FOS and Oligofructose
Short-chain fructan fibres with high solubility, mild sweetness and a role in the dissolved-solids phase of foods and beverages.
Ingredient overview
Fructooligosaccharides, or FOS, are short chains built principally from fructose units. Commercial preparations include short-chain FOS produced enzymatically from sucrose and oligofructose obtained by partial hydrolysis of inulin. Their chain distributions and residual carbohydrate profiles differ.
These ingredients contribute soluble fibre and bulk with a sweeter profile than many long-chain fibre preparations. They are useful where dissolved solids are part of the formulation architecture, including dairy products, nutrition powders and binder systems. They do not form the same hydrated particle networks associated with long-chain inulin.
Functional characteristics
| Characteristic | Technical profile |
|---|---|
| Solubility | Short fructan chains dissolve readily in water. |
| Viscosity | A relatively low thickening contribution compared with high-molecular-weight gums. |
| Sweetness | Mild sweetness arises from short-chain carbohydrates and accompanying sugars. |
| Solids contribution | Powder and syrup forms increase the dissolved carbohydrate phase. |
| Acid response | Acidic heating can shorten the chains and change the sugar distribution. |
Applications
| Application | Ingredient role | Contribution to the product |
|---|---|---|
| Cultured dairy and alternatives | Fibre within the soluble solids | Composition and sweetness adjustment. |
| Beverages and nutrition powders | Readily soluble fibre | A dissolved rather than particulate fibre phase. |
| Bars | Fibre-containing binder solids | Changes to sweetness, cohesion and moisture balance. |
| Bakery fillings | Soluble bulk | Texture and carbohydrate-profile adjustment within the filling. |
Formulation behaviour
FOS and oligofructose distribute through the water phase. In concentrated products, their behaviour is linked to total solids, water availability and the other carbohydrates present. Syrups bring water as well as carbohydrate solids; powders alter the solids balance without the same added-water contribution.
Replacing part of a sugar system with fructan solids changes more than sweetness. Browning, water activity, crystallisation and freezing behaviour arise from the complete carbohydrate mixture. Acid exposure during heating can further change the composition through hydrolysis. These effects are particularly relevant in fruit preparations and products with extended hot holding.
Material forms
Sucrose-derived short-chain FOS and inulin-derived oligofructose have different production origins. Commercial powder and syrup preparations also differ in fibre concentration, residual sugars and water content. The chain-length distribution defines the fructan fraction; the ingredient's total dry solids include any accompanying carbohydrates.
Comparison with related ingredients
Long-chain inulin offers lower solubility and more structuring potential. GOS contains galactose-based oligosaccharides with a different source and linkage profile. Resistant dextrin supplies glucose-based soluble fibre with a different carbohydrate distribution and typically less sweetness contribution.