Technical Note #012: Water in Ice Cream - Understanding Its Role in Formulation and Physical Behaviour

Water is one of the main constituents of ice cream. Yet, in formulation, it is often regarded as a simple diluting component, whose effect must be compensated for by sugars, fats and other ingredients.

This approach is incomplete.

Water plays a central role in the structure and physical behaviour of ice cream. Its quantity, as well as the proportion that freezes during cooling, directly influences hardness, texture and the serving conditions of the finished product.

To understand the balance of a formulation, it is therefore not enough to know the total amount of water present in the mix. It is also necessary to understand how this water behaves.

1. Water: Much More Than a Diluting Ingredient

In ice cream, water comes from many sources: water added directly, milk, cream, fruit purées and other ingredients containing moisture.

Its proportion varies considerably depending on the type of product and the formulation used.

However, two recipes containing similar amounts of water do not necessarily produce ice creams with the same texture.

Why?

Because water does not behave independently of the other components of the mix. Dissolved sugars, mineral salts and other constituents influence the conditions under which water freezes. Proteins, fats and stabilisers also contribute, through different mechanisms, to the structure and physical properties of the product.

Water must therefore be considered as part of an overall system in which the components interact to determine the final behaviour of the ice cream.

2. Not All the Water in Ice Cream Freezes

When a mix is cooled below its freezing point, some of its water gradually turns into ice.

However, not all the water freezes at the same temperature.

Sugars and other dissolved substances lower the freezing point of the aqueous phase. As the temperature decreases, an increasing proportion of the water freezes, while another fraction remains unfrozen.

At a given temperature, two fractions can therefore be distinguished:

• Frozen water, which contributes to the formation of the ice phase and strongly influences product hardness.

• Unfrozen water, which remains liquid within the phase concentrated in dissolved substances and contributes to the properties of that phase.

  
  

These two fractions are complementary: together, they represent the total water in the formulation.

Their distribution depends, in particular, on the composition of the mix and the temperature considered.

It is important to understand that unfrozen water does not necessarily indicate excess added water. It is a natural part of the physical system of a properly formulated ice cream.

3. The Critical Role of Sugars

Sugars play an essential role in the behaviour of water during freezing.

By dissolving in the aqueous phase, they lower the freezing point. Their nature and concentration therefore influence the proportion of water that remains unfrozen at a given temperature.

However, not all sugars have the same effect.

At equal mass, different sugars do not necessarily produce the same effect on the freezing point. Their contribution depends, in particular, on their molecular weight and concentration in the aqueous phase.

This is one of the reasons why PAC (freezing point depression power) is a useful formulation indicator, without being a complete description of the physical behaviour of ice cream.

The overall sugar profile, sweetening power and contribution to total solids must be considered as part of a comprehensive approach.

Changing the sugar system can therefore alter the proportion of frozen water at the serving temperature, which in turn affects the hardness and texture of the product.

The water balance depends on the formulation as a whole, not simply on the amount of sugar.

4. Total Solids and the Balance of the Aqueous Phase

Sugars are not the only components involved in the balance of an ice cream mix.

Proteins, minerals, fats, fibres and stabilisers also contribute to the characteristics of the mix, although their mechanisms of action differ.

Total solids quantify the non-water fraction of the formulation. This is an important indicator, but it is not sufficient on its own to predict the behaviour of the product.

Two recipes with the same total solids content can have different physical properties if the nature and proportions of their components are not identical.

A formulation rich in sugars does not necessarily behave like one with the same total solids content but containing more proteins or other ingredients.

It is therefore important to distinguish the total quantity of solids from their nature and their respective effects.

The objective is not simply to maximise total solids, but to develop a formulation that is consistent with the desired texture and intended serving conditions.

5. Why Is Water Content Not Enough to Predict Hardness?

Ice cream hardness depends on several factors, including the proportion of water frozen at the temperature considered.

With comparable compositions and conditions, a higher proportion of frozen water is generally associated with a harder product. However, this relationship alone cannot predict all the mechanical or sensory properties of the product.

Fat structure, the organisation of the ice phase, ice crystal size, air incorporation and the properties of the unfrozen phase also influence texture.

Two simplifications should therefore be avoided:

• assuming that more water necessarily means harder ice cream;

• assuming that PAC alone determines the final texture.

  
  

Professional formulation requires linking the composition of the mix to its physical behaviour while also taking manufacturing and storage conditions into account.

6. Ideal Serving Temperature: A Reference Point for Formulation

The distribution between frozen and unfrozen water depends on temperature. The same formulation therefore exhibits different physical properties depending on whether it is stored at a very low temperature or displayed in a serving cabinet.

As the temperature rises, some of the ice melts. The proportion of frozen water decreases, changing the hardness and texture of the product.

But how can we determine the temperature at which a formulation has a physical state suited to serving?

Gelato Pro Software calculates an ideal serving temperature, determined by default using a reference level of 70% of the total water in the mix frozen.

This percentage can be adjusted by the user, who can select a different value according to their formulation objectives. The software then calculates the temperature corresponding to the selected criterion.

This ideal temperature provides a theoretical reference for assessing the physical behaviour of the recipe. It does not necessarily correspond to the temperature at which the professional actually serves the ice cream.

In practice, the actual serving temperature depends on working conditions. For example, an artisan may serve ice cream from a display cabinet set to −12.5°C. The objective is then to develop a formulation whose calculated ideal serving temperature is as close as possible to this actual temperature, while maintaining suitable hardness for serving.

7. Freezing Curve, Serving Temperature and Hardness: Three Complementary Indicators

To understand the behaviour of ice cream, it is necessary to link the composition of the formulation to its physical properties and the conditions under which it will be served.

Gelato Pro Software provides several complementary tools for this analysis.

The freezing curve

It allows users to visualise how the formulation behaves as temperature changes. It helps them understand how the proportion of frozen water evolves and compare the calculated characteristics of different recipes.

The ideal serving temperature

The software calculates this temperature based on the frozen-water percentage selected by the user: 70% by default, although this value can be changed.

It provides a theoretical reference for developing a formulation suited to the intended serving conditions.

Actual serving temperature and calculated hardness

The actual serving temperature is defined by the user according to their working conditions. For example, it may correspond to the temperature of a display cabinet set to −12.5°C.

In the “Hardness” tab, the user enters this actual serving temperature. It is also important to update the production parameters, particularly the overrun, so that the hardness calculation takes the characteristics of the manufactured product into account.

The software then calculates the hardness corresponding to the selected parameters and shows how it compares with the range considered ideal.

The analysis relies on the consistency of three elements:

• the ideal serving temperature calculated by the software;

• the actual serving temperature defined by the user;

• the hardness calculated at that actual temperature, taking overrun into account.

  
  

The objective is to bring the calculated ideal serving temperature as close as possible to the actual serving temperature, while achieving a hardness within the ideal range.

When these conditions are met, the formulation has a theoretical balance consistent with the selected criteria. If a discrepancy arises, the professional can examine the recipe composition and adjust certain ingredients to bring the results closer to the intended objectives.

This approach makes it possible to assess the effects of changing sugars, water or other ingredients without relying on a single indicator.

These calculations are formulation tools. The final texture also depends on manufacturing, ice cream structure, storage and actual serving conditions. Practical trials are therefore still necessary to confirm the results.

8. Managing Water Means Managing the Overall Balance

Water cannot be balanced in isolation.

Increasing the amount of water changes the concentration of the other components. Changing the sugars alters freezing conditions. Replacing an ingredient can simultaneously affect water content, total solids and several other formulation parameters.

Every change must therefore be assessed in the context of the entire mix.

The formulation process can be summarised as follows:

Mix composition → distribution of frozen and unfrozen water → physical behaviour → texture → serving conditions

This sequence shows why a recipe cannot be assessed solely on the basis of its ingredient percentages or a single indicator.

The result depends on the interactions between the components and the temperature at which the product is intended to be consumed.

Conclusion

Water is much more than a diluting ingredient. Its distribution between frozen and unfrozen water plays an essential role in the physical behaviour of ice cream, particularly its hardness and texture at serving temperature.

Understanding these phenomena requires considering the formulation as a whole: sugars, total solids, proteins, fats and other components interact to determine the properties of the finished product.

With Gelato Pro Software, professionals can simulate the physical behaviour of their formulations, calculate an ideal serving temperature based on the selected frozen-water percentage, and analyse hardness at the actual serving temperature they have defined.

This approach makes it possible to anticipate the effects of formulation changes and work towards a balance suited to the intended serving conditions before moving on to production.