swimming, and playing outside, and… EATING ICE CREAM. One of the best foods on our planet, if you ask me.

Today, we’ll take you through WHEN ice cream was invented… HOW science helps us make it even more delicious … and WHAT are the freakiest flavours

Listen carefully – there’s a Squiz at the end!

WHEN
Bryce, long before freezers were a thing, snow and ice were prized ingredients in dessert making.  Ancient Egyptian hieroglyphs show a snow-filled vessel next to fruit juice…. Recipes for snow-chilled sweets are included in a 1st-century Roman recipe book…. And there are Chinese Tang dynasty records from 1,500 years ago of a chilled dessert made with flour, camphor and water buffalo milk … And in India in the sixteenth century, the Mughal Empire used relays of horsemen to bring ice from the Hindu Kush to the capital, Delhi, to make kulfi, a popular frozen dairy dessert that is still often described as “Indian ice cream.”

Horsemen riding with ice that they cut from a cold place, and transported to a hot one… wow! So much more complicated than it is now.

For hundreds of years, frozen desserts were a huge luxury! It wasn’t until after 1926, when the technology for commercial freezers was perfected, that the modern ice cream industry was born. We went from using a hand crank to stir the cream and flavouring over a bed of salt and ice… to popping down the shops and picking up a tub.

Wait a second… ice and salt? What does salt have to do with ice cream?

Ah, that’s what we call and endothermic reaction – and without it, no one ever could have used milk and cream to make a frozen dessert.

Sounds like you need to tell me HOW science helps…

HOW

Alright, so the ingredients of your typical vanilla ice cream are: milk, cream, sugar, vanilla, of course, and …  air.

AIR?

Yup! Air makes up anywhere from 30 to 50% of your typical ice cream. One way to think about the effect of air on ice cream is to compare in your mind the flavour of whipped cream, to the flavour of runny cream. Adding air – which is what whipping does – changes the structure of the ice cream, and the larger the structure, the longer it takes for the flavour molecules to be released into your mouth. Put it this way… if you’ve ever had ice cream melt and then refreeze, it takes up less space in the container, and it’s less yummy. Right?

That is definitely true. And where does the salt come in?

Well, water freezes at zero degrees Celsius, right?

Right.

But when you have a mixture of cream, milk, and sugar, the freezing point is LOWER. So to get our ice cream mix to freeze, we have to make the ice colder. Adding salt to ice lowers the freezing point of the ice, meaning that it melts faster… and when ice melts, it’s absorbing energy, in the form of heat, from the environment. So if a big bowl of cream and milk and vanilla is sitting on top of the ice, heat is drawn away from the ice cream mixture towards the ice. The ice melts, and the ice cream freezes.

And that’s an endothermic reaction?

Yep! Melting is endothermic, freezing is exothermic. You can see it for yourself if you pop some milk and sugar into a plastic bag, seal it tightly, and put that in a bag of ice with salt. Dance around like a crazy person for a few minutes , and you’ll have made ice cream. I’ll pop a link in your episode notes for that.
Of course, most people making ice cream at home nowadays have a machine that stirs the ice cream as it freezes… but my favourite home method is one developed by British and American pilots in WWII. They attached 5 gallon cans to their aircrafts, fitted them with a small propellor, and poured the ice cream mixture in before they took off. The slipstream spun the propellor, which drove a stirrer, and the intense cold of high altitude froze the mixture. They’d land, and have dessert.

Crumbs! That’s adventurous… I don’t recommend that Squiz Kids try that at home!

Indeed… no bombing runs thanks kids. But for those of you who are a bit adventurous, I’ve put a link in your episode notes on how to make liquid nitrogen ice cream.

Don’t doctors use liquid nitrogen to freeze warts?

They sure do! Liquid nitrogen is an amazing thing. Nitrogen is all around us as a gas, and it only becomes a liquid at -196 degrees. It has to be stored in a special container, and as soon as you pour it out, it basically boils off and becomes a gas. But if you pour it into ice cream mixture, while you’re stirring it, it freezes it so quickly that it is extra creamy and delicious. You’ll see in the link that I’ve also suggested some other VERY cool experiments you can do with liquid nitrogen, including turning your breath into a solid… and freezing and shattering flowers. It’s a ton of fun.

Those early ice cream lovers couldn’t have conceived of liquid nitrogen ice cream…. they didn’t even have freezers! WHAT other new freaky things are happening in the world of ice cream?

WHAT
Alrighty Bryce, when I googled “weird flavours of ice cream” I found the following three things. I want you to tell me what you think they have in common. Number one: a fish and chip flavoured ice cream that looks just like a plate of fish and chips… Number two: pizza flavoured ice cream with tomato, oregano, salt, garlic… Number three: a smoked salmon ice cream sandwich made for the occasion of Canada’s 150th birthday…

I’m pretty sure that what they all have in common is that they have no business being ice cream flavours.

People swore they were delicious! But no, that’s not it. Every single one of those ice cream makers is now out of business… which would suggest that they were also NOT delicious. However, Ben and Bills chocolate emporium in Maine has been serving buttery lobster ice cream since 1988, and people swear by it. And Japan really is famous for flavours like Squid Ink, whitebait, wasabi and more…

Wasabi ice cream? Wasn’t it in the Cars 2 movie where Mater ate a pile of wasabi in Japan, thinking it was pistachio ice cream?

That’s the one. And now he could even be fooled by actual spicy green ice cream.

The S’Quiz
This is the part of the podcast where you get to test how well you’ve been listening…
1. In which country did a relay of horsemen ride ice to the capital to make frozen desserts?
2. What is the ingredient in ice cream that changes its structure to make it bigger and tastier?
3. If you had to choose between fish and chip flavoured ice cream; pizza flavour; or smoked salmon flavour… which would you choose?