Water in gelato: the most abundant ingredient, and the trickiest

The most complex and most important ingredient, and the hardest to tame. If you’re learning how to make Italian gelato, there’s one ingredient you need to learn to tame in order to move up to the next level: water. It’s by far the most abundant and, paradoxically, the only one that actually freezes. Managing water is half the work behind a quality gelato.

In this article we’ll see why water has such a big impact on the quality of our gelato, how to manage it, and how to balance a recipe in practice.

Far more water than we add

Water doesn’t come only from milk or from the water added to sorbets: almost every ingredient contains a percentage of water. And, powders aside, water is by percentage the main component.

For example, whole milk is about 88% water, cream around 60%, and fruit between 80% and 90%.

Water is therefore also the main ingredient of our final product, the gelato. The amount of water and its freezing temperature define the creaminess and texture of the gelato.

When we put together a gelato recipe we want to control both the amount and the state of the water.

Water should be between 60% and 75% of the product, varying depending on the recipe and on whether we’re making a custard base (crema) or a sorbet.

Free water and bound water

Here lies the heart of it all. It’s not only the amount of water that defines the state of our gelato, but also its state. The water in the mix comes in two forms. Free water is the water held back by nothing: it starts to freeze at 0 °C and, if there’s too much, it forms large ice crystals that ruin the structure and texture of the gelato.

The bound water (or “captured” water) is the water held by the solids, especially in solution with the sugars: it lowers the freezing temperature, resisting the cold better, and freezes only at much lower temperatures.

Solids bind water in two different ways, depending on their nature:

• in true solution: sugars, fruit juices and liqueurs dissolve naturally in the water and lower its freezing point;
• in emulsion: fats don’t dissolve, but are broken up and «bound» to the water molecules by the emulsifiers; they don’t directly affect the freezing point but have a big impact on the texture and structure of the gelato.

Enemy number one: ice crystals

Whenever free water is left over, the cold turns it into crystals. The difference between a silky gelato and a rough, grainy one lies entirely in the size of these crystals: the smaller and more evenly distributed they are, the creamier the gelato.

Two factors help keep the crystals small:

• the churning speed of the batch freezer;
• the cooling capacity of the machine: the faster the cooling, the tinier the crystals stay.

The role of stabilisers

Stabilisers are the best allies against free water. They are the main ingredients of the neutral blends for gelato and sorbets, and their role is precisely to improve the texture and withstand cooling by binding free water.

Stabilisers hydrate by absorbing water during the ageing (maturation) phase. This process forms a network of hydrogen bonds that reduces the mobility of the water and makes it viscous. More viscous, «trapped» water struggles to form large crystals, even during storage in the freezer, extending the shelf life of the gelato.

Stabilisers also allow sorbets, which have no fats or milk powder, to incorporate air and reach a texture comparable to that of a custard-based gelato.

How much water should stay frozen

The question is: at the same temperature, what’s the difference between a creamy gelato, a melted gelato and a hard block of frozen gelato?

The answer is the percentage of frozen water. At serving temperature, a well-balanced gelato has about 75% of its water frozen. That’s the ideal proportion: scoopable, ready to serve and taste. The remaining ~25% is water still in a liquid state, in a transitional phase, which melts if the cold drops and hardens if it rises, determining the relative hardness.

How do we know at what temperature we have 75% of the water frozen? It depends on the recipe. We’ll see how to calculate it based on the ingredients when we talk about the Anti-Freezing Power (AFP) and the freezing curve.