Have you ever wondered what the difference is between soft-serve and hard-serve ice cream (other than the obvious soft vs hard)? It seems as if outdoor ice cream stands only sell soft-serve ice cream, while supermarkets and ice cream shops tend to sell hard-serve ice cream. And if both are ice cream, why is one soft enough to lick with your tongue while the other is hard enough to require metal ice cream scoopers?
Both choices are delicious, so what’s the difference?
Ice cream can be categorized as different types of colloids. It is an emulsion, which is when both the dispersed substance and the dispersing medium is liquid. Molecules of fat are suspended in a water-sugar-ice structure. Hard-serve ice cream is generally more of an emulsion than is soft-serve ice cream because it has many more dissolved substances. For example, hard-serve ice cream has 10 to 18% fat content while soft-serve only has 3 to 6%. It is also a foam, which is when the dispersed substance is gas while the dispersing medium is liquid. The most important foam property of ice cream is the air content. Soft-serve ice cream is much lighter and softer than hard-serve ice cream because its air content is significantly higher.
Soft-serve ice cream is much more convenient when you’re on-the-go since it melts very fast, due to the high air content, so that you can eat it quickly. Hard-serve ice cream, on the other hand, can hold those small bits of dried fruit or chocolate to make this more expensive option even tastier! There’s no clear winner on which to choose, so we’ll leave it up to you depending on the occasion (:
Author: Jonathan Yu
Food Composition and Taste 