Fructooligosaccharides
[CAS# 308066-66-2]

Identification

• Classification: Biochemical >> Carbohydrate >> Double sugar
• Name: Fructooligosaccharides
• Synonyms: �-D-Fructofuranose; (2R,3S,4S,5R)-2,5-bis(hydroxymethyl)oxolane-2,3,4-triol; Oligosaccharides, fructose-contg.; Actilight; Beneo OPS; Beneo P 95; FOS-P Power 300; FortiFeed; FortiFeed P 95; Fructose-containing oligosaccharides; Fructose-contg. oligosaccharides; NutraFlora; NutraFlora L 55; NutraFlora L 95; NutraFlora P 95; NutraFlora scFOS; Nutriflora P; Orafti L 85; Raftilose Synergy; scFOS
• Molecular Formula: C₆H₁₂O₆
• Molecular Weight: 180.16
• CAS Registry Number: 308066-66-2
• SMILES: C([C@@H]1[C@H]([C@@H]([C@](O1)(CO)O)O)O)O

Properties

• Density: 1.7±0.1 g/cm³ Calc.^*, 1.59 g/mL (Expl.)
• Melting point: 105 - 110 ºC (Expl.)
• Boiling point: 440.1±45.0 ºC 760 mmHg (Calc.)^*
• Flash point: 220.0±28.7 ºC (Calc.)^*
• Index of refraction: 1.617 (Calc.)^*

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software.

Discovory and Applicatios

Fructooligosaccharides (FOS) are short-chain carbohydrates composed of fructose units linked by β(2–1) glycosidic bonds and typically terminated by a glucose residue. They occur naturally in many plants, including chicory roots, Jerusalem artichokes, onions, garlic, bananas, and asparagus. The discovery of FOS dates back to early carbohydrate research in the 1930s, when chemists first isolated inulin-type fructans and identified their oligosaccharide components. Later, advances in enzymatic synthesis allowed for the controlled production of specific FOS molecules, which greatly enhanced their commercial availability and study.

Industrial production of FOS generally involves the enzymatic transfructosylation of sucrose using β-fructofuranosidase or fructosyltransferase enzymes derived from microorganisms such as *Aspergillus niger*, *Aureobasidium pullulans*, or *Bacillus subtilis*. The process yields mixtures of oligosaccharides containing three to five fructose units, commonly referred to as 1-kestose, nystose, and fructofuranosylnystose. These molecules are water-soluble, mildly sweet, and non-cariogenic, making them valuable as functional ingredients in food and pharmaceutical formulations.

One of the most important applications of FOS lies in their function as prebiotics. They are selectively fermented by beneficial gut bacteria, particularly *Bifidobacterium* and *Lactobacillus* species, promoting intestinal health and improving microbial balance. Numerous clinical and animal studies have demonstrated that FOS consumption can enhance short-chain fatty acid production, improve mineral absorption (especially calcium and magnesium), and modulate lipid metabolism. Because they are non-digestible by human enzymes, FOS contribute minimal caloric content while improving intestinal transit and stool quality.

In the food industry, FOS are widely used as low-calorie sweeteners and texturizing agents. Their mild sweetness, about 30–50% that of sucrose, allows partial sugar replacement in beverages, yogurts, bakery products, and dietary supplements without compromising taste. In addition, their hygroscopic nature and water-binding capacity help improve moisture retention in baked goods and dairy applications. FOS are also incorporated into infant formulas to mimic the functional properties of human milk oligosaccharides, supporting the establishment of healthy gut flora in infants.

Pharmaceutical and nutraceutical applications of FOS continue to expand. Research has shown potential benefits in reducing serum cholesterol, enhancing immune function, and lowering risks associated with colon cancer due to increased production of butyrate and other beneficial metabolites. Moreover, FOS are being investigated as carriers for controlled drug delivery systems due to their fermentability and compatibility with intestinal microflora.

Commercial production of FOS has become an established industry, with enzymatic processes optimized for high yield and purity. Some production systems use immobilized enzyme reactors to increase efficiency and enzyme stability. The main commercial forms are syrups and powders standardized for total FOS content, often combined with other dietary fibers to create functional blends for health-oriented food products. The global market for FOS is projected to continue growing as consumer demand for natural prebiotic ingredients increases.

Research on FOS is also focusing on structure–function relationships to better understand how chain length and linkage patterns influence fermentation profiles and physiological effects. Emerging biotechnological methods, including the use of genetically engineered microbial strains, are enabling more efficient production routes and the creation of tailor-made oligosaccharides with specific prebiotic functions. Such innovations promise to expand their range of applications in nutrition, health care, and even environmental biotechnology.

References

2003. Synergistic Responses of the Chorda Tympani to Mixtures of Umami and Sweet Substances in Rats. Chemical Senses, 28(3).
DOI: 10.1093/chemse/28.3.261

2003. Topiramate induced myopic shift and angle closure glaucoma. The British Journal of Ophthalmology, 87(5).
DOI: 10.1136/bjo.87.5.648

2003. Tubular injury: the first symptom of hypertensive kidney involvement? Medical Science Monitor.
DOI: 12709672