Raffinose is a trisaccharide 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 molecu ...

glucose Glucose is a simple sugar with the molecular formula . Glucose is overall the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, u ...

, and fructose. It can be found in beans, cabbage,

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 cabbages ...

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 cla ...

asparagus Asparagus, or garden asparagus, folk name sparrow grass, scientific name ''Asparagus officinalis'', is a perennial flowering plant species in the genus '' Asparagus''. Its young shoots are used as a spring vegetable. It was once classified in ...

, 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, stac ...

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

Chemical properties

The raffinose family of

oligosaccharide An oligosaccharide (/ˌɑlɪgoʊˈsækəˌɹaɪd/; from the Greek ὀλίγος ''olígos'', "a few", and σάκχαρ ''sácchar'', "sugar") is a saccharide polymer containing a small number (typically two to ten) of monosaccharides (simple sug ...

s (RFOs) are alpha-galactosyl derivatives of sucrose, and the most common are the trisaccharide 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 Gala ...

, and the pentasaccharide verbascose. RFOs are almost ubiquitous in the

plant Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae exclu ...

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 ...

animals ( pigs and

poultry Poultry () are domesticated birds kept by humans for their eggs, their meat or their feathers. These birds are most typically members of the superorder Galloanserae (fowl), especially the order Galliformes (which includes chickens, quails, ...

) 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 ...

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typically a few micrometr ...

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 ''Streptococcus pneumoniae'', or pneumococcus, is a Gram-positive, spherical bacteria, alpha-hemolytic (under aerobic conditions) or beta-hemolytic (under anaerobic conditions), aerotolerant anaerobic member of the genus Streptococcus. They ar ...

'', impacts their ability to cause disease and the nature of the disease.

Uses

Procedures concerning cryopreservation have used raffinose to provide hypertonicity 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