Category: sugar
Aliases: Malt sugar, Maltobiose, D-Maltose, α-Maltose, 4-O-α-D-glucopyranosyl-D-glucose
A reducing disaccharide of two α-D-glucose units joined by an α-1,4-glycosidic bond, released from starch and glycogen by salivary and pancreatic α-amylase. Maltose is not absorbed intact: brush-border maltase-glucoamylase and sucrase-isomaltase hydrolyse it to two molecules of [[glucose]], which enter enterocytes via SGLT1 and exit basolaterally through GLUT2, raising portal glucose and provoking an [[insulin]] response comparable to free glucose (high glycemic index). It thus behaves metabolically as a glucose pro-source rather than a distinct sugar, feeding glycolysis, glycogenesis and the pentose-phosphate pathway. Roughly a third as sweet as sucrose, it is a nutritive caloric carbohydrate (~4 kcal/g) common in malt, beer wort and starch syrups; with no specialized intestinal transporter, malabsorption is rare relative to lactose or fructose.