Fructooligosaccharides also sometimes called oligofructose or oligofructan, are oligosaccharide
fructans, used as an alternative sweetener.
FOS exhibits sweetness levels between 30 and 50 percent of sugar in commercially prepared
syrups.
It occurs naturally, and its commercial use emerged in the 1980s in response to consumer
demand for healthier and calorie-reduced foods.
Chemistry Two different classes of fructooligosaccharide
mixtures are produced commercially, based on inulin degradation or transfructosylation
processes.
FOS can be produced by degradation of inulin, or polyfructose, a polymer of D-fructose residues
linked by β(2→1) bonds with a terminal α(1→2) linked D-glucose.
The degree of polymerization of inulin ranges from 10 to 60.
Inulin can be degraded enzymatically or chemically to a mixture of oligosaccharides with the
general structure Glu-Frun and Frum, with n and m ranging from 1 to 7.
This process also occurs to some extent in nature, and these oligosaccharides can be
found in a large number of plants, especially in Jerusalem artichoke, chicory and the Blue
Agave plant.
The main components of commercial products are kestose, nystose, fructosylnystose, bifurcose,
inulobiose, inulotriose, and inulotetraose.
The second class of FOS is prepared by the transfructosylation action of a β-fructosidase
of Aspergillus niger or Aspergillus aculeatus on sucrose.
The resulting mixture has the general formula of GFn, with n ranging from 1 to 5.
Contrary to the inulin-derived FOS, not only is there β(1→2) binding but other linkages
do occur, however, in limited numbers.
Because of the configuration of their glycosidic bonds, fructooligosaccharides resist hydrolysis
by salivary and intestinal digestive enzymes.
In the colon they are fermented by anaerobic bacteria.
In other words, they have a lower caloric value, while contributing to the dietary fiber
fraction of the diet.
Fructooligosaccharides are more soluble than inulins and are, therefore, sometimes used
as an additive to yogurt and other products.
Fructooligosaccharides are used specially in combination with high-intensity artificial
sweeteners, whose sweetness profile and aftertaste it improves.
Food sources FOS is extracted from the blue Agave plant
as well as fruits and vegetables such as bananas, onions, chicory root, garlic, asparagus, jícama,
and leeks.
Some grains and cereals, such as wheat and barley, also contain FOS.
The Jerusalem artichoke and its relative yacón together with the Blue Agave plant have been
found to have the highest concentrations of FOS of cultured plants.
Health benefits FOS has been a popular sweetner in Japan for
many years, even before 1990, when the Japanese government installed a "Functionalized Food
Study Committee" of 22 experts to start to regulate "special nutrition foods or functional
foods" that contain the categories of fortified foods, and is now becoming increasingly popular
in Western cultures for its prebiotic effects.
FOS serves as a substrate for microflora in the large intestine, increasing the overall
gastrointestinal tract health.
It has also been proposed as a supplement for treating yeast infections.
Several studies have found that FOS and inulin promote calcium absorption in both the animal
and the human gut.
The intestinal microflora in the lower gut can ferment FOS, which results in a reduced
pH.
Calcium is more soluble in acid, and, therefore, more of it comes out of food and is available
to move from the gut into the bloodstream.
FOS can be considered a small dietary fibre with low caloric value.
The fermentation of FOS results in the production of gases and acids.
The latter provide some energy to the body.
Side-effects All inulin-type prebiotics, including FOS,
are generally thought to stimulate the growth of Bifidobacteria species.
Bifidobacteria are considered beneficial bacteria.
This effect has not been uniformly found in all studies, both for Bifidobacteria and for
other gut organisms.
FOS are also fermented by numerous bacterial species in the intestine, including Klebsiella,
E. coli and many Clostridium species, which can be pathogenic in the gut.
These species are responsible mainly for the gas formation, which results after ingestion
of FOS.
Studies have shown that up to 20 grams/day is well tolerated.
Regulation US FDA regulation
FOS is classified as generally recognized as safe.
NZ FSANZ regulation The Food Safety Authority warned parents of
babies that a major European Baby-Formula brand made in New Zealand does not comply
with local regulations,) and urged them to stop using it.
EU regulation FOS use has been approved in the European
Union; allowing addition of FOS in restricted amounts to baby formula and follow-on formula.
Infant and follow-on formula products containing FOS have been sold in the EU since 1999.
Canadian regulations FOS is currently not approved for use in baby
formula.
See also Xylooligosaccharide
References