Science at home: Ice cream

Summer is here again, which is a great excuse to eat ice cream!

It’s not clear where ice cream originated.  Between 500 and 200 BCE early versions of ice desserts were eaten in various places.  Iranians combined finely ground ice with spices and fruits, ancient Greeks mixed snow with honey and fruit, and in China snow was mixed with milk and rice. In the 1500’s CE, Europe’s royalty and upper classes enjoyed ice cream, but because it was very expensive (due to sourcing ice and keeping it cold), most people didn’t have a chance to sample it.

1800s English celebrity cook and culinary entrepreneur Agnes Marshall (aka ‘Queen of Ices’) was a key player in popularising ice cream, resulting in large amounts of ice being imported from Norway to London. She is credited with creating the recipe for the first ice cream cone. She patented an ice cream maker that could produce about 500ml of ice cream in just 5 minutes, all without modern refrigeration! Agnes even suggested making ice cream using liquid nitrogen – a method still used today. The advantage of using liquid nitrogen is that it freezes the cream very quickly, so the particles stay very small (freezing things more slowly allows larger crystals to form), and the liquid nitrogen aerates the cream. This all makes a very light and creamy ice cream.

Since most of us don’t have easy access to liquid nitrogen, its lucky most shops and homes now have freezers, allowing us to enjoy ice cream any time we like! And while some of us have traditional favourites, you can get all kinds of ice cream flavours around the world – from cow tongue or squid in Japanbrown bread in Ireland and cheeseburger in Venezuela. Or if you’re a fan of the sweet and salty combination of salted caramel, you might like the sound of pear and blue cheese ice cream from the USA!

Try your own mix at home! If you don’t have an ice cream maker, you can follow a similar method to the one used in the 1700s – using salt and ice to cool cream to well below zero.  This recipe is a good primer. Dissolving salt in the ice lowers its temperature (it’s what we call an endothermic reaction), your cream will turn into ice cream quicker! You can experiment with different flavours, quantities of ingredients, or see if changing the salt content makes the process faster or slower.

If you’re interested in being involved with food as a career, you might want to check out our Biotechnology or Nutrition and Dietetics degrees.

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