The Science and Tech Behind Making Ice Cream

The days are getting longer, and the sun has never been stronger—it’s a good thing President Ronald Reagan had the foresight to declare July, one of the hottest months out of the year, National Ice Cream Month. In honor of this great American tradition, we here at BuyDig are going to equip you with the knowledge you need to make the most of this all American pastime.

The Science Behind Ice Cream

We all know what ice cream is—a delicious frozen treat, but do you really know what it’s made of? If you really think about it, this frozen dairy product is a lot more than just sugar and cream; it’s actually a complex, multifaceted emulsion of ice crystals, air, sugar, milk fats, proteins, and other solids. Getting all those different ingredients to form one cohesive emulsion is an amazing quirk of chemistry, but fortunately for the rest of us, you don’t have to understand the laws governing emulsions to make delicious ice cream at home.

How Ice Cream is Made

If you had to worry about building up an ice cream empire like Bryers or Ben and Jerry’s you would definitely want to brush up on your knowledge of emulsifiers, stabilizers, and aeration processes. Fortunately, making ice cream at home is just a matter of mixing the right ingredients together. Here’s a brief overview of the science and tech behind making ice cream to better appreciate this wonderful summertime treat.

Get your Ingredients to Stick Together with Emulsifiers

The ingredients of ice cream quite literally behave like oil and water. The trick to getting them to harmonize into the smooth delicious base you know of as ice cream is to mix in an emulsifier. The industry may have all manner of complex sounding chemicals to fulfill this role, but at home you can put your faith in the incredible edible egg. It’s all natural, and since you don’t have to worry about shelf life, you can take advantage of this incredibly delicious and nutritious ingredient.

Improve the Texture and Feel of your Ice Cream with Stabilizers

It’s the ice crystals within the ice cream that govern the structure, texture and overall mouth-feel of your ice cream. If the ice crystals get too large, your ice cream will feel grainy, and the smaller and more homogenous your ice cream crystals are, the smoother your frozen treat will be. You can use gelatin or starch as a stabilizer to absorb excess water and keep ice crystal growth down. Agar, guar gum, and xanthan gum work great too—experiment and see if you can get the texture you desire.

Prepare the Liquid Ice Cream Base

Take the appropriate proportion of milk,  sugar, and water and mix it with the emulsifier and stabilizer combination of choice. Typically this liquid base will be 60% water (water content of milk included), 15% sugar, and 25% milk fat, but the the emulsion varies with the recipe.

Pasteurization

Unless you’re the type of person who can down raw eggs, most people stand to benefit from pasteurizing the ice cream base by stirring at 185 °F for at least 30 minutes to kill bacteria in the mixture, depending on the size of the batch. Upon completion, chill the base immediately to prevent bacteria growth from coming back.

Homogenization

Homogenization is just a fancy word for thoroughly mixing your ingredients together. Churning the ice cream base at high temperatures can readily free up the fat molecules and reduce their size into tiny droplets, but heat isn’t required. The more evenly distributed your mixture, the better your base will be at absorbing air later in the ice cream making process. Depending on the recipe, you could choose to knead a ziploc bag filled with the ice cream ingredients, whisk them in a bowl with an egg beater, or rely on a mixer like the Cuisinart 5 Speed Stand Mixer pictured above.

Freezing and Aeration

Here’s where you’ll need an ice cream maker, like the Cusinart ICE-30BC or the Cusinart ICE-21R. This specialized machine will whip air into your ice cream base as it slowly freezes. The base is poured into a chamber surrounded by a refrigerant. A steady stream of air is introduced to the barrel as a mixer called a dasher whips the cream. The chilled ice cream that comes out of this step usually isn’t quite ready to eat and may be a little runny. Place it in the freezer for some added stability and you’ll have ice cream ready to go.
National Ice Cream Month is for the entirety of July, so be sure to gear up and be ready to take on the summer heat with some ice cream creations of your own!