Raffinose is a

trisaccharide ''Trisaccharides'' are oligosaccharides composed of three monosaccharides with two glycosidic bonds connecting them. Similar to the disaccharides, each glycosidic bond can be formed between any hydroxyl group on the component monosaccharides. Even ...

composed of

galactose Galactose (, '' galacto-'' + ''-ose'', "milk sugar"), sometimes abbreviated Gal, is a monosaccharide sugar that is about as sweet as glucose, and about 65% as sweet as sucrose. It is an aldohexose and a C-4 epimer of glucose. A galactose molec ...

, glucose, and

fructose Fructose, or fruit sugar, is a ketonic simple sugar found in many plants, where it is often bonded to glucose to form the disaccharide sucrose. It is one of the three dietary monosaccharides, along with glucose and galactose, that are absorbe ...

. It can be found in

bean A bean is the seed of several plants in the family Fabaceae, which are used as vegetables for human or animal food. They can be cooked in many different ways, including boiling, frying, and baking, and are used in many traditional dishes thr ...

cabbage Cabbage, comprising several cultivars of ''Brassica oleracea'', is a leafy green, red (purple), or white (pale green) biennial plant grown as an annual vegetable crop for its dense-leaved heads. It is descended from the wild cabbage ( ''B.&nbs ...

brussels sprout The Brussels sprout is a member of the Gemmifera cultivar group of cabbages (''Brassica oleracea''), grown for its edible buds. The leaf vegetables are typically 1.5–4.0 cm (0.6–1.6 in) in diameter and resemble miniature cabbage ...

broccoli Broccoli (''Brassica oleracea'' var. ''italica'') is an edible green plant in the cabbage family (family Brassicaceae, genus ''Brassica'') whose large flowering head, stalk and small associated leaves are eaten as a vegetable. Broccoli is cl ...

, asparagus, other vegetables, and whole grains. Raffinose can be hydrolyzed to D-galactose and sucrose by the enzyme α-galactosidase (α-GAL), an enzyme which in the lumen of the human digestive tract is only produced by bacteria in the large intestine. α-GAL also hydrolyzes other α-galactosides such as

stachyose Stachyose is a tetrasaccharide consisting of two α--galactose units, one α--glucose unit, and one β--fructose unit sequentially linked as gal(α1→6)gal(α1→6)glc(α1↔2β)fru. Together with related oligosaccharides such as raffinose, stach ...

, verbascose, and galactinol, if present. The enzyme does not cleave β-linked galactose, as in lactose.

Chemical properties

The raffinose family of oligosaccharides (RFOs) are alpha-galactosyl derivatives of sucrose, and the most common are the

raffinose, the

tetrasaccharide A tetrasaccharide is a carbohydrate which gives upon hydrolysis four molecules of the same or different monosaccharides. For example, stachyose upon hydrolysis gives one molecule each of glucose and fructose and two molecules of galactose Gal ...

, and the pentasaccharide verbascose. RFOs are almost ubiquitous in the plant kingdom, being found in a large variety of seeds from many different families, and they rank second only to sucrose in abundance as

soluble carbohydrates In chemistry, solubility is the ability of a substance, the solute, to form a solution with another substance, the solvent. Insolubility is the opposite property, the inability of the solute to form such a solution. The extent of the solubil ...

. Raffinose may have a form of a white crystalline powder. It is odorless and has a sweet taste approximately 10% that of sucrose.

Biochemical properties

Energy source

It is non-digestible in humans and other

monogastric A monogastric organism has a simple single-chambered stomach (one stomach). Examples of monogastric herbivores are horses and rabbits. Examples of monogastric omnivores include humans, pigs, hamsters and rats. Furthermore, there are monogastric ca ...

animals (

pig The pig (''Sus domesticus''), often called swine, hog, or domestic pig when distinguishing from other members of the genus '' Sus'', is an omnivorous, domesticated, even-toed, hoofed mammal. It is variously considered a subspecies of ''Sus s ...

s and poultry) who do not possess the α-GAL enzyme to break down RFOs. These oligosaccharides pass undigested through the stomach and small intestine. In the large intestine, they are

fermented Fermentation is a metabolic process that produces chemical changes in organic substrates through the action of enzymes. In biochemistry, it is narrowly defined as the extraction of energy from carbohydrates in the absence of oxygen. In food p ...

by bacteria that do possess the α-GAL enzyme and make short-chain fatty acids (SCFA)(acetic, propionic, butyric acids), as well as the flatulence commonly associated with eating beans and other vegetables. These SCFAs have been recently found to impart a number of health benefits. α-GAL is present in digestive aids such as the product Beano.

Disease relevance

Research has shown that the differential ability to utilize raffinose by strains of the bacteria '' Streptococcus pneumoniae'', impacts their ability to cause disease and the nature of the disease.

Uses

Procedures concerning cryopreservation have used raffinose to provide

hypertonicity In chemical biology, tonicity is a measure of the effective osmotic pressure gradient; the water potential of two solutions separated by a partially-permeable cell membrane. Tonicity depends on the relative concentration of selective membrane- ...

for cell desiccation prior to freezing. Either raffinose or sucrose is used as a base substance for sucralose. Raffinose is also used in: * skin moisturizers and smoothers * prebiotics (it promotes growth of lactobacilli and bifidobacteria) * food or drinks additive

References

{{Carbohydrates Trisaccharides