Why is my ice cream icy?
Ice cream feels smooth when its ice crystals are too small for your tongue to notice. When it tastes icy, the crystals have grown big enough to feel. Almost every time, the cause is water: too much of it is free to freeze, or the ice had time to grow into large crystals.
Where does the iciness come from?
Ice cream is mostly water. As it freezes, part of the water turns to ice and the rest stays liquid, a thick syrup of sugars and milk solids around the crystals. The more free water, the more ice, and the more room the crystals have to grow.
What keeps the crystals small?
- Sugars. Dissolved sugars lower the freezing point, so less of the water turns to ice. Too little sugar, and more water freezes.
- Solids. Milk solids, fruit fiber, cocoa and nut pastes take the place of water and thicken the syrup between the crystals.
- Fat. Fat from cream, egg yolks or nuts doesn't turn into ice, and it makes the texture feel creamier. Low-fat bases tend to taste icier.
- Stabilizers. Tiny amounts of gums such as tara, guar or locust bean gum hold on to water and slow crystal growth in storage.
Why does it get icier in the freezer?
Temperature swings. Each time the freezer door opens or the tub sits on the counter, the smallest crystals melt a little. When the cold comes back, that water freezes onto the bigger crystals, so they keep growing. Ice cream that has melted and been refrozen turns icy fast. A tight lid, a spot at the back of the freezer and a piece of parchment pressed onto the surface all help.
Does the machine matter?
Churn machines freeze the mix while stirring it. The faster that happens, the smaller the crystals. That's why a fully frozen bowl (or a pre-cooled machine) and a well-chilled mix make a difference. A Ninja CREAMi works the other way around: you freeze the base solid first, then a blade shaves it into ice cream. A watery base freezes into a block with bigger crystals.
What about sorbets?
Sorbets have no fat or milk solids, so sugars and fruit solids do all the work. A thin juice brings fewer solids than a thick puree, so it freezes icier unless the recipe makes up for it.
How gellatti helps
In gellatti you start from the flavor. Pick it, choose your machine and how much to make, and gellatti's engine works out a balanced recipe to the gram for that machine, with ingredients you can buy locally. Exact grams come with the HOME or PRO plan.
Questions and answers
Why does my homemade ice cream get icy after a few days?
Temperature swings in the freezer let small ice crystals melt and refreeze onto bigger ones. Keep the tub tightly closed at the back of the freezer, and try not to let it soften and refreeze.
Does more sugar make ice cream less icy?
Up to a point, yes. Sugar lowers the freezing point and adds solids, so less water turns to ice. Too much makes ice cream overly sweet and soft, so sugar has to be balanced with fat, solids and the way you serve it.
Why is my Ninja CREAMi ice cream icy?
Usually the base has too much free water: little sugar, fat or solids, or lots of juice or skim milk. A re-spin can smooth it out, but a base with more body freezes into finer crystals from the start.