Easy Ice Cream
One of my favourite food books is Americas Test Kitchen’s The Science of Good Cooking. The section on freezing shares many phrases with the steel manufacture section of my materials science books from engineering school. “Nucleation”, “crystal growth”, “supercooling”; steel and ice are very similar at the microscopic level.
But unlike steel and ice, we want ice cream to be soft. So when its made, we use whatever cheats we can to stop a solid, hard mass forming. Sugar not only sweetens, but forms a super slippery sugar solution between ice crystals. Air bubbles and fat molecules also help separate ice crystals, while a rapid freezing time ensures those crystals are as small as possible (see Kurt’s liquid nitrogen version). For more on the science of ice cream see Clarke, 2003, “The Physics of Ice Cream”
Americas Test Kitchen’s recipe for homemade chocolate ice cream applies these principals and uses only cream instead of a milk-cream mix: no churning required! My flat has no ice cream maker (three toasted sandwich presses though) so this was a revelation to me, and led to enthusiastic testing of new flavour bases: mint-chocolate, passionfruit, banana, peanut butter, boysenberry, pretty much anything in a two metre radius of my kitchen got turned into ice cream. Two months (and 4kg on the bathroom scales) later, the recipes below are mine and my tasters’ favourites. Feel free to apply the general idea and make up your own bases with your own favourite flavours, and let us know how it goes in the comments below!
Each version makes 1 litreChocolate Chili Lime Version
1 tsp instant coffee powder
3 tbsp hot water
100g 50% cocoa chocolate, broken into pieces
½ cup sweetened condensed milk
½ tsp vanilla extract
¼ tsp salt
½ tsp chili flakes
Juice and zest of one lime
1 ½ cup cream
Salted Caramel Version
This version is particularly good as you just need cream and a few pantry staples to make an awesome dessert.
1 cup sugar
1 ½ tsp salt
¼ cup + 2 tbsp hot water
1 ½ cup cream
MethodChocolate Chili Lime Version
1. Combine coffee powder and 1 tablespoon water in a mixing bowl. Add chocolate, condensed milk, salt and vanilla extract and microwave for 1 minute or until melted, stirring every 20 seconds.
2. Add remaining 2 tablespoons of water, lime ingredients and chili to a small saucepan. Bring to boil and simmer for 2 minutes. Add to chocolate mixture.
3. Whip cream to stiff peaks. Whisk one third of the cream into the chocolate mixture, then fold in the remaining cream until combined.
4. Pour into plastic or metal container, the flatter the better. Put your refrigerator into fast freeze if available, and freeze for at least 6 hours or up to 2 weeks. Serve.
Salted Caramel Version
1. Pour ¼ cup water, then sugar into center of medium sauce pan. Agitate to spread across bottom.
2. Heat over a medium high heat until first shades of brown start appearing. Remove from heat and swirl, return to a low heat until the colour of golden syrup.
3. Add butter and stir over a low heat until an even consistency
4. Dissolve salt in 2 tablespoons of hot water. Add to caramel mixture, again stirring over low heat until even. Some caramel may initially set but will remelt.
5. Give caramel 10 minutes to cool, whipping the cream to stiff peaks in the mean time. Whisk one third of the cream into the caramel mixture, then fold in the remaining cream until combined.
6. Pour into plastic or metal container, the flatter the better. Put your refrigerator into fast freeze if available, and freeze for at least 6 hours or up to 2 weeks. Serve.
For more on the science of ice cream see Clarke, 2003, "The Physics of Ice Cream"