There may be countless definitions of ice cream, but from a physicochemical perspective, we can describe it as a thermolabile foam, as well as a solution, a dispersion, and an emulsion. It is a foam because it contains air bubbles finely distributed throughout a partially frozen continuous phase.
Ice crystals form a dispersion, fat globules form an emulsion, and sugars and minerals form a solution in the continuous phase, which is partially liquid at serving temperature.
Functions of stabilizers
Stabilizers perform many functions in the mix and in ice cream. Some are technological, while others relate to the final sensory perception of the product. They must generate an appropriate viscosity at each stage of production.
Viscosity must therefore be neither too high, which would hinder the movement of the mix through the equipment or prevent proper air incorporation and distribution during whipping, nor too low, which would cause the bubbles to collapse and prevent foam formation. Viscosity also slows the settling of insoluble particles in the mix (such as cocoa fibers) or the separation of fat globules at the surface.
Another function of stabilizers is to reduce recrystallization in ice cream, which occurs as ice crystals grow due to temperature fluctuations during storage, transportation, and dispensing. Depending on the extent of the fluctuations, some ice crystals melt and tend to increase the size of existing crystals, resulting in a loss of perceived creaminess and an icier mouthfeel when those crystals exceed 50 microns.
The hydrocolloid macromolecules that make up stabilizers are responsible for binding as much water as possible to minimize this migration. This must be achieved by correctly combining their characteristics so that the texture does not become elastic.
Within the ice cream structure, the combination of “gums” selected to stabilize the product must give strength and elasticity to the walls of the air bubbles that form the product’s foam. This prevents shrinkage during storage, when the fill level may drop or, in extreme cases, the product may pull away from the container walls.
If the stabilizer components are not selected correctly, the bubble walls will not have sufficient strength and elasticity, and temperature changes may cause changes in the volume of the air inside the bubble, causing it to collapse, releasing air and changing the total volume of the ice cream.
The strength of the bubble walls also slows the loss of shape during melting. As ice crystals and fat crystals melt, water moves through the ice cream structure as part of the normal melting process, with the strength of the air bubbles playing a fundamental role in delaying the loss of shape.
The dosage and type of stabilizers depend on several factors:
- Mix formulation: The greater the solids content, fat content, and quantity and quality of proteins in the mix, the less free water the formulation will contain and, therefore, the lower the required stabilizer dosage.
- Ingredients used: When analyzing the balance of an ice cream formulation, we should not only look at the most familiar parameters, such as total solids, fat, sugars, or milk solids-not-fat (MSNF), but also examine which ingredients make up the formula and how they modify those parameters.For example, demineralized whey and skim milk powder contribute the same amount of MSNF to the formulation, but milk contains more protein and proteins of a different quality. Therefore, a formula containing a certain proportion of whey will require a higher stabilizer dosage to compensate for this lack of protein functionality, even if, based solely on the parameters, its MSNF content is the same as that of a formula containing only milk.
- Processing temperature: Some hydrocolloids have minimum activation temperatures that must be exceeded for the macromolecule to bind the maximum amount of water.
- Storage time: Ice cream with very high turnover, or ice cream produced and sold at the same location, is generally dispensed before the first signs of recrystallization become noticeable, so high dosages or complex products will not be necessary to prevent it.
The stabilizers used in ice cream are high-molecular-weight macromolecules from different sources:
Countless companies manufacture ice cream stabilizers, since creating a blend of these types of components involves almost no difficulty. The complexity lies in the quality control of each raw material and the potential synergies between them. All these raw materials are natural and generally never have a chemically homogeneous composition or one that remains the same over time, even when they consistently come from the same source and supplier.
For this reason, companies that manufacture stabilizer blends devote most of their resources to quality departments, and ice cream manufacturers should be responsible for requesting the quality documentation for each batch received to ensure consistent quality.
Quality characteristics of different hydrocolloids
The following briefly describes the main difficulties that may arise with the ingredients most commonly used as ice cream stabilizers.
Guar gum is obtained from an annual legume native to the arid regions of Asia called Cyamopsis tetragonoloba. India and Pakistan account for 80% of global production, with pods containing 5 to 12 seeds harvested in December.
Guar gum is obtained by grinding and sieving the endosperm. Chemically, it contains 75 to 85% galactomannans, consisting of a D-mannose backbone with beta-1,4 linkages and alpha-D-galactose side chains in a 1:2 ratio to mannose. Depending on the climatic conditions at harvest, the backbone length of the galactomannan molecule may vary, modifying its final viscosity.
The microbiological characteristics of the flour can also cause viscosity to change within a few hours of dissolution.
Another member of the galactomannan family is locust bean gum, which also comes from the flour of the seeds found in the pods of the carob tree (Ceratonia siliqua). Chemically, it is very similar to guar gum, but the galactose-to-mannose ratio is 1:5. These “smooth,” unbranched regions can vary in length and distribution, modifying the energy required for hydration and, above all, its synergy with other hydrocolloids.
Carboxymethyl cellulose, or CMC, has the chemical structure of cellulose with carboxymethyl substituent groups. However, not all types are the same, and a wide variety exists because the number of substituents within the molecule modifies solubility and acid resistance. In addition, the distribution of substituents changes the thixotropy of aqueous solutions, and the degree of polymerization (chain length) changes their viscosity.
Carrageenans are extracts of red seaweeds harvested mainly in the Philippines and southern Chile. They are linear molecules of D-galactose with sulfate ester groups and 3,6-anhydrogalactose. Depending on the ester and anhydrogalactose content, there are different types of carrabioses: kappa 1, kappa 2, iota, and lambda. These have very different functional characteristics, particularly in the viscosity and gel strength they produce.
Blocks of different types of carrageenan may exist within the same seaweed and the same polymer, and their variation depends on factors such as water salinity and temperature, nutrients, and light conditions that year.
All these variations in the hydrocolloids most commonly used as stabilizers demonstrate that, even when a “formulation” exists, blend manufacturers must make the necessary adjustments. Thus, despite differences arising from the nature of the components, ice cream makers must always receive the same “functionality” so that their ice cream has the desired creaminess and smoothness and maintains them over time.
Commitment and technical support
At Grupo Saporiti, we understand that product development and optimization are dynamic processes that require experience and a collaborative approach. That is why we provide our customers with advice and consulting from our specialists and ice cream technicians, who work together to achieve innovative, efficient formulations.
Our laboratories are also open for experimentation and formula adjustments, providing an equipped workspace for bringing new products to life. This commitment to excellence allows us to offer solutions tailored to each customer’s specific needs, ensuring stability, texture, and quality in every development.
Our team of specialists is ready to help you develop balanced formulas that maximize quality and profitability.
