Understanding the role of stabilisers in frozen desserts can provide information that can be easily applied to other foods and beverages.
Stabilizers alter water mobility and thus affect textural properties ( e.g., rheology, appearance uniformity and mouthfeel); physical functionality (e.g. machinability); and/or physical consistency of foods and beverages during production;
Stabilizers prescribe significant quantities of water compared to their own weight. Therefore they are used at ultra-low levels that do not affect the nutritional properties of the food to which they are applied significantly.
Terminology and General Classification
Often known as hydrocolloid gums are stabilisers, since they form colloidal dispersions in water.
Their effects on water mobility arise from a high molecular weight and a complex structure that is strongly branched. Individual molecules or particles of any stabiliser interact with water, and change the water ‘s conduct. Interaction with other components of food also improves the effects of the stabiliser.
Differences in structure between different stabilisers generate a wide variety of properties for water management. The effect in some cases is simply one of increasing the viscosity. Adding more structural complexity can shift water ‘s behaviour from a material that flows naturally and easily to behaviour where flow only occurs with shear application.
At the extreme, gels or gel-like structures are formed which retain shape. This spectrum of rheological effects during processing and/or intake can cause profound behavioural effects.
Secondary factors that further impact the acceptability of any given food or drink involve crystallisation of other food components ( e.g., sugars), release of flavours (good or bad)
In Frozen Desserts Stabilisers
Considering the use of stabilizers in ice cream and related frozen desserts such as sherbets and sorbets, this provides information that can be readily applied to other foods and beverages.
Unlike other foods, ice cream is designed to be manufactured, distributed and consumed in the frozen state. As a result, management of the number and size of ice crystals is a critical element of the perception of both smoothness (a key quality attribute of ice cream) and the coldness that is part of its refreshing appeal. Ice cream’s eating quality also includes the perception of body (bite, chew), in which the organization of ice crystals can play an important role. Besides texture, the amount and structure of ice and the number and size of ice crystals in ice cream also directly influence appearance, aroma
(Chemistry and Aromatic Part Physics Change) and taste (sweet, salty, bitter, sour, umami, etc.). Ultimately all influences the finished food taste.
Functionality of the stabiliser in ice cream is further complicated by the fact that it is a complex food containing fat, proteins and salts whose chemical and physical behaviour is influenced by the volume and physical presence of water
And the control of water and its actions in ice cream takes on an additional dimension. As in other foods, the effect of stabilisers on rheology plays an important role in eating consistency linked to creaminess and wealth perception. Beyond that is preserving smoothness by keeping ice crystal size well below the threshold of perception by reducing water mobility. Owing to the low degree of use of stabilisers, they play only a minor role in influencing the liquid mix properties before freezing. Their primary impact is to add a slight degree of viscosity, with no variation between the effects of the different stabilisers used. However, the effective concentration of the stabiliser increases when water is frozen into ice due to the influence of free This results in the accumulation of the original solutes (sugars, salts, proteins, etc.) and suspended materials (proteins, fat, stabilisers, etc.) in the unfrozen water. At very low storage temperatures, 85 per cent or more of the water is frozen, causing as many as five or more increases in stabiliser concentration in the unfrozen phase water. At such stages, stabilisers are highly evolved This results in the accumulation of the original solutes (sugars, salts, proteins, etc.) and suspended materials (proteins, fat, stabilisers, etc.) in the unfrozen water. At very low storage temperatures, 85 per cent or more of the water is frozen, causing as many as five or more increases in stabiliser concentration in the unfrozen phase water. At such stages, stabilisers are highly evolved
A description of some of the most frequently used frozen dessert stabilizers are as follows.
Guar gum and locust bean gum (a.k.a. carob bean gum) are referred to as galactomannans, in that their molecular configuration involves a central backbone of mannose with branched structures made up of galactose units. Differences in the details of that structure account for differences in their functionality. The cryo-gelling capability of locust bean gum helps make it the most effective of stabilizing gums in controlling ice crystal size.
The cryo-gelling capability of the locust bean gum helps make it the most effective to regulate ice crystal size by stabilising the gums. It also demonstrates useful degrees of compatibility with other stabilisers including carrageenan and xanthan gum. Guar gum is used widely because of its relatively low cost, although it is less effective than locust bean gum. The branches are formed by interacting with reactive elements of the dextrose chain from different organic entities. These materials are assigned names by the identification of the particular structures used for the branching. The addition of carboxymethyl groups thus shapes carboxymethyl cellulose, the most widely used cellulose gum in ice cream, sometimes referred to as “CMC” or known by the normal name. CMC is often preferred because of the desirably chewy body associated with its presence. A broad range of functional CMC properties is possible by controlling the degree of substitution and the length of the cellulose backbone.
Some cellulosic gums have special uses in frozen desserts. For instance, hydroxypropyl methyl cellulose (HPMC) provides water ices and sorbets with whippability and shape retention properties that are useful in producing extruded forms of those products. Hydroxypropyl cellulose (HPC) provides control of whippability and water mobility which promises useful functionality in ice cream
Carrageenans are derived from seaweed and are available in many forms varying in their rheological effects, mainly in terms of the presence or absence of gel-forming capacity. Some carrageenans function in dairy applications through an interaction with the milk protein which produces very high viscosity or gelling at low carrageenan levels. This relationship is also desirable in ice cream
Xanthan gum is a microbial polysaccharide that offers stable rheological properties under a variety of conditions for formulation and processing. It has become a useful stabiliser in a wide variety of food items but is seldom used in ice cream, mostly because more cost-effective alternatives are available.
Alginates are alginic acid salts extracted from kelp which associate variable properties with variable proportions of D-mannuronic and L-guluronic acids. Alginates are used extensively in foods. Their rheological effects include gels forming when calcium is present. Sodium alginate use in US ice cream has declined, but it is still common in other parts of the wood Many fruits and vegetables contain Pectic substances. They differ in the volume and position of polygalacturonic acide methoxy groups. High- and low-methoxyl pectins in the presence of acid, sugar and/or multivalent cations are available which differ in their ability to attract, immobilise and eventually gel. Pectins can usually be found in extremely sugary, low-pH frozen desserts, such as
The Bottom Line
Stabilizers function in ice cream in a variety of ways. These functions translate well to other foods and beverages. Consider the following:
Prevention of liquid/solid separation.
Effects on processing behavior.
Influence on eating quality — mouthfeel and flavor release.
Protection against protein destabilization and subsequent syneresis.
Manage ability to take and hold air.
Secondary involvement in fat agglomeration (destabilization).
Control of ice crystal size.
Control of crystallization of non-aqueous components (lactose, dextrose).
Control melting/thawing behavior (shape retention, syneresis and appearance).
Provide desirable eating qualities in fat-modified and other health-responsive products.
Since the results differ greatly with the quantity, form and composition of stabiliser systems, it is often better to have a particular stabiliser system designed to meet the specific functional needs of any food.