Ice cream, fro yo, sherbet, sorbet, granita… I will go for whatever Frozen dessert is available to me on a hot summer day like today.
Welcome back to another episode of food science Fridays. Today we’re making sorbet… well, sort of.
Different Types of Frozen desserts
I recently got a request to make a healthy dessert, and given that it’s hot out, my mind immediately jumped to ice cream.
Healthy is not a very descriptive term, and can mean different things to different people, but when I think about healthy I think about adding fruits and vegetables. Now there’s nice cream, which is basically a kind of frozen smoothie bowl made from frozen bananas which tastes a lot like ice cream, but I really wanted to make something different with the fresh fruit I had lying around. So instead, we are going to make a kind of peach sorbet.
I’ve always considered sherbet and sorbet to be types of ice cream, but they’re actually not. These frozen desserts have a have an iced fruit or fruit juice base, making their fat content much lower than ice cream. Sherbet is made with egg whites or gelatin and contains less than 2% milk fat, and often has more sugar than ice cream. Sorbet on the other hand is typically made without fat, eggs, gelatin, or dairy. By law, in the US, ice cream must contain at least 10% milk fat
But first, let’s talk structure!
The Structure & Texture of Frozen Desserts
The texture of frozen desserts depends largely on the crystallization of the water in the dessert. Crystals are formed upon freezing when the water molecules align, resulting in polyhedral structures we call crystals. The structure of ice cream is really a foam of air bubbles trapped in a frozen liquid. Anyways, I’ll discuss the structure specific to ice cream in greater detail when I do a full ice cream episode, but today I’m making peach frozen yogurt.
The texture of all frozen desserts depends on the size of the ice crystals that form during freezing. The smaller the crystals, the smoother and creamier the texture. In fact the water crystals in should be so small that we cannot feel them on an individual level.
So, basically, to make a good frozen dessert, we need to do our best to disrupt formation of large crystals, and luckily we know how!
A standard ice cream maker will churn air into the ice cream as it freezes avoiding large crystal formation. Instead, we are going to use a food processor to basically “churn” our frozen dessert after its been frozen.
Also, fat globules obstruct the growth of ice crystals which can slow the rate of recrystallization during storage & also lubricate the palate helping us perceive a smoother texture.
Results
Crystals look okay, but without added sugar, the dessert has frozen solid. Next week, we’ll be back to talk about freezing point depression.
Sources:
Brown, A. (2014). Understanding Food: Principles and Preparation. United States: Cengage Learning.