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lactose

lactose (lăk´tōs) or milk sugar, white crystalline disaccharide (see carbohydrate). It has the same empirical formula (C12H22O11) as sucrose (cane sugar) and maltose but differs from both in structure (see isomer). It yields the simple sugars D-glucose and D-galactose on hydrolysis, which is catalyzed by lactase, an enzyme found in gastric juice. People who lack this enzyme after childhood cannot digest milk and are said to be lactose intolerant. Lactose is formed in the mammary glands of all lactating animals and is present in their milk. It is produced commercially as a byproduct of milk processing. When milk sours, the lactose in it is converted by bacteria to lactic acid. Lactose is less sweet-tasting than sucrose and is not found in plants.

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lactose

lactose The carbohydrate of milk, sometimes called milk sugar. A disaccharide of glucose and galactose. Used pharmaceutically as a tablet filler and as a medium for growth of micro‐organisms. The fermentation of lactose to lactic acid by bacteria is responsible for the souring of milk. Ordinary lactose is α‐lactose, which is 16% as sweet as sucrose; if crystallized above 93 °C, it is converted to the β‐form which is more soluble and sweeter.

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lactose

lactose (milk sugar) Disaccharide present in milk, made up of a molecule of glucose linked to a molecule of galactose. It is important in cheesemaking, when lactic bacteria turn it into lactic acid. This sours the milk and results in the production of cheese curd.

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lactose

lactose (milk sugar) A sugar comprising one glucose molecule linked to a galactose molecule. Lactose is manufactured by the mammary gland and occurs only in milk. For example, cows' milk contains about 4.7% lactose. It is less sweet than sucrose (cane sugar).

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lactose

lactose (milk sugar) (lak-tohz) n. a sugar, consisting of one molecule of glucose and one of galactose, found only in milk. l. intolerance inability to absorb lactose, caused by absence or low activity of the enzyme lactase.

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lactose

lac·tose / ˈlakˌtōs; -ˌtōz/ • n. Chem. a sugar present in milk. It is a disaccharide containing glucose and galactose units.

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lactose

lactose (milk sugar) A disaccharide sugar comprising glucose and galactose; it is the principal sugar in milk.

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lactose

lactoseadiós, chausses, Close, Davos, dose, engross, gross, Grosz, jocose, morose, Rhos, verbose •grandiose • religiose • otiose •globose • viscose • bellicose • varicose •vorticose • cellulose • lachrymose •lactose • comatose • siliquose

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