Fructan
Encyclopedia
A fructan is a polymer
Polymer
A polymer is a large molecule composed of repeating structural units. These subunits are typically connected by covalent chemical bonds...

 of fructose
Fructose
Fructose, or fruit sugar, is a simple monosaccharide found in many plants. It is one of the three dietary monosaccharides, along with glucose and galactose, that are absorbed directly into the bloodstream during digestion. Fructose was discovered by French chemist Augustin-Pierre Dubrunfaut in 1847...

 molecules. Fructans with a short chain length are known as fructooligosaccharides
Fructooligosaccharide
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...

, whereas longer chain fructans are termed inulins
Inulin
Inulins are a group of naturally occurring polysaccharides produced by many types of plants. They belong to a class of fibers known as fructans. Inulin is used by some plants as a means of storing energy and is typically found in roots or rhizomes...

. Fructans occur in foods such as agave
Agave
Agave is a genus of monocots. The plants are perennial, but each rosette flowers once and then dies ; they are commonly known as the century plant....

, artichoke
Artichoke
-Plants:* Globe artichoke, a partially edible perennial thistle originating in southern Europe around the Mediterranean* Jerusalem artichoke, a species of sunflower with an edible tuber...

s, asparagus
Asparagus
Asparagus officinalis is a spring vegetable, a flowering perennialplant species in the genus Asparagus. It was once classified in the lily family, like its Allium cousins, onions and garlic, but the Liliaceae have been split and the onion-like plants are now in the family Amaryllidaceae and...

, leeks, garlic
Garlic
Allium sativum, commonly known as garlic, is a species in the onion genus, Allium. Its close relatives include the onion, shallot, leek, chive, and rakkyo. Dating back over 6,000 years, garlic is native to central Asia, and has long been a staple in the Mediterranean region, as well as a frequent...

, onion
Onion
The onion , also known as the bulb onion, common onion and garden onion, is the most widely cultivated species of the genus Allium. The genus Allium also contains a number of other species variously referred to as onions and cultivated for food, such as the Japanese bunching onion The onion...

s (including spring onions), yacon
Yacón
The Yacón is a perennial plant traditionally grown in the Northern and Central Andes from Ecuador to Argentina for its crisp, sweet-tasting tuberous roots. The texture and flavour are very similar to jicama mainly differing in that yacon has some slightly sweet resinous and floral undertones to...

, jícama
Jícama
Pachyrhizus erosus, commonly known as Jícama , Yam, and Mexican Turnip, is the name of a native Mexican vine, although the name most commonly refers to the plant's edible tuberous root. Jícama is one species in the genus Pachyrhizus. Plants in this genus are commonly referred to as yam bean,...

, and wheat
Wheat
Wheat is a cereal grain, originally from the Levant region of the Near East, but now cultivated worldwide. In 2007 world production of wheat was 607 million tons, making it the third most-produced cereal after maize and rice...

.

In animal fodder
Fodder
Fodder or animal feed is any agricultural foodstuff used specifically to feed domesticated livestock such as cattle, goats, sheep, horses, chickens and pigs. Most animal feed is from plants but some is of animal origin...

, fructans also appear in grass
Grass
Grasses, or more technically graminoids, are monocotyledonous, usually herbaceous plants with narrow leaves growing from the base. They include the "true grasses", of the Poaceae family, as well as the sedges and the rushes . The true grasses include cereals, bamboo and the grasses of lawns ...

, with dietary implications for horses and other equidae
Equidae
Equidae is the taxonomic family of horses and related animals, including the extant horses, donkeys, and zebras, and many other species known only from fossils. All extant species are in the genus Equus...

.

Functions

Plants storing their food as fructans are able to thrive at low temperatures since fructans confer tolerance to freezing.
They bind to membranes, thereby helping to keep cells intact.

Fructan content of various foods

Artichoke, Jerusalem
Jerusalem artichoke
The Jerusalem artichoke , also called the sunroot, sunchoke, earth apple or topinambour, is a species of sunflower native to eastern North America, and found from Eastern Canada and Maine west to North Dakota, and south to northern Florida and Texas...

16.0-20.0%
Artichoke, Globe
Globe artichoke
The globe artichoke is a perennial thistle of the Cynara genus originating in Southern Europe around the Mediterranean. It grows to tall, with arching, deeply lobed, silvery, glaucous-green leaves long. The flowers develop in a large head from an edible bud about diameter with numerous...

2.0-6.8%
Asparagus
Asparagus
Asparagus officinalis is a spring vegetable, a flowering perennialplant species in the genus Asparagus. It was once classified in the lily family, like its Allium cousins, onions and garlic, but the Liliaceae have been split and the onion-like plants are now in the family Amaryllidaceae and...

1.4-4.1%
Barley kernels (very young) 22%
Cheese spread 4.5%
Chocolate
Chocolate
Chocolate is a raw or processed food produced from the seed of the tropical Theobroma cacao tree. Cacao has been cultivated for at least three millennia in Mexico, Central and South America. Its earliest documented use is around 1100 BC...

9.4%
Garlic
Garlic
Allium sativum, commonly known as garlic, is a species in the onion genus, Allium. Its close relatives include the onion, shallot, leek, chive, and rakkyo. Dating back over 6,000 years, garlic is native to central Asia, and has long been a staple in the Mediterranean region, as well as a frequent...

17.4%
Onion
Onion
The onion , also known as the bulb onion, common onion and garden onion, is the most widely cultivated species of the genus Allium. The genus Allium also contains a number of other species variously referred to as onions and cultivated for food, such as the Japanese bunching onion The onion...

1.1-10.1%
Pasta 1-4%
Rye (bran) 7%
Rye (grain)
Rye
Rye is a grass grown extensively as a grain and as a forage crop. It is a member of the wheat tribe and is closely related to barley and wheat. Rye grain is used for flour, rye bread, rye beer, some whiskeys, some vodkas, and animal fodder...

4.6-6.6%
Wheat flour 1-4%
White bread 0.7-2.8%

See also

  • Fructose intolerance
    Fructose intolerance
    Hereditary fructose intolerance or fructose poisoning is a hereditary condition caused by a deficiency of liver enzymes that metabolise fructose...

  • Fructose malabsorption
    Fructose malabsorption
    Fructose malabsorption, formerly named "dietary fructose intolerance," is a digestive disorder in which absorption of fructose is impaired by deficient fructose carriers in the small intestine's enterocytes. This results in an increased concentration of fructose in the entire intestine.Fructose...

  • Glucan
    Glucan
    A glucan molecule is a polysaccharide of D-glucose monomers linked by glycosidic bonds.Many beta-glucans are medically important.-Types:The following are glucans:-Alpha:...

  • Prebiotic (nutrition)
    Prebiotic (nutrition)
    Prebiotics are non-digestible food ingredients that stimulate the growth and/or activity of bacteria in the digestive system in ways claimed to be beneficial to health. They were first identified and named by Marcel Roberfroid in 1995. As a functional food component, prebiotics, like probiotics,...

  • Sucrose
    Sucrose
    Sucrose is the organic compound commonly known as table sugar and sometimes called saccharose. A white, odorless, crystalline powder with a sweet taste, it is best known for its role in human nutrition. The molecule is a disaccharide composed of glucose and fructose with the molecular formula...

  • Levan polysaccharide
    Levan polysaccharide
    Levan, a homopolysaccharide which is composed of D-fructofuranosyl residues joined by 2,6 with multiple branches by 2,1 linkages has great potential as a functional biopolymer in foods, feeds, cosmetics, and the pharmaceutical and chemical industries. Levan can be used as food or a feed additive...


General references

  • Sugar - Chemical, Biological and Nutritional Aspects of Sucrose. John Yudkin, Jack Edelman and Leslie Hough (1971, 1973). The Butterworth Group. ISBN 0-408-70172-2
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