Compare: eat a popsicle, scoop it offvanilla ice cream, and a slice of semifreddo. They are very different in structure. An ice cream stick is hard, a scoop of vanilla ice cream is softer and scoopable, a semifreddo is even lighter and airier.
One of the main differences between these types of ice is the amount of air they contain. Yes, air, much like the air around you. Many ice cream styles contain air. Air is essential to create a lot of ice cream, but it also ensures that the ice cream tastes warmer. Does that sound contradictory? We have to explain it all.
Air + Is
- It is not without reason that your ice cream pints consist of 50% air
- Air improves scoopability
- Air insulates your tongue
- How to incorporate air into ice cream
- Beat cream or eggs
- Continue learning
It is not without reason that your ice cream pints consist of 50% air
The next time you buy a carton of ice cream, weigh it. Eat it and fill the packet with the same amount of water. Most likely, your ice pack filled with water is much heavier than the same pack filled with ice.
Why? Because most ice contains a lot of air. With store-bought ice cream, half of the ice cream's volume can be air. Therefore, a 1 liter box of ice may only weigh 500 grams, while the same box filled with ice weighs 1000 grams when filled with water.
Yes, ice cream machines literally sell you air. But they don't just do it to save money, since air is cheap. Air plays some very useful and crucial roles in ice.
Air improves scoopability
Have you ever tried to scoop a popsicle? Probably not, they are often too difficult to create. One of the reasons popsicles are difficult to scoop is their lack of air. They are essentially dense frozen sugar solutions full of ice crystals. Scooping into an ice crystal is very difficult. However, scooping it through an air bubble is not that difficult. If your ice cream has a lot of small air bubbles spread throughout the ice cream, it will be much easier to scoop through.
Air insulates your tongue
Some ice creams just feel much colder when you eat them than others. Even though they both come from the exact same freezer. Compare crunching a solid ice cube in your mouth to a scoop of gelato. Air also plays a key role here.
Frozen ice contains many ice crystals. When these ice crystals hit your tongue, they melt. To do this, they extract heat from their environment, causing you to feel the cold. If your entire tongue was covered in a slippery layer of ice crystals, it would be quite cold. But if that skin contains a lot of air bubbles, not all those ice crystals will be able to touch your tongue. Instead, the air acts as an insulating layer between your tongue and the ice.
Air bubbles serve as an insulator, making an ice cream appear less cold.
How to incorporate air into ice cream
Air certainly has a purpose, but how do you incorporate it into your ice cream? You can do this in a number of ways:
- Add air to oneingredientthat can hold the air well
- Heavy cream
- No
- Introduce airduring freezingthe ice
Beat cream or eggs
Beat some cream or eggs and within a few minutes you will have a light and airy foam. Both ingredients are good at trapping air when you push air into them with a whisk or mixer. Simply add the other ingredients and you have an ice cream base, ready to be frozen.
In cream, it is the fat molecules that ensure that it retains air well. The fats organize themselves around the air bubbles and stabilize them. We use it to make a simple one2-Entering. In the case of eggs, it is the proteins that excel at retaining air bubbles. We use them to create a light and airy atmospheresemifreddo.
However, cream or eggs can trap air forever. Over time they will slowly collapse, deflate, into a puddle. But that is not necessary. When the ice is frozen, it becomes so firm that the air bubbles stay in place.
Freeze and mix
It is not always possible to use an ingredient to trap the air. Additionally, ice cream made this way is slightly less stable over time. You can't keep them for that long.
In these cases, you will need to use air while freezing the ice cream. As it freezes, the ice solidifies, making it harder for air to escape. There is a sweet spot during this process where the ice cream is not yet too firm to mix, but firm enough to hold air.
This is what ice cream makers do in a process called churning. The machine freezes and mixes the ice cream at the same time. If you don't have an ice cream maker, you can also do this by freezing an ice cube tray and taking it out of the freezer occasionally, stirring it to get air in it.
In ice cream factories they use more advanced equipment, but the principles are basically the same as those you use at home. Learn more aboutfactory production here.
Thicker ice bottoms = more air?
Custard-based ice creamis a type of ice cream in which you first make a thickened custard, which you then churn. One of the reasons an ice cream base like this works so well is that it expandsviscosity(it's thicker), it helps trap air while kneading.
Continue learning
Air is just one of the components that make your ice cream a success. Do you want to learn everything about the science of ice? Why don't we get ours?4 week ice course? Not ready for a course yet, browse oursice archives. I would suggest learning more about itfreezing point depressionof die enerole of emulsifierFollowing!
