Evaporation. Conduction. Browning. And the science of deep frying.
Sizzling hot on the outside but freezing-cold ice cream on the inside! These extremes of deep fried ice cream are a great example of the science of deep frying.
Deep fried ice cream recipes usually call for scoops of frozen ice cream to be coated with egg white, and any combination of corn flakes, cookie crumbs, cereal or batter of some form. The coated ice cream is then frozen again. It is then deep fried briefly and taken out once the external coating turns into a golden brown crust. See the video below for a quick guide on this process.
The most surprising food-nomenon is how the ice cream remains cold — in fact almost frozen — despite the sizzling hot oil and crust. There are three reasons for this:
1) Evaporation: Once the coated ice cream comes into contact with the hot oil, any water found in it (e.g. the egg white, batter) evaporates and escapes from the surface of the food as steam. Steam pushes against the hot oil, preventing any of it from pushing into the food.
2) Conduction: As a result, the hot oil never touches the ice cream inside, and the only way the ice cream can be cooked is via heat conduction (read about heat conduction in the 1-Minute NomNom “Pleased to heat you!“) from the coating. This takes time, and because we are deep frying it briefly, the inside never reaches anywhere close to the high temperatures outside.
3) Browning: Once all the water has evaporated, the temperature begins to rise. The amino acids, protein and sugars in the coating undergo the Maillard reaction and caramelization. These are called non-enzymatic browning, and they seal the crust, further preventing any penetration of the oil, and leaving conduction as the only heat transfer mechanism. This is a slow process, so if we eat the deep fried ice cream soon after, the insides will still be ice cream-cold.
In many ways, deep fried ice cream perfectly illustrates the science of deep frying. It is the same process for other types of deep fried foods such as (click on the links for the 1-Minute NomNoms) beer-battered fish and chips, tempura, chicken/buffalo wings, donuts and french fries. The only main differences are what’s in the batter and the amount of time we leave it in the hot frying oil, which then determines the amount of browning on the outside and how much the insides are cooked.
Like this? Get the scoop daily by liking me to discover more! All you need is a minute a day to explore the world’s marvels through the phenomenon of food!
photos: in order – deposit photos/rakratchada; saaaaa; nupix