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Yogurt, drinking yogurt, and fermented dairy — soluble fiber with excellent dispersibility.
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Functional Ingredients · Prebiotic Fiber
Fructooligosaccharides (FOS)
Short-chain fructans with high water solubility and mild natural sweetness — a recognized prebiotic soluble dietary fiber for dairy, beverages, bakery, dietary supplements, and functional foods.
Prebiotic fiber with excellent solubility
FOS consists of short chains of fructose molecules linked by β-(2→1) glycosidic bonds. Compared with inulin, FOS has a shorter degree of polymerization — making it more soluble and slightly sweeter. It resists digestion in the small intestine and is selectively utilized by beneficial microorganisms in the large intestine.
FOS are short-chain fructans classified as soluble dietary fiber and naturally occurring prebiotics. Typical characteristics include non-digestible carbohydrate, mild natural sweetness, and high water solubility. Commercial FOS generally has a degree of polymerization ranging from 2 to 10 fructose units.
No. Both belong to the fructan family, but FOS has a shorter chain length (lower degree of polymerization) than inulin — making it generally more soluble and slightly sweeter.
Most commercial FOS is produced by enzymatic conversion of sucrose using food-grade fructosyltransferase enzymes. Some products are also obtained through controlled extraction from natural plant sources such as chicory root.
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Contact usScientific Overview
Short-chain prebiotic with versatile formulation properties
FOS increases dietary fiber content, contributes mild sweetness for sugar-reduction strategies, and provides excellent solubility for beverages and liquid formulations. Available as powder or syrup, it is widely used in yogurt, functional beverages, bakery products, dietary supplements, and confectionery worldwide.
Explore full specificationsPrebiotic
Dietary Fiber
DP 2–10
Short-Chain Fructan
High
Water Solubility
Mild
Natural Sweetness
Product specifications & applications
Explore chemical structure, manufacturing, functional properties, applications, and quality parameters for Fructooligosaccharides (FOS).
Introduction
Fructooligosaccharides (FOS) are short-chain fructans composed primarily of fructose molecules linked by β-(2→1) glycosidic bonds, usually terminating with a glucose molecule. They belong to the broader fructan family, which also includes inulin.
FOS is classified as a soluble dietary fiber and widely recognized as a prebiotic because it resists digestion in the small intestine and is selectively utilized by certain beneficial microorganisms in the large intestine.
Natural Sources
- Chicory root, onion, garlic, leek, asparagus
- Banana, wheat, Jerusalem artichoke
- Blue agave, yacon root
Although naturally present in foods, commercial quantities are generally produced through industrial manufacturing.
Chemical Structure
FOS consists primarily of fructose units with one terminal glucose molecule, connected by β-(2→1) glycosidic bonds resistant to human digestive enzymes. Because these linkages are not hydrolyzed in the small intestine, FOS reaches the large intestine largely intact.
Nutritional Characteristics
- Non-digestible carbohydrate
- Soluble fiber
- Fermentable by certain intestinal microorganisms
- Lower caloric contribution than digestible sugars
Scientific Summary
FOS are short-chain fructans classified as soluble dietary fiber and recognized as prebiotics. Produced primarily through enzymatic conversion of sucrose, FOS is widely used in dairy, beverages, bakery, dietary supplements, and functional foods for its high solubility, mild sweetness, and prebiotic properties.
Manufacturing Process
Enzymatic Conversion from Sucrose (Most Common)
- Preparation — Food-grade sucrose solution prepared
- Enzymatic Reaction — Fructosyltransferases convert sucrose into FOS through transfructosylation
- Purification — Membrane filtration, activated carbon treatment, ion exchange to remove residual sugars and impurities
- Concentration — Purified FOS solution concentrated under controlled conditions
- Drying — Supplied as powder or syrup
Extraction from Natural Sources
Some FOS products are obtained through controlled extraction from plants such as chicory root, although enzymatic production is more common for industrial-scale manufacturing.
Functional Properties
Soluble Fiber Enrichment
Increases dietary fiber content in foods and beverages.
Mild Sweetness
Compared with inulin, FOS has naturally mild sweetness that can contribute to product formulation and sugar-reduction strategies.
High Water Solubility
Excellent solubility suitable for beverages, dairy products, syrups, and nutritional supplements.
Texture Improvement
Contributes body and mouthfeel in selected food applications.
Sugar Reduction Support
Can contribute bulk and sweetness in reduced-sugar formulations when used as part of an overall product design.
Prebiotic Function
FOS passes through the small intestine without significant digestion and serves as a fermentable substrate for certain beneficial microorganisms in the large intestine. Degree of fermentation varies according to individual gut microbiota, dietary intake, quantity consumed, and overall nutritional status.
Food Applications
Dairy Products
Yogurt, drinking yogurt, fermented dairy products, and dairy desserts — soluble dietary fiber with good dispersibility.
Beverages
Functional beverages, protein drinks, nutritional beverages, and meal replacement drinks — high solubility ideal for liquid formulations.
Bakery Products
Bread, cakes, muffins, biscuits, and cookies — dietary fiber with texture support.
Nutritional Supplements
Fiber supplements, powdered nutrition products, functional nutrition blends, and prebiotic supplements.
Infant Nutrition
In some jurisdictions, FOS is used in infant formula and young child nutrition products where permitted by applicable regulations.
Confectionery
Gummies, nutrition bars, chocolate products, and functional confectionery.
Industrial Applications
Nutraceutical products, dietary supplements, functional ingredient blends, medical nutrition, and pharmaceutical formulations.
Quality & Storage
Storage Conditions
- Cool, dry environment
- Tightly sealed packaging
- Protected from moisture
- Away from direct sunlight
- According to manufacturer recommendations
Proper storage helps maintain product quality and stability.
Quality Parameters
Commercial FOS is evaluated for FOS content, moisture content, appearance, particle size, solubility, microbiological quality, heavy metals, and food safety compliance.
Regulatory Considerations
Commercial FOS should comply with regulations governing food ingredients, dietary fiber labeling, food safety, GMP, microbiological standards, and contaminant limits.
Advantages
- Naturally occurring soluble dietary fiber
- Recognized prebiotic ingredient
- High water solubility
- Mild natural sweetness
- Suitable for vegetarian and vegan formulations
- Compatible with dairy, beverages, bakery, and nutritional products
- Supports reduced-sugar product development
- Available in powder and syrup forms
- Broad application across food and nutrition industries
Where FOS performs best
High solubility and prebiotic fiber enrichment across dairy, beverages, and supplements.
Beverages
Functional drinks, protein beverages, and meal replacements — ideal for liquid formulations.
Explore beveragesDietary Supplements
Fiber supplements, prebiotic blends, and powdered nutrition products.
Explore nutritionFOS at a glance
Structure
Short-chain fructan (DP 2–10) with β-(2→1) glycosidic bonds — more soluble and sweeter than long-chain inulin.
Forms
Available as powder or syrup — both widely used in food manufacturing for different formulation requirements.
Prebiotic
Reaches the large intestine intact where it serves as fermentable substrate for beneficial gut microorganisms.
Related functional ingredients
Inulin
Explore inulin
Resistant Dextrin
Explore resistant dextrin
Polydextrose
Explore polydextrose
What are Fructooligosaccharides (FOS)?
Read the full guide
Soluble Dietary Fiber
Read the full guideFrequently asked questions
Fructooligosaccharides are short-chain fructans composed mainly of fructose molecules and classified as soluble dietary fiber.
No. Both belong to the fructan family, but FOS has a shorter chain length than inulin, making it generally more soluble and slightly sweeter.
Most commercial FOS is produced by enzymatic conversion of sucrose using food-grade fructosyltransferase enzymes. Some products are also obtained from natural plant sources.
FOS is not digested in the small intestine and can be selectively utilized by certain beneficial microorganisms in the large intestine.
Yogurt, beverages, bakery products, nutritional supplements, meal replacements, confectionery, and other functional food products.
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