Why use an ice cream calculator?

Making ice cream is simple, until it isn't.

When you're starting off, it's easy to follow a proven recipe and make something delicious. But as you start experimenting with new ingredients, flavors, and techniques, you may run into some common issues:

• The ice cream is too hard (or too soft) out of the freezer
• The ice cream is too sweet (or not sweet enough)
• The ice cream is too icy
• The ice cream melts quickly and has a thin texture

In order to solve these problems, ice cream science can help us. As it turns out, there are mathematical relationships between the ingredients you use and the final texture and sweetness of your ice cream.

Most of the time, great ice cream comes down to two main factors: how soft your ice cream is out of the freezer, and how sweet it tastes.

#Predicting ice cream hardness

This is the most critical role of an ice cream calculator. By predicting how hard your ice cream will be out of the freezer, you can ensure that it is perfectly scoopable and will have the correct texture.

The way calculators do this (primarily) is by tracking:

1. Water content
2. Freezing point depression factor (FPDF) of ingredients

The more water you have in your recipe, the more likely it will be to form large ice crystals and become hard. The way to combat this is by adding ingredients which lower the freezing point, such as sugar or alcohol. We quantify this effect as FPDF, which is expressed as a percentage in relation to sucrose. The higher the value, the more powerful the anti-freezing properties.

• Low FPDF: Too little freezing point depression results in more ice formation, leading to a rock-hard texture that is difficult to scoop.
• High FPDF: Excessive depression prevents enough ice from forming, resulting in a soft, “soupy” consistency.

Ingredients often vary in their FPDF. Take, for example, dextrose vs sucrose. Dextrose has 190% the FPDF of sucrose, which is why it is so commonly used in ice cream recipes. By using a calculator, you can easily swap out sugars and other ingredients while maintaining the same FPDF, ensuring that your ice cream remains perfectly scoopable.

#Estimating sweetness

At first glance, sweetness may seem a simple matter of adding sugar to taste. However, as discussed above, sugars are the primary lever for controlling ice cream hardness. This means that you can't adjust sugar on the fly without negatively impacting the texture.

And just like with FPDF, different sweeteners have differing levels of sweetness. This is quantified as Relative Sweetness, which is expressed as a percentage compared to sucrose. Dextrose, for example, is only 70% as sweet as sucrose. This is another reason why it is so commonly used in premium ice cream recipes; it allows for the creation of scoopable ice cream that isn't overly sweet.

By using an ice cream calculator, you can estimate the sweetness ahead of time and prevent last-minute adjustments that could ruin the recipe.

#Other factors

Targeting the correct hardness and sweetness will get you most of the way to a great ice cream, but there are a few other factors as well that a calculator will help you manage:

• Total solids: Too little solids results in a thin, icy texture that melts quickly. Too many solids may lead to a gritty texture.
• Fat content: Targeting a specific fat percentage ensures your ice cream has the perfect balance of creamy mouthfeel and flavor release without becoming unpleasantly greasy.
• Milk solids not fat (MSNF): The primary source of lactose and proteins. MSNF contributes to the body of the ice cream, but too much can lead to a grainy texture.
• Stabilizers: These help maintain the texture and prevent ice crystal formation, but if used in excess will result in a gummy or slimy mouthfeel.
• Emulsifiers: Egg yolks and other emulsifiers improve texture by making it easier to whip air into the ice cream.

#A note of caution: calculators are not gospel

Calculators are useful tools, but they aren't infallible. The chemistry and physics of ice cream have many complex interactions which cannot be perfectly modeled (despite our best efforts!). This means that the numbers you get from a calculator are best used as a starting point, not an exact prediction. Use the numbers to get into the right ballpark, then iterate: taste the base, adjust, churn, and take notes. When the calculator and your taste buds disagree, trust your intuition.

#Summary

For those who like to experiment with different ingredients and want to move beyond basic recipes, understanding how those ingredients interact is essential. And unless you like doing the math by hand, calculators are the best way to apply this knowledge in a practical way.

If you haven't tried using an ice cream calculator before, I highly recommend giving it a shot. Spend less time troubleshooting, and more time enjoying delicious ice cream.