Ice Cream Science 101: Part 1

Welcome to my first blog post about ice cream! In this post, I will discuss some scientific properties of ice cream, as well as the benefits of using an ice cream machine. You also may get the opportunity to hear some weird/awesome music that I enjoy 😉

Without further adieu…

Dude, why do you even care about making ice cream, just eat the stuff!?!?

Since I started scooping ice cream at a locally-owned, gourmet ice cream shop a few weeks ago, I’ve had a strong desire to attempt to make the stuff myself. When I first started work, the whole process of making ice cream seemed so mystical – everyone was always so amazed by the quality of the product that the shop produced, always wondering how ice cream could possibly be so good. A few weeks in, I began to think that maybe I can give this a try for myself. But the major caveat is that, being broke, I don’t have any of the major kitchen tools that the shop has, such as a stand mixer or an ice cream machine. However, I then remembered that people have been making ice cream by hand for many years, since long before the invention of the ice cream machine – so there must be plenty of information online about how to do so.

But before I get into that, let’s get into the nitty-gritty about how ice cream machines (and ice cream itself) works.

How do ice cream machines work, and why do we use them?

In general, we use machines in order to conveniently automate tasks that are otherwise repetitive and time-consuming. Additionally, machines can have the ability to reproduce actions with a consistent level of precision and efficiency that is simply super-human. We humans are not robots, despite what Kraftwerk might have said in their song, “The Robots”:

Man, I probably just lost at least 10% of you guys with that weird (but still awesome) video…

Anyways, when it comes to ice cream production, ice cream machines live up to both of these points. But what are these machines actually doing that us mere humans would otherwise struggle to do?

To answer these questions, we need to dig just a little bit into the science of ice cream!

Ice Cream Science: 101

[Attribution: I learned much of the information in the following sections from the Ice Cream Science blog, as well as by reading many many recipes]

Making ice cream, as with making any kind of food really, is essentially a demonstration of chemistry in action. With ice cream, you’re mixing together seemingly disparate elements such as fats, sugars, water, and air, and somehow the end result is this amazingly creamy textured treat that most people love. But in order to get that creamy texture (rather than just a block of ice that tastes like ice cream), making ice cream involves the careful control of the following components: ice crystals, air cells, and fat/sugar cells. Let’s look at these components in a little more detail one-by-one…

Ice crystals play probably the largest role in determining the structure and texture of ice cream. The basic goal is to form many ice crystals that are all extremely small, since large ice crystals give ice cream a very icy texture. You also want these crystals to stay small after the ice cream has been put in the freezer for a long time. Ice crystal size is controlled by a number of factors, including the overall temperature of the ice cream mix during churning (the colder the better), the ability of your ice cream machine to absorb heat from the ice cream mix, as well as the amount of fat/sugar that is present in the mix (fat molecules actually replace water in the mix and arrange themselves in between ice crystals – more about that later). Ice cream machines distribute these tiny ice crystals during the churning process: an instrument called a “dasher” spins some of the ice cream from the center of the mix to the wall of the mixing bowl, the super-cold temperature of the bowl then causes tiny ice crystals to form, and an instrument called a “scraper” peels these crystals from the side of the bowl and reintroduces them back into the center of the ice cream mix where they can live happily ever after. These ice crystals then start to grow when the ice cream is placed in the freezer, but their growth will be insignificant to the ice cream’s overall texture if they are small enough to begin with.

Man, I know that’s a lot of factual information, but please bear with me because in the next post I will discuss my very own ice cream experiment and where it went right/wrong (spoiler alert: my ice cream was really tasty, but also a bit icy).

The amount of air present in an ice cream is probably the biggest factor that separates gourmet and commercial ice creams. Did you know that most store-bought commercial ice creams are essentially 50% ice cream and 50% air? You’re eating air, dudes! If you weigh both a scoop of commercial ice cream and a scoop from your local gourmet ice cream parlor, the local one is most likely to be heavier because it is made to contain far less air (usually between 10-20%). This is also why you might easily down a pint of commercial ice cream, but you would struggle to do the same with a higher quality ice cream. The economic reasons for a commercial ice cream producer to do this are obvious: air takes up space in the ice cream, and air is free, so they can make ice cream that takes up more volume in its container without actually using up more of the real-but-costly ingredients (like cream/sugar/vanilla/mixins). Plus people will eat more and more and more of it and never really feel full – its a win/win situation for them.

Before you get too pissed off at those greedy, crony-capitalist ice cream conglomerate bastards that are ruining America, it is important to realize that the presence of air cells is absolutely essential to ice cream. Ice cream without air would essentially be a frozen block of ice, since air provides insulation that prevents large ice crystals from forming a huge army and taking over your ice cream. As you may already know, we can introduce air into the ice cream mix by the process of churning/whipping. This is what goes on in your ice cream maker when you turn it on – an instrument called a “dasher” constantly rotates around in the ice cream mix, whipping the ice cream against the side of the mixing bowl and introducing air cells into the mix.

Music Break: Phew, that was rough. If you’re a little fatigued by all these facts, take a break and check out this classic album by electronic musicians Air:

The third major component that makes ice cream so delicious and creamy is fat/sugar. The fat is typically provided by either cream (high fat) or milk (lower fat). In order for ice cream to legally call itself as such in the United States, it must have a fat content of at least 10% – but gourmet ice cream often contains even more fat than that. As I briefly stated earlier, fat is super important to the ice cream’s structure because fat molecules can replace water in the mix and arrange themselves between ice crystals. Sugar is not just used for sweetening the ice cream, but it also plays a key role in the structure of the ice cream. Just like fat, sugar arranges itself between large ice crystals.

Anyways, there’s plenty more ice cream science to be discussed (more to come on this here blog) but the whole point of introducing you to the basic science was to make a point about ice cream machines and the ways they make ice cream production easier/better for us.

To recap, here are the important points about ice cream machines:

  • they keep the ice cream mix super cold, which enables the formation of ice crystals
  • they efficiently prevent the formation of ice crystals that are too large by constantly moving around tiny ice crystals between the wall of the bowl and the center of the ice cream mix
  • they are really good at churning and introducing air into the ice cream mix, which is essential to its eventual structure

That’s all that I’ve got for this post, but STAY TUNED for the next post in which I will tell you all about my experiment with making ice cream by hand for the first time!

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