Dietary fiber

thumb|Green tea-flavored yōkan, a popular Japanese red bean jelly made from agar thumb|A blood agar plate used to culture bacteria and diagnose infection

indigestible portion of food derived from plants

thumb|500px|Idealized structure of lignin from a softwood Lignin is a class of complex organic polymers that form key structural materials in the support tissues of most plants. Lignins are particularly important in the formation of cell walls, especially in wood and bark, because they lend rigidity and do not rot easily. Chemically, lignins are polymers made by the cross-linking of phenolic precursors.

thumb|Commercially produced powder of pectin, extracted from citrus fruits Pectin ( : 'congealed' and 'curdled') is a heteropolysaccharide, a structural polymer contained in the cell walls and middle lamellae of terrestrial plants. The principal chemical component of pectin is galacturonic acid (a sugar acid derived from galactose) which was isolated and described by Henri Braconnot in 1825. Commercially produced pectin is a white-to-light-brown powder, produced from citrus fruits for use as an edible gelling agent, especially in jams and jellies, dessert fillings, medications, and sweets; as

Inulins are a group of naturally occurring polysaccharides produced by many types of plants, industrially most often extracted from chicory. Inulin is used by some plants as a means of storing energy and is typically found in roots or rhizomes. Most plants that synthesize and store inulin do not store other forms of carbohydrate such as starch.

Xylose ( , , "wood") is a common monosaccharide, i.e. a simple sugar. Xylose is classified as aldopentose type, which means that it contains five carbon atoms and includes an aldehyde functional group, at least in its open-chain form. It is abundant in biomass, and is one of the most abundant sugars in nature. It is a white, water-soluble solid.

Lactulose is a non-absorbable sugar used in the treatment of constipation and hepatic encephalopathy. It is administered orally for constipation, and either orally or rectally for hepatic encephalopathy. It generally begins working after 8–12 hours, but may take up to 2 days to improve constipation.

A hemicellulose (also known as polyose) is one of a number of heteropolymers (matrix polysaccharides), such as arabinoxylans, present along with cellulose in almost all terrestrial plant cell walls. Cellulose is crystalline, strong, and resistant to hydrolysis. Hemicelluloses are branched, shorter in length than cellulose, and also show a propensity to crystallize. They can be hydrolyzed by dilute acid or base as well as a myriad of hemicellulase enzymes.

thumb|Underwater Eucheuma farming in the [[Philippines for carrageenan production]] Carrageenans or carrageenins ( ; ) are a family of natural linear sulfated polysaccharides. They are extracted from red edible seaweeds. Carrageenans are widely used in the food industry for their gelling, thickening, and stabilizing properties. Their main application is in dairy and meat products, due to their strong binding to food proteins. Carrageenans have emerged as a promising candidate in tissue engineering and regenerative medicine applications as they resemble animal glycosaminoglycans (GAGs). They ar

Raffinose is a trisaccharide derived from galactose, glucose, and fructose. Raffinose can be hydrolyzed to D-galactose and sucrose by the enzyme alpha galactosidase (α-GAL), an enzyme synthesized by bacteria found in the large intestine. α-GAL also hydrolyzes other alpha galactosides such as stachyose, verbascose, and galactinol, if present. In plants, raffinose plays a significant role in stress responses, particularly temperature sensitivity, seed vigour, resistance to pathogens, and desiccation. It can be found in beans, cabbage, Brussels sprouts, broccoli, asparagus, other vegetables, and

polysaccharide found in brown algae

thumb|Gummy bears made with polydextrose Polydextrose is a synthetic polymer of glucose. It is a food ingredient classified as soluble fiber by the US FDA as well as Health Canada, . It is frequently used to increase the dietary fiber content of food, to replace sugar, and to reduce calories and fat content. It is a multi-purpose food ingredient synthesized from dextrose (glucose), plus about 10 percent sorbitol and 1 percent citric acid. Its E number is E1200. The FDA approved it in 1981.

Lichenin, also known as lichenan or moss starch, is a complex glucan occurring in certain species of lichens and grains. It can be extracted from Cetraria islandica (Iceland moss). It has been studied since about 1957.

Arabinoxylan is a form of the hemicellulose xylan found in both the primary and secondary cell walls of plants which in addition to xylose contains substantial amounts of another pentose sugar, arabinose. The term arabinoxylan usually refers to feruloyl-arabinoxylan from grasses and other commelinids containing moieties of the phenolic ferulic acid that can undergo oxidative coupling (in the same way as lignin units) forming crosslinks between arabinoxylan chains and with lignin. Whilst arabinose has been found linked to xylan in non-commelinid plants, ferulic acid has not been reported on the