Combinations of more than two sugars are often referred to as oligosaccharides, unless they are very large and then they are called polysaccharides.
Raffinose and stachyose are two oligosaccharides of interest because they are hard to digest.
Raffinose contains one molecule each of glucose, fructose and galactose. Stachyose is very similar to raffinose except it contains two molecules of galactose.
Polysaccharides, also called glycans, consist of monosaccharides and their derivatives. If a polysaccharides contains only one kind of monosaccharides molecule, it is homopolysaccharides or homoglycan, whereas those containing more than one kind is monosaccharide are heteropolysaccharides.
In human, polysaccharides function as storage materials, structural components, or protective substances. This starch, glycogen and other storage polysaccharides, as readily ,metabolized food, provide energy reserves for cells.
Polysaccharides may be added to foods for a variety of reasons. Nutritionally, they are generally added to increase the dietary fiber content.
Functionally, polysaccharides are added to thicken, form gels, bond water and stabilize proteins.
Agarose and carrageenan can be used to produce gels. Agarose has been used in microbiology for more than 100 years to reinforce culture media (“agar-agar”).
Starch is the most common polysaccharides added to food products. For some uses, starch may chemically modified to improve stability or to alter its functional properties.
Inulin, a fructose polymer is used as a starch substitute in diabetics; dietary products. It also serves as a test substance for measuring renal clearance.
Cellulose and cellulose derivatives are also added to a number of food products. The term “gum” is used to describe some do the naturally occurring polysaccharides added to food.
Chitin, is the most important structural substance in insect ad crustacean shells, and is this the most common animal polysaccharides.
Some naturally occurring polysaccharides added to foods include: agar, gum tragacanth, algin, locust bean gum, carrageenan, starch, cellulose, pectin, guar gum, xanthan gum, and gum arabic.
Polysaccharides