The recrystallization of ice cream and sorbet

Why does the texture of your ice cream change during storage?

The quality of ice cream isn’t determined solely by how it comes out of the machine. It’s during storage that the real flaws become apparent: a coarse texture, a gritty mouthfeel, and noticeable crystals when tasted. These issues are often a sign of an imbalance in the ice cream mix’s formulation. Two causes stand out as the most common: water recrystallization and lactose recrystallization.

The recrystallization of water

This is one of the most common problems in ice cream making, yet one of the hardest to anticipate. Freshly churned, ice cream may appear perfectly smooth, but it’s during storage that everything comes into play. When a mix contains too much free water, the ice cream doesn’t crystallize evenly during freezing. It forms large ice crystals, and over time, the smaller ones merge to create larger ones. The result: hard ice cream that’s difficult to scoop, and a texture that gradually loses its smoothness and creaminess.
This phenomenon is generally linked to an imbalance in the mix’s composition: excess water, a lack of small-molecule sugars (glucose syrup, dextrose…), and an insufficient amount of stabilizer are all factors that promote the recrystallization of your ice cream.

How can this be fixed?

The goal is to better control the free water in the mix by adjusting several parameters.
Adding dehydrated glucose or invert sugar helps bind some of this water and limit crystal growth. For richer, drier ice creams (chocolate or dried fruit ice creams in particular), dextrose is a particularly suitable option because it offers even more flexibility than glucose syrup.
Increasing the stabilizer dose in your ice creams is also an effective solution for binding water, refining the texture, and slowing recrystallization during storage.
More generally, it is helpful to check the dry matter content of the recipe using an analytical table to ensure that the recipe does not contain too much water from the outset. To achieve this, using powdered ingredients (glucose, skim milk, etc.) helps limit the amount of water in the recipe.

Lactose recrystallization: the cause of a gritty texture

Although less well known than water recrystallization, lactose recrystallization is just as common in dairy-based ice creams. It results in a gritty texture, with small grains that do not melt on the tongue and significantly impair the taste experience.
The mechanism is as follows: lactose, which is naturally present in milk, cream, and milk powder, must be fully dissolved in the ice cream mix to prevent crystallization during freezing. When the lactose concentration is too high, the water available in the mix is no longer sufficient to dissolve it all. The lactose then gradually recrystallizes during storage.

How can this be fixed?

The solution involves adjusting the MFE (milk fat-free solids). In practice, this means increasing the amount of water in the frozen mix or reducing the quantities of dairy ingredients. Generally speaking, the SML should remain below 11.5%, although this threshold may vary depending on the other ingredients in the recipe and the formulation process. Balancing tables are therefore an indispensable reference tool.

Balance: the key to perfect ice cream

Recrystallization (whether it involves water or lactose) is very often caused by a formulation issue. Mastering the balance of an ice cream mix requires an understanding of the role of each ingredient and the interaction between the various solids, sugars, and stabilizers.

To learn more about these topics, check out all our recipes and technical resources on our website, and sign up for our monthly training sessions to deepen your knowledge of ice cream making.

To learn more about ice balancing, we also recommend the resources from theNational Confederation of French Ice Cream Makers (CNGF), particularly their reference book (CNGF – National Confederation of French Ice Cream Makers) on artisanal ice cream making.