I never thought of making a sous-vide ice cream base until recently, when I happened upon a mention of it in an article. It was a huge ah-ha moment. I mean, I’ve used sous-vide for years and never once thought of this application. The controlled environment of a water bath would ensure that the custard base cooked to the perfect temperature without curdling. I could mix it and walk away while my Anova sous-vide circulator did its thing. Perfect! But I didn’t want to use just any recipe. I’ve sampled excellent ice cream all over the world, and I wanted my homemade version to taste just as good.
First, some history: a few years ago I delved into the science of making ice cream because I wasn’t satisfied with my results at home. I learned tons about stabilizers, custards, milk-to-cream ratios, sugars, and mouth feel. Grudgingly, I accepted that the best homemade ice cream used an egg custard. (For a non-egg version, I now use a variation on the famous Jeni’s ice cream recipe, also good but not as rich.) Still, I hated making the custard on the stove. I wanted rich ice cream without the effort.
The Lazy Person’s Ice Cream Custard
To avoid the stove, I began experimenting with my friction blender to create an ice cream base that worked well. Friction blenders such as the Oster Versa, Vitamix, and Blendtec generate their own heat because of the speed of their blades.
For this sous-vide ice cream base, I started with the recipe I devised for my Oster Versa blender.
The adaptation from blender to sous-vide recipe concerned more about how and when to combine the ingredients than about the device itself. As it turns out, the method ended up being less intuitive for sous-vide but close to how it works in the blender. Instead of refrigerating the cooked custard in its bag, it works best if you remove the custard from the bag to a separate bowl. You can then add flavors to the bowl before chilling, just as you would any base. This minimizes the mess of pouring from the bag into the ice cream maker, and it allows you to adjust flavors to taste. There are exceptions, of course. If you are making peanut butter or chocolate sous-vide ice cream base, those ingredients may be best added to the bag. (I have not included those variations because I haven’t yet tested them.)
Due to my ice cream deep dive, I learned about critical ingredients to make silky ice cream, and I use them here. You need a stabilizer (in this case, tapioca flour), a way to minimize water content (evaporated milk instead of whole milk), and a form of liquid sugar to supplement granulated sugar (corn syrup.)
My research taught me that stabilizers are an essential component to a good ice cream. Here, I chose tapioca flour — also known as tapioca starch — because it thickens at a lower temperature than the more common cornstarch. Certainly, though, you can try cornstarch. In regular recipes, both starches work well to stabilize ice cream and help bind water to inhibit ice crystals.
Other options include arrowroot, guar gum, and xanthan gum, all natural-based. Because I haven’t yet used any of those, I don’t know the measurements. My guess is that arrowroot would be about the same as tapioca flour, and the others, about 1 tsp. or so. Only a guess, though.
Don’t skip the corn syrup. The kind in the store is not the high fructose kind that you’ve been warned about. A thick syrup as part of the sugar is critical to prevent iciness.
Instead of corn syrup, you can use honey, invert sugar, or glucose syrup. I know that one of my favorite ice cream stores, Owowcow, often uses what they call “simple syrup,” but I suspect it’s really invert sugar syrup. They also use honey.
After all is said and done, however, corn syrup is the easiest liquid sugar to find and use. It also does not add a distinctive flavor the way honey does.
Eggs, Milk, and Cream
Gelato can get away with more milk and less cream because it uses egg yolks to add fat and emulsify the base. Unlike gelato, ice cream can be made with or without eggs. No matter which kind you make, however, your ice cream base will rely on the butterfat from cream. If you want a rich, creamy taste and texture, you’ll gravitate toward a custard-based recipe that contains slightly more cream than milk. Too much cream, and you’ll get a strange coating in your mouth. Too much milk, and you’ll get a non-creamy ice milk.
Icy or grainy ice cream frustrates many a home cook, and it all comes down to water content. Because milk is high in water content, you’ll get better ice cream if you use a method to decrease the water. In other words, you need the lesser fat content of milk to balance the cream, but you don’t want the water that comes with it. Tapioca starch and egg yolks achieve that to some degree by binding water and emulsifying. But I learned I could do even more.
Although some recipes add powdered milk, I’ve found that using evaporated milk works the best since the water content is already reduced. That is really your goal: Keep as much water as you can out of your ice cream.
Tips for a Sous-Vide Ice Cream Base
- Use a FoodSaver or similar bag that can handle heat. I squeeze out as much air as possible before using the seal-only option. If you don’t have a FoodSaver or similar appliance, then you can try it with a heavy-duty freezer Ziploc (or similar) bag. Beware, though: any water that seeps in will ruin the base.
- Empty the custard out of the bag and into a bowl or large measuring cup with a spout before you fully cool it. The first time I refrigerated it in the bag. The solidified custard then became difficult to squeeze directly into the machine.
- Add flavorings to the base after you have emptied it into the bowl. This allows you to taste and adjust them.
- Always refrigerate the base for 8-24 hours before freezing.
- Ice cream freezer. I own two compressor ice cream makers, a Whynter and a Cuisinart. Compressor freezers are expensive, but they are also convenient, especially if you want to make several recipes in one day. If you use a freezer bowl type, make sure the bowl has been in the freezer for at least two days.
- Sous-vide circulator or machine. Because you need to maintain 185 degrees for one hour, it’s difficult to use a work-around. I use an Anova, but there are several circulators out there that sell for less — and for more.
Finally, the Recipe for Sous-Vide Ice Cream Base
The great aspect of cooking an ice cream base sous-vide is that, given a large enough container, you can cook several bags of ice cream base at once. Walk away and forget about them for an hour.
6 egg yolks
1 12-ounce can evaporated milk
2 cups heavy (whipping) cream
1 Tablespoon tapioca flour/starch
1/4 cup corn syrup
3/4 cups sugar
Big pinch of kosher salt
Flavorings, nuts, cookies, sauces as desired.
In a small bowl, mix tapioca flour with 2 T of the evaporated milk until smooth. Set aside.
In a medium-to-large bowl, whisk egg yolks until blended. Add sugar, corn syrup, cream, salt, and the remaining evaporated milk. Whisk until well-incorporated. Add the tapioca flour slurry. Whisk until well-combined.
Pour mixture into a 1-gallon size Foodsaver bag. (I place mine inside a bowl so that it’s supported while I fill it.) Squeeze out air, and seal.
Place the bag in a water bath preheated to 185 degrees F. Make sure the bag is fully submerged. Leave for one hour.
Remove bag from sous-vide bath. When the bag is cool enough to handle, cut a wide, diagonal opening in the top, and pour into a bowl. Add non-solid flavoring, and mix well. Refrigerate for 8-24 hours.
Freeze in your ice cream maker until the consistency of firm soft serve or until the temperature is 18-22 degrees F. Add anything solid about 5 minutes from finish. Working quickly, transfer the ice cream into a container, and freeze.
Ice cream needs to ripen in the freezer for at least 4 hours before serving.
Vanilla: Add 1 Tablespoon high-quality vanilla extract to base before refrigerating.
Cinnamon-Bourbon: Add 2 T. bourbon and 1 T cinnamon to base before refrigerating.
Espresso: Add 1-2 T. espresso powder to the warm base before refrigerating. Make sure the coffee is fully dissolved.
Caramel Cashew: Add 1 T vanilla to base before refrigerating. Mix 3/4 cup refrigerated cashew pieces with 1 1/2 cup caramel sauce, either homemade or purchased. After the freezing, layer the ice cream in its container with the caramel-cashew mix. Save some caramel and cashews to drizzle on top.
Mint Chocolate Chip: Chocolate chips and chopped chocolate bars tend to get gritty and flavorless in ice cream. The best way around that is to break the temper by melting the chocolate.
To the base, add 4-6 drops of peppermint oil or 2-3 teaspoons peppermint extract, to taste. If desired, also add 3 drops green food coloring. Pour 4 ounces of melted chocolate, cooled but still pourable, directly into the base as the machine is running 1-2 minutes before the freezing finishes. You may have to break up the chocolate as you transfer the ice cream to a storage container. If you have a little chocolate left in the bowl, drizzle on top. Don’t cheap out on the chocolate. Instead, use high-quality chocolate for superior taste.
Using sous-vide to cook a perfect custard works extremely well. It requires even less work than using a friction blender, although, of course, you need the equipment. The resulting ice cream is dense, creamy, and, best of all, easy to prepare. Although I listed some variations above, the possibilities are almost endless given a good base. I experiment frequently to come up with different flavors. I’d love to hear your success stories.
Debbie Lee Wesselmann