Galacto-Oligosaccharides (GOS)
Soluble galactose-based oligosaccharides for nutrition products and foods where fibre is incorporated into the dissolved carbohydrate phase.
Ingredient overview
GOS is a mixture of short carbohydrates containing galactose units. Commercial production commonly uses enzymes to convert lactose into oligosaccharides with a range of chain lengths and linkages. The resulting preparation may also contain residual lactose, glucose and galactose.
Purification determines the balance between GOS and these accompanying carbohydrates. This distinction is central to the ingredient's composition: a GOS preparation is a carbohydrate mixture rather than a single chemically uniform molecule. Lactose-derived GOS also has a different source identity from plant-derived fructan or dextrin fibres.
Functional characteristics
| Characteristic | Technical profile |
|---|---|
| Water behaviour | Dissolves into the liquid phase rather than forming insoluble particles. |
| Viscosity | Contributes soluble solids with less thickening than long-chain gelling fibres. |
| Carbohydrate profile | Active GOS and residual sugars form separate parts of the composition. |
| Sweetness | Varies with the balance of oligosaccharides and accompanying sugars. |
| Physical form | Powder and syrup formats introduce different quantities of water and dry solids. |
Applications
| Application | Ingredient role | Contribution to the product |
|---|---|---|
| Nutrition powders | Soluble oligosaccharide inclusion | Distribution within a carbohydrate and protein blend. |
| Cultured dairy | Addition to the soluble solids phase | A compatible format for lactose-derived material. |
| Nutrition beverages | Dissolved fibre-containing solids | Limited particulate contribution. |
| Bars and soft foods | Inclusion within binder systems | Changes to solids, sweetness and moisture balance. |
Formulation behaviour
Powdered GOS disperses and dissolves in the water available to the formulation. In dry blends, particle size and moisture uptake affect flow and distribution. Syrup incorporation depends on syrup solids and temperature, both of which influence pumping and mixing.
Residual lactose and reducing sugars participate in the product's broader chemistry. In protein-containing foods, their presence affects browning during heat treatment and storage. Residual lactose also remains a separate compositional feature from the GOS fraction. Lactose-derived GOS retains a milk-derived source identity. The degree of purification determines its residual lactose and protein content.
Material forms
GOS powders and syrups differ in oligosaccharide concentration and residual sugar profile. Enzyme systems also produce different linkage and chain-length distributions. A concentrated powder, a lower-concentration powder and a syrup therefore represent distinct compositions even when they share the GOS name.
Comparison with related ingredients
FOS is fructose-based and commonly originates from sucrose or inulin. XOS is composed of short xylose chains. PHGG is a hydrolysed polysaccharide with a much larger molecular structure than these oligosaccharide families.