Ice Cream Class

ChefSteps

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Ice Cream: A Parametric Analysis

The Infographic

Ice cream isn’t just frozen cream, as the name might suggest, but that’s pretty close. Ice cream is a sweetened, fat-in-water emulsion that’s aerated as it’s frozen. It can contain eggs, but they aren’t necessary, and the stuff at the store almost always contains scary-sounding stabilizers and emulsifiers (but they’re not spooky at all, we promise!).

Here’s a brief rundown of the main components of ice cream:

Water (ice): It’s right there in the name—ice is a key component of ice cream. Frozen water forms the bulk of the treat, and the size of those ice crystals determines how good it is, specifically its smoothness and creaminess. Teeny-tiny ice crystals? Super-smooth and creamy ice cream. Large ice crystals? Icy, grainy, and hard ice cream. (See below for more!)

Dairy: All ice cream contains dairy, whether that’s milk or cream (or some combination of both), other forms of dairy like yogurt and (yup, sometimes) cream cheese, or products like nonfat dry milk powder. (There are, of course, non-dairy “ice creams,” but that’s a topic for another day.) Dairy provides the water (which forms ice crystals), fat (which adds richness, flavor, and improves aeration), sugar (lactose, which sweetens and affects texture), and proteins (casein and whey, which act as emulsifiers).

Fat: You can’t have ice cream without fat; you’d just have ice. Fat in ice cream is what gives it flavor, richness, and allows it to be aerated, as tiny globules of fat freeze and stick together, forming networks that can trap air that’s incorporated into the base as it’s churned.

“Milk solids-not-fat” (MSNF): This ungainly term is what’s used in the industry to denote everything that dairy provides that isn’t fat—sugar (lactose), proteins (casein and whey), and salts.

Sugar: Ice cream has a lot of sugar! And it’s not just for sweetness! Sugar depresses the freezing point of the base; without it, ice cream would freeze up hard as an ice cube. Sugar also increases the total amount of solids in the base, which gives the ice cream body.

Egg yolks: A lot of ice creams are frozen custards—a mixture of egg yolks and dairy, cooked until thickened, then frozen and churned. Egg yolks provide richness to ice cream, since they’re mostly fat, but they also <a href="https://www.chefsteps.com/activities/cracking-the-egg-resource">contain lecithin</a>, which improves the ability of the ice cream base to trap air during churning.

Stabilizers: Stabilizers, such as guar gum, locust bean gum, and lambda carrageenan, primarily thicken the ice cream base and make it more viscous by binding excess water, which controls how water behaves after the ice cream has been frozen. 

Emulsifiers: When talking about emulsifiers in ice cream, we’re usually not referring to emulsifiers like casein, the primary emulsifier in dairy products. Usually, we&#39;re talking about added emulsifiers. The primary role they play is to disrupt the way casein molecules emulsify dairy products, and the goal is to encourage crystallization in the fat globules once the ice cream base is frozen, which in turn helps the ice cream hold onto incorporated air. 

Air: Ice cream is a foam, so air is a big part of it. The amount of air incorporated into an ice cream is referred to as “overrun,” and it is determinative of its quality (and price point), which should make intuitive sense. Add just enough air to make it creamy and soft and delicious? You’ve got great ice cream that you pay a premium for at the store. Add so much air that a pint is about 50% air? You’ve got “economy” ice cream that’s sold in large tubs at the supermarket.

The Elements of Ice Cream

The secret to great ice cream? Crystals. Teeny-tiny ice crystals, that is.

The smoothness and creaminess of ice cream is primarily a function of the size of its ice crystals. The secret to producing (and maintaining) small ice crystals in ice cream is getting it cold fast. Bringing the ice cream base rapidly down in temperature both creates tiny ice crystals and prevents the tiny crystals from growing while the ice cream churns and hardens.

Ice cream is traditionally made using a process called “dynamic freezing,” which basically means the base is churned while it’s being frozen.* In both commercial and at-home ice cream machines, containers of liquid ice cream base are chilled from the outside in, and the outermost parts of the base freeze against the container walls—the formation of ice crystals against the container walls is called “nucleation.” As the base freezes, a dasher churns it, scraping the frozen base off the sides of the container and pushing it into the center, where it melts, chilling the base in the center in the process.

When enough frozen base has moved to the center of the container and the base has dropped to below freezing temperatures, the ice crystals stop melting and start growing, combining with other ice crystals in a process called “ripening” or “recrystallization.” And this is where chilling and churning the base as fast as possible is super important: The longer the ice cream churns, the more recrystallization occurs, creating larger and larger ice crystals—and icier and icier ice cream as a result.

Freezing the ice cream base fast is just as important after it comes out of the churner. Even though the ice cream base is done churning, it’s still made up of a lot of liquid—that soft serve texture of just-churned ice cream is produced by the combination of frozen water (tiny ice crystals) and a concentrated sugar solution. (For more on this, see the section on “Sugars in Ice Cream” below.) To minimize recrystallization after churning, it’s important to get the ice cream into a freezer that can bring the temperature down low enough to ensure that it’s frozen solid.

The importance of freezing the ice cream base fast can’t be stressed enough, particularly since it’s the main reason why at-home ice cream makers produce icier ice cream than commercial machines—they just don’t have the freezing power!

But it also explains why the best way to churn ice cream at home is <a href="https://www.chefsteps.com/activities/liquid-nitrogen-churned-ice-cream">using a stand mixer with liquid nitrogen</a> or <a href="https://www.chefsteps.com/activities/making-ice-cream-with-dry-ice">dry ice</a>. Both substances are so cold ([f -320.4] and [f -109.3], respectively) that they freeze the ice cream base far more rapidly than a regular countertop ice cream machine.

*It’s important to note that the Pacojet and Ninja CREAMi don’t employ dynamic freezing for producing ice cream. Learn more about how these machines work in the tip below. 

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How to make ice cream with dry ice and a stand mixer.

How to Make Ice Cream With Dry Ice

How to make ice cream with liquid nitrogen in a stand mixer.

How to Make Ice Cream With Liquid Nitrogen

Ice Cream Is All About Ice

The Ice Creams

Classification: Low Fat

Sweetness:🍦🍦🍦🍦🍦

Flavor: Milky.

Texture/richness: Creamy, like denser soft-serve.

Recommended churning method: Countertop (conventional).

Ideal serve temp: [f 6] to [f 10]

This ice milk is refreshing, light, and sweet!

Don’t let the name fool you: It’s not icy at all. Unlike a sorbet or Italian ice, it’s surprisingly creamy, with an almost soft serve-like texture, but a little more dense, since it’s frozen to and served at a lower temperature.

The texture is a direct result of its sweetness. The lean formula relies entirely on milk for fat, so the sugar has been bumped up to make it softer than it would be otherwise. That also means that it melts fast.

The use of cornstarch as a stabilizer stands out; the other ice creams in this analysis that rely on stabilizers use a hydrocolloid mix of locust bean gum, guar gum, and lambda carageenan. When very, very cold, this ice milk has a texture that’s reminiscent of dondurma, the Turkish ice cream that has a distinct chewiness.

[link https://www.seriouseats.com/vanilla-ice-milk-recipe Ice Milk (Stella Parks, Serious Eats)]

Commonly used sugars: Granulated sugar (sucrose), lactose, invert sugar (glucose powder and fructose), glucose syrup, corn syrup, dextrose.

Freezing point depression: Sugar is a key ingredient in ice cream and not just because ice cream is sweet. Sugar is crucially important for ice cream’s distinctive texture: soft and scoopable, even when frozen nearly solid.

The reason ice cream isn’t hard as a block of ice is because it’s not just a solid—it’s a solid, a liquid, and a gas. And the liquid part is only made possible at freezing temperatures because the ice cream base is a concentrated sugar solution.

Sugar lowers the freezing point of water (this is called “freezing point depression”), and the more sugar that’s dissolved in water, the lower the freezing point will be. As ice cream is churned, available water is turned into ice, which increases the concentration of sugar in the remaining liquid ice cream base. As more and more water turns to ice, the sugar concentration in the remaining liquid becomes so high that it won’t freeze, even at temperatures well below the normal freezing point of water, which leaves you with a super-cold substance that is both solid and liquid—ice and a super-sweet solution—at the same time.

And not all sugars affect the freezing point in the same way. Lactose (the sugar in milk) depresses the freezing point by the same amount as granulated sugar (sucrose), but other sugars, such as invert sugar, glucose syrup, corn syrup, and dextrose, depress the freezing point further.

Sweetness: Ingredients like dextrose and glucose syrup taste less sweet than sucrose. This is one of the reasons why they are widely used in commercial ice cream production: They taste less sweet than granulated sugar and depress the freezing point more than sucrose, which allows you to make soft ice cream that isn’t overpoweringly sweet.

Sugar-free ice cream: Artificial sweeteners can be used to make sugar-free ice cream. We recommend using sugar alcohols, such as sorbitol or erythritol, since alcohol depresses the freezing point of water more than sucrose, and because they aren’t as sweet as other artificial sugars like aspartame.

Artificial sweeteners are often used in conjunction with fructose, as it has a lower glycemic index than sucrose.

Sugars in Ice Cream

Classification: Light

Sweetness: 🍦🍦🍦🍦

Flavor: Clean and clear vanilla.

Texture/richness: Light, creamy, and refreshing.

Recommended churning method: <a href="https://www.chefsteps.com/activities/liquid-nitrogen-churned-ice-cream">Liquid nitrogen</a> or <a href="https://www.chefsteps.com/activities/making-ice-cream-with-dry-ice">dry ice</a>.
 
Ideal serve temp: [f 18] to [f 20]

Soft serve is defined by its texture, and this ice cream hits the textural cues on all fronts: light, lean, and firm enough that you can lick it and it’ll still hold its shape. But it also starts melting quickly, since it’s served at a slightly higher temperature than most of the other ice creams in this analysis.

This ice cream is a little richer than the ice milk, but because it’s still lean, it’s got a fast but fleeting flavor release. The vanilla comes through quite clean and clear, but it’s gone in a matter of seconds.

One of the most notable ways in which this formula stands out from the others is the proportion of nonfat dry milk powder, which is higher than all the others. The milk powder helps the relatively low amount of fat in the ice cream base hold onto more air because of the addition of whey proteins, which act as an emulsifier, and the added protein also helps to cut down on iciness. 

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Soft Serve Ice Cream

[link https://www.chefsteps.com/activities/soft-serve-ice-cream Soft Serve (ChefSteps)]

Commercial soft serve machines basically operate just like ice cream machines in that they freeze ice cream base in a container while churning it, with the dasher scraping ice crystals off the walls of the container as they form.

The main difference is that the machines are designed to dispense soft serve on demand. That could mean dispensing a series of cones back to back or dispensing soft serve sporadically; either way, the soft serve has to be ready to go.

The other difference has to do with the fact that soft serve has a significant amount of air churned into it (soft serve overrun lies between 30–60%). As a result, soft serve machines have features designed to inject air into mix while it churns.

How Commercial Soft Serve Machines Work

Classification: Light

Sweetness:🍦🍦

Flavor: Like a cold glass of lightly sweetened milk.

Texture/richness: Lean, slightly dense.

Recommended churning method: <a href="https://www.chefsteps.com/activities/liquid-nitrogen-churned-ice-cream">Liquid nitrogen</a> or <a href="https://www.chefsteps.com/activities/making-ice-cream-with-dry-ice">dry ice</a>.

Ideal serve temp: [f 18] to [f 20]

This ice cream tastes like a tall glass of cold, refreshing milk with a sweet and savory finish.

Even though it has a lot less sugar than the previous two examples, it isn’t hard or icy, thanks to the kinds of sugar it contains. While there’s sucrose (granulated sugar) in there, there’s also lactose (from the milk and nonfat dry milk powder) and liquid glucose, and these latter two sugars make ice cream softer because they lower the freezing temperature of the ice cream base. (See the section above on “Sugars in Ice Cream.”) It also has the most salt of any of the ice creams in the parametric; we originally developed this recipe for a <a href="https://www.chefsteps.com/activities/course-4-farm-and-garden-savory-ice-cream-salad">salad</a> course of a <a href="https://www.chefsteps.com/activities/tasting-menu-spring">tasting menu</a>.

With a little more fat than the two previous examples, it’s not as lean, but it still scans as refreshing and light. 

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Course 4: Farm and Garden (Savory Ice Cream Salad)

Jersey Milk Ice Cream

[link https://www.chefsteps.com/activities/jersey-milk-ice-cream Jersey Milk Ice Cream (ChefSteps)]

Dairy is an important part of ice cream; like ice (see tip above), it’s right there in the name! It contributes water, fat, sugar (lactose), and proteins (casein and whey) to the ice cream base, and each of these elements is what helps produce ice cream’s flavor and unique texture.

There are three dairy products that are commonly used to make ice cream: milk, cream, and nonfat dry milk powder. And they provide different quantities of each of these core elements. These products are used in combination to dial in the base ratios for each element in the ice cream base.

Milk: Milk makes up the largest part of an ice cream base. Milk is about 87% water, and the remaining 13% consists of solids. Milk solids are divided into fat and “solids-not-fat”; whole milk must have at least 3.25% milk fat.

Cream: Cream is added to ice cream base to boost its fat content. Cream contains a varying amount of fat, depending on its classification. Heavy cream, the most commonly used type of cream in ice cream because it’s the richest, must have at least 36% milk fat.

Nonfat dry milk powder: Nonfat milk powder is added to ice cream base to boost its milk solids, which reduce iciness by binding excess water; to depress the freezing point of the base by contributing lactose; and to act as an emulsifier, boosting the amount of air that can be trapped during churning.

The quality of dairy products affects the flavor of ice cream, particularly if the ice cream is “milk-flavored” like fior di latte gelato and our <a href="https://www.chefsteps.com/activities/jersey-milk-ice-cream">Jersey milk ice cream</a>.

High-quality milk and cream tend to contain more fat than commodity milk and cream, and this can affect the texture and flavor of ice cream, not necessarily for the better, as many ice cream recipes are designed to be made with dairy products that contain less fat.

Dairy

Classification: Gelato

Sweetness:🍦🍦🍦 

Flavor: Buttery and milky.

Texture/richness: Rich, creamy, and soft.

Recommended churning method: Pacojet or CREAMi.

Ideal serve temp: [f 10] to [f 22]

When tasting this “flower of milk” gelato, our team noted its “buttery sweetness” in addition to its clean, milk-forward profile. That’s due to the fact that in addition to milk, it includes a fair amount of cream, which bumps up the butterfat proportion significantly when compared with the other milk-flavored ice creams in this analysis—and it’s definitely the richest-tasting ice cream of all the variations that don’t contain eggs.

We selected fior di latte for this parametric analysis because it is one of the two classic “plain” flavors in the Italian ice cream world—the other being crema, which is essentially a plain egg custard. While vanilla is the most popular and common flavor in the United States, it is not a standard flavor that you will find in every gelateria in Italy, although it has come more into fashion in recent years.

This fior di latte from master gelatiere Paolo Brunelli is quite sweet, but not as sweet as it could be, thanks to the fact that it has both granulated sugar (sucrose) and dextrose, which is about 75% as sweet as sucrose. Dextrose, however, lowers the freezing point of the base more than sucrose, giving this ice cream a softer texture.

Gelato is also frozen to and served at a higher temperature than hard scoop ice cream, so it’s even softer as a result. Another defining characteristic of gelato is its dense and creamy texture, which is achieved by limiting overrun during churning. Commercial machines are specially designed for this (see the tip below), but at home, the best way to re-create this texture is by using a CREAMi or Pacojet.

Fior di Latte Gelato (Paolo Brunelli, Avanguardia Gelato)

Gelato machines are very similar to ice cream machines, since they perform essentially the same function: “dynamically freezing” a base by chilling and churning it at the same time.

But since gelato is chilled to a higher temperature than ice cream, and because it’s characterized by having less air incorporated into the base during churning (overrun), there are some key differences.

Limiting overrun is the main difference. Gelato is churned in airtight containers, which limits the amount of available air that can be incorporated into the freezing base. Gelato dashers also mix at a slower rate, which also limits overrun.

How Commercial Gelato Machines Work

In Italy, gelato is ice cream. Outside of Italy, gelato is considered a style of ice cream.

In the United States, there are stricter rules for what can be classified and sold as gelato, ice cream, or frozen custard (or French ice cream), and they’re instructive. Gelato typically is made with greater proportion of milk than American hard scoop ice cream, which means it tends to have less fat, and gelato formulas tend to have less sugar. Gelato machines (see above) churn more slowly than American ice cream machines, incorporating less air, which produces a denser product.

For all these reasons, gelato is also best served at a higher temperature ([f 10] to [f 22]) than hard scoop ice cream ([f 6] to [f 10]), and it won’t survive in a cold freezer for very long without becoming icy (see the tip about ice and recrystallization at the top of the page).

Gelato vs. Ice Cream: What’s the Difference?

Classification: Standard

Sweetness:🍦🍦🍦 

Flavor: Eggy, with strong vanilla notes.

Texture/richness: Buttery and rich with a pleasing density.

Recommended churning method: <a href="https://www.chefsteps.com/activities/liquid-nitrogen-churned-ice-cream">Liquid nitrogen</a> or <a href="https://www.chefsteps.com/activities/making-ice-cream-with-dry-ice">dry ice</a>.

Ideal serve temp: [f 6] to [f 10]

Frozen custard is essentially frozen <a href="https://www.chefsteps.com/activities/creme-anglaise">crème anglaise</a>, and like any <a href="https://www.chefsteps.com/activities/custard-parametric-analysis">custard</a>, it’s got a fair amount of eggs in the base.

This ice cream is a lot like a pint of Häagen-Dazs vanilla: eggy, but not in your face, with a vanilla-forward flavor profile, and a tempered sweetness (thanks to the fact that it uses less sugar than the examples above and has a much higher proportion of fat).

And that fat doesn’t just mute the sweetness: The vanilla dissipates fairly quickly, and you get a little savoriness, followed by rich butteriness as the fat melts and coats your tongue. 

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Frozen Custard

[link https://www.chefsteps.com/activities/this-frozen-custard-is-one-smooth-sonuvagun Frozen Custard (ChefSteps)]

Classification: Super Premium

Sweetness:🍦🍦🍦 

Flavor: Key lime pie-ish.

Texture/richness: Very soft, dense.

Recommended churning method: Pacojet or CREAMi.

Ideal serve temp: [f 6] to [f 10]

The oddest ice cream in the lineup, simply because it calls for lime zest, which gives it a Key lime pie kind of vibe. (While two kinds of vanilla are used in the base, the lime sort of takes over.) The consensus from our tasting was that the flavors are a little busy—there’s a lot going on.

This is one of the softest ice creams of the bunch, thanks to both the relatively high proportion of sugar and the types of sugar used; in addition to granulated sugar (sucrose), the base contains dextrose (which is less sweet than sucrose, but lowers the freezing point more) and Trimoline, an invert sugar syrup that, while sweeter than dextrose, also lowers the freezing point more than sucrose.

All that sugar doesn’t quite translate to perceived sweetness, however, thanks to the egg yolks in the custard base.

[link https://www.amazon.com/French-Laundry-Se-Thomas-Keller/dp/1579658490/ Vanilla Ice Cream (Thomas Keller, The French Laundry, Per Se)]

A lot of ice cream science is focused on the way ice cream has been traditionally made: churning. The “dynamic freezing” process that creates ice cream requires that a liquid ice cream base be frozen while it’s continuously agitated by a dasher, which is also scraping ice crystals that form on the super-cold sides of the ice cream base container.

But 30 years ago, a new tool emerged for making ice cream that doesn’t use dynamic freezing at all: the Pacojet. More recently, Ninja began producing a similar machine, called the CREAMi, and both machines operate on the same principles, although they have some key differences.

With these machines, instead of churning liquid base into a frozen treat, the base is transferred to beakers specifically designed to fit in these machines and frozen solid. Once frozen solid, the beakers are loaded into the machines, and a rotating blade that spins at up to 2,000 rpm is steadily forced through the frozen base, shaving it and bludgeoning it into super-fine particles.

There are three main ways in which this process differs from traditional ice cream churning. Whereas in traditional ice cream churning, the goal is to limit the size of ice crystal formation, with the Pacojet and CREAMi, large ice crystals are allowed to form, because they’re subsequently pulverized into tiny crystals. In traditional ice cream machines, the ice cream base is chilled as it churns; spinning frozen ice cream base in a Pacojet or CREAMi actually warms up the base because of the friction created by the blades. And, finally, the spinning blades don’t incorporate as much air as a dasher, so the resulting ice cream is more dense.

The result of this process—commonly referred to as “spinning” or “Pacotizing”—is ultra-smooth and creamy ice creams.

In our experience, these machines perform best for ice cream styles that have limited overrun, as well as ice cream bases that contain stabilizers and have between 6% and 15% total fat.

How the Pacojet and CREAMi Work

While the two machines are very similar, the Pacojet is designed for and marketed to professionals, so there are some key differences.

The benefits of a Pacojet:
 
Its blade spins at 2,000 rpm, whereas the CREAMi tops out at about 1,800 rpm. 

It uses blasts of pressurized air while the blade is spinning, which creates a shattering effect, pulverizing the ice more efficiently. 

Because of that functionality, the Pacojet allows you to both increase and decrease the amount of air in the ice cream (overrun).

It has a larger beaker capacity (1 liter) than the standard CREAMi beaker, and the beakers are made of durable stainless steel instead of plastic.

Pacojet beaker lids are designed in a way that removes air from the canister, giving you more control over overrun.

The benefits of a <a href="https://www.amazon.com/Ninja-NC301-placeholder-Cream-Maker/dp/B08QXB9BH5?tag=chefsteps02-20&th=1">Ninja CREAMi</a>:

It has a much lower price point. The entry-level CREAMi costs under $250, while the newest model Pacojet costs over $7,000.

It has variable blade rotation speeds and programs that are designed for different kinds of ice cream.

It makes ice cream that’s nearly as good as a Pacojet.

Ninja releases new models frequently.

(For a great overview of how these machines work and how they differ from one another, check out our co-founder and old friend <a href="https://www.youtube.com/watch?v=HCJsaPefl1c">Chris Young’s comparative video review of the two machines</a>!)

Pacojet vs. CREAMi: What’s the Difference?

Classification: Premium

Sweetness:🍦🍦🍦🍦 

Flavor: Robust vanilla. 

Texture/richness: Light and lean.

Recommended churning method: <a href="https://www.chefsteps.com/activities/liquid-nitrogen-churned-ice-cream">Liquid nitrogen</a> or <a href="https://www.chefsteps.com/activities/making-ice-cream-with-dry-ice">dry ice</a>.

Ideal serve temp: [f 6] to [f 10]

And we’re back to skipping eggs! The lack of eggs in the base means this ice cream scans as both quite sweet and very vanilla-y. In fact, it’s the most vanilla-forward flavor profile of them all, because we use both vanilla extract and vanilla bean to provide a rounded, complex vanilla flavor that builds and builds.

Despite being high in fat, this ice cream eats quite light, because the nonfat milk powder in the base allows for a lot of air to be trapped during churning. It has the third highest overrun out of the ice creams—Jersey milk ice cream and ice milk have just a little more air.

And while it’s quite sweet, the perceived sweetness isn’t coming from a higher proportion of sugar compared with the other ice creams in this analysis; in fact, its sugar quantity lies on the lower end of the spectrum. It’s just because the base doesn’t contain eggs!

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Egg-Free Vanilla Ice Cream

[link https://www.chefsteps.com/activities/egg-free-vanilla-ice-cream Egg-Free Vanilla Ice Cream (ChefSteps)]

“Overrun” refers to the amount of air that’s incorporated (and trapped) into ice cream as it churns, and it’s primarily determined by the way fat in the ice cream base behaves during freezing and churning. That air is what gives ice cream its fluffy texture, but it also affects how quickly ice cream melts. If an ice cream has only a little overrun, it’ll be denser, but it will melt faster; if it has too much, it will be fluffier, but it will melt more slowly.

Overrun is measured as a percentage increase in volume in the ice cream base. For example, if 1 liter of ice cream base is churned to yield 1.5 liters of ice cream, it has 50% overrun. Here’s the formula for calculating overrun: [(final ice cream volume - ice cream base volume)/ice cream base volume] x 100.

Overrun is often used as a metric for quality, since regulatory standards for ice cream use density as a criteria (“<a href="https://www.ams.usda.gov/grades-standards/ice-cream">Ice cream shall ... weigh not less than 4.5 pounds to the gallon ...</a>”).

Consequently, ice creams with more overrun (generally 100% or above) are considered inferior, as they are the least dense. (“Super premium” ice cream, for example, has the lowest amount of overrun, whereas “economy” ice cream can push the limit, so long as the churned ice cream satisfies the minimum density regulation.)

Improving the ability of an ice cream base to trap gas during churning is an important part of making ice cream. It’s the reason why emulsifiers are added to ice cream base and the base is blended (“homogenized”), and it’s the reason why the ice cream base is chilled and thoroughly “aged” before churning. These processes help fat globules crystallize, which in turn makes them more likely to stick together (“partial coalescence”) and trap air.

Overrun, Explained

Frozen custard and ice creams that are labeled as “French-style” contain lots of egg yolks—it is, as the name suggests, basically a frozen crème anglaise.

Frozen custards are rich, thanks to the fat that egg yolks bring to the formula, and taste, well, eggy, which can mask other subtle flavors like vanilla, and mute the sweetness of the ice cream base formula. You can control the egginess of the ice cream by cooking the base to a lower temperature before chilling and churning it into ice cream.

As egg proteins denature, a sulfur compound breaks in half to become what our brains associate with the flavor of eggs, meaning the hotter you cook the custard, the eggier it will taste. If you cook the custard at a lower temperature, more proteins stay intact, so the finished product tastes less like those sulfur compounds and therefore less eggy.

For more about non-frozen custards, check out <a href="https://www.chefsteps.com/activities/custard-parametric-analysis">our parametric analysis of custards!</a> 

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Eggsamining Custards: A Parametric Analysis

Eggs, Ice Cream, and Frozen Custard

Emulsifiers and stabilizers often get a bad rap, but the truth is, there’s nothing scary about them; they’re just ingredients that help improve the texture and shelf life of ice creams in different ways.

Emulsifiers 
 
Common emulsifiers: Egg yolk (lecithin), nonfat dry milk powder (whey).

Emulsifiers are primarily added to ice cream to improve its ability to trap air (overrun) during churning. Counterintuitively, emulsifiers are added to ice cream base to weaken the dairy emulsion. And it has to do with crystals—not ice crystals, but fat crystals, since frozen fat is responsible for trapping the air in ice cream.

Dairy, a fat-in-water emulsion, naturally contains emulsifiers—casein and whey proteins. Casein is a strong emulsifier, and it will form groupings (called micelles) around fat globules, preventing them from combining (coalescing)—that’s why the fat and water in cream and milk, particularly when homogenized (i.e., the fat is broken up into tiny globules), don’t separate; the casein helps maintain stable emulsions.

The problem with casein is it’s too strong, and it prevents fat globules from forming crystals when it freezes.

When other emulsifiers, such as lecithin in egg yolks, whey, monoglycerides, diglycerides, and polysorbate 80, are added to ice cream, they replace some of the casein in the micelles surrounding the fat globules, which allows the fat globules to crystallize when frozen. Crystallized fat globules will stick to one another (this is called “partial coalescence”), forming networks that can trap air more efficiently, which in turn produces the frozen foam we all love.

Getting fat globules to partially coalesce is a huge part of good ice cream making, and it is the reason why all ice cream bases are blended, even if they seem completely homogenous. Blending homogenizes the mix, shearing the fat into tiny globules, and encourages emulsifiers to replace casein proteins that attach to the outsides of those globules.

Stabilizers

Common stabilizers: Locust bean gum, guar gum, carrageenan (iota, kappa, and lambda), xanthan gum.

Stabilizers are primarily added to ice cream to improve its freezer shelf life, but they also play a role in improving texture and the resilience of the ice cream to temperature fluctuations. The mechanism is fairly simple, as the beneficial effects of stabilizers are directly related to how they bind water and increase the viscosity of the ice cream base.

<a href="https://www.chefsteps.com/activities/unlock-your-hydrocolloid-starter-pack">Hydrocolloids</a> are commonly used as ice cream stabilizers, and technically, eggs act as a stabilizer, too. As the ice cream base’s viscosity increases, it will seem to be creamier, it will melt more slowly, and ice crystals won’t grow as rapidly during storage.

The stabilizers listed above are commonly used together in ice cream formulas, and you can purchase stabilizer blends or buy each ingredient individually. Here is what some of those ingredients do.

Locust bean gum (LBG): Derived from the carob tree pods, locust bean gum suppresses iciness and adds body to ice cream. If used on its own and in excess, it can create an unpleasant, mucus-like texture. LBG can also cause wheying off, which is when whey separates from the ice cream base as it melts. To prevent this, LBG is often used in conjunction with other stabilizers like carrageenan.

How much to use: 0.05% to 0.1% of ice cream base by weight.

Guar gum: Guar gum is derived from guar beans and adds a lot of viscosity to ice cream base, and it works synergistically with LBG, with each boosting the effects of the other. As result, they’re often used in combination. Used in higher proportions, guar gum can impart chewiness to ice cream.

How much to use: When used with LBG, 0.05% to 0.1% of ice cream base by weight.

Carrageenan: Derived from seaweed, carrageenan improves the mouthfeel and texture of ice cream. There are three kinds of carrageenan: lambda, iota, and kappa. Kappa carrageenan forms firm gels, iota carrageenan forms elastic gels, and lambda carrageenan is a thickener. Iota and kappa work synergistically, and they are more beneficial for custards and set desserts (like our <a href="https://www.chefsteps.com/activities/flourless-carrot-cake">Flourless Carrot Cake</a>) than ice cream. Lambda carrageenan thickens dairy without gelling, and, like the other forms of carrageenan, prevents wheying off when used in conjunction with LBG.

How much to use: 0.02% to .06% of ice cream base by weight.

Emulsifiers and Stabilizers

Classification: Super Premium

Sweetness:🍦🍦🍦 

Flavor: Complex and long-lasting vanilla.

Texture/richness: Custardy and thick.
 
Recommended churning method: <a href="https://www.chefsteps.com/activities/liquid-nitrogen-churned-ice-cream">Liquid nitrogen</a> or <a href="https://www.chefsteps.com/activities/making-ice-cream-with-dry-ice">dry ice</a>.
 
Ideal serve temp: [f 6] to [f 10]

This is our “vanilla is amazing” ice cream: It’s got deep, complex vanilla flavor that lasts and lasts, thanks to both vanilla extract and vanilla bean in its custardy base, which lets the vanilla linger a little longer on your palate.
 
In many ways, this is our ideal vanilla ice cream (sure, we created it, but still!). It’s sweet, but not too sweet; it’s rich, but not as rich as the French Laundry’s; it’s custardy, but not too eggy; and it’s got a pleasingly thick texture that walks right up to the line of being chewy, sort of reminiscent of the texture of butter on toast that hasn’t been properly tempered.
 
In a word, it’s balanced: the Goldilocks vanilla.
 

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Vanilla Bean Ice Cream

[link https://www.chefsteps.com/activities/vanilla-bean-ice-cream Vanilla Bean Ice Cream (ChefSteps)]

This is one of the OG ChefSteps hacks for making amazing ice cream at home. It uses a piece of equipment that you may already have (a stand mixer) and a widely available special ingredient (dry ice) to make ice cream that’s better than any countertop ice cream churner!

The reason it’s so effective is because it addresses the greatest challenge of making ice cream head-on: freezing the base fast to form the smallest ice crystals possible.

All you need to do is add your base to the bowl of a stand mixer fitted with the paddle attachment, and then start the mixer. As the paddle churns the base, you gradually add crushed dry ice or liquid nitrogen to the bowl, which rapidly freezes the base. The churning process takes minutes and produces some of the smoothest and creamiest ice cream you’ll ever make at home.


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Churning Ice Cream With Dry Ice or Liquid Nitrogen

Vanilla is, in fact, not very “vanilla,” if you know what we mean. While its name is often used pejoratively to denote the humdrum and run-of-the-mill, it is one of the most complex spices in the world.

For the best vanilla-flavored ice cream, you have to use good quality vanilla products. Here are our recommendations:

Vanilla extract: Pure vanilla extract is a vanilla bean–infused solution of alcohol and water. It captures the volatile alcohol- and water-soluble aroma and flavor compounds contained in vanilla beans. Imitation vanilla often falls far short of the pure stuff as it’s one-note.

Recommendations: Look for “pure” or “single fold,” like <a href="https://www.amazon.com/Nielsen-Massey-Vanillas-Tahitian-Vanilla-Extract/dp/B000E7F5SQ?tag=chefsteps02-20">Nielsen-Massey Tahitian Pure Vanilla Extract</a> and <a href="https://www.amazon.com/Pure-Vanilla-Extract-Hand-Selected-Polynesia/dp/B01KMVK6T6?tag=chefsteps02-20">Heilala</a>—the ingredient list should have just vanilla bean, alcohol, and water.

How to use vanilla extract: Add extract to ice cream base at or below [f 140] to preserve the volatile flavor and aroma compounds.

Vanilla bean paste: Vanilla bean paste is a paste made from vanilla seeds, vanilla extract, and some kind of binder. It has a more complex flavor than vanilla extract, thanks to the seeds. The seeds add a pleasing visual element—tiny black speckles—to whatever the paste is added to. While not as flavorful as using vanilla beans, vanilla bean paste is less expensive.

Recommendations: We like the vanilla bean paste from <a href="https://www.amazon.com/Vanilla-Bean-Paste-Baking-Sustainably/dp/B0CB78BQGC?tag=chefsteps02-20">Heilala</a>, which has great flavor. An added bonus is Heilala includes the percentages of ingredients on its label, which is useful for dialing in and adjusting ice cream formulas, if needed.

How to use vanilla bean paste: Just like with the extract, add vanilla bean paste to ice cream base at or below [f 140] to preserve the volatile flavor and aroma compounds.

Vanilla beans: The real McCoy, vanilla beans are the seed pod of the vanilla orchid, a notoriously temperamental plant that is difficult to cultivate. To produce seed pods, the orchids must be hand-pollinated, and once the seed pods are harvested, they go through a lengthy drying and curing process, during which its many aromas and flavors are developed. Both the pod itself and the seeds it contains can be used to add flavors and aromas to food.

Recommendations: When buying vanilla beans, the most important thing is that they should be plump and moist, not shriveled and dried. We recommend <a href="https://www.amazon.com/Madagascar-Harvest-FITNCLEAN-VANILLA-Vanilla/dp/B09SNVYF9X?tag=chefsteps02-20">buying vanilla beans in larger quantities</a>, as the price per bean drops significantly. Vanilla beans can be vacuum-sealed and frozen for months with no loss in quality.

How to use vanilla beans: Using a sharp knife, split the vanilla bean(s) lengthwise and scrape out the seeds. Add the vanilla seeds to the base before heating; add the pod to the base after the base has been strained to let it steep for the duration of the aging process. Remove the pods before churning.

Putting the Vanilla in Ice Cream

Ice cream is so commonplace that it’s easy to forget how incredible it is. It isn’t just that it’s one of the most delicious creations humans have ever devised—creamy, sweet, and cold—for summer eating. It’s that it’s a technological marvel, a substance that is liquid, solid, and gas at the same time. Add in the fact that the word “ice cream” refers to a range of preparations, all frozen and creamy and delicious, but with significant differences in formulas, churning methods, and ingredients, and what does that mean? It means it’s a perfect preparation for parametric analysis! As with our previous parametric analyses, like the ones for <a href="https://www.chefsteps.com/activities/cheesecake-parametric">cheesecakes</a>, <a href="https://www.chefsteps.com/activities/custard-parametric-analysis">custards</a>, <a href="https://www.chefsteps.com/activities/parametric-pie-dough">pie crusts</a>, <a href="https://www.chefsteps.com/activities/the-ultimate-guide-to-chocolate-chip-cookies-when-average-equals-amazing">chocolate chip cookies</a>, <a href="https://www.chefsteps.com/activities/the-best-brownies-parametric-recipe">brownies</a>, and <a href="https://www.chefsteps.com/activities/ground-meat-skewers-parametric-analysis">kebabs</a>, we chose a few recipes from reputable sources and made (and updated!) some of our own to showcase a representative sample of ice cream variations. We then created a chart that lines them up from lean to super-rich and breaks them down by the numbers.The world of frozen treats is so expansive that we limited our selections to just ice cream—no <a href="https://www.chefsteps.com/activities/fromage-blanc-sorbet">sorbets</a>, <a href="https://www.chefsteps.com/activities/tips-tricks-homemade-granita">granitas</a>, or <a href="https://www.chefsteps.com/activities/popsicle-geekery">popsicles</a> here. We also stuck to vanilla- and milk-flavored ice creams—no chocolate, strawberry, pistachio, or what have you—to keep the formulas consistent and make them easier to compare with one another. If you want to learn more about making ice cream, check out our <a href="https://www.chefsteps.com/classes/ice-cream">Ice Cream Class</a>!