lactose (redirected from lactose tolerance test)

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

Slightly sweet sugar (disaccharide) composed of two monosaccharides, glucose and galactose, linked together. Lactose-intolerant adults, and more rarely infants, cannot digest lactose because they lack the enzyme (lactase) that splits it into simpler sugars and suffer diarrhea and bloating when they eat foods containing it. Lactose, which makes up 2–8% of the milk of mammals, is the only common sugar of animal origin. Commercial lactose is obtained from whey, a liquid by-product of cheese. It is used in foods, in pharmaceuticals, and in nutrient broths used to produce penicillin, yeast, and riboflavin, and other products.

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lactose

a white crystalline disaccharide occurring in milk and used in the manufacture of pharmaceuticals and baby foods. Formula: C₁₂H₂₂O₁₁

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lactose [′lak‚tōs]

(biochemistry)

C₁₂H₂₂O₁₁A disaccharide composed ofD-glucose andD-galactose which occurs in milk. Also known as lactin; milk sugar.

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Lactose

Milk sugar or 4-O-β- d -galactopyranosyl- d -glucose. This reducing disaccharide is obtained as the α- d anomer (see formula, where the asterisk indicates a reducing group); the melting point is 202^°C (396^°F). Lactose is found in the milk of

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mammals to the extent of approximately 2–8%. It is usually prepared from whey, which is obtained by a by-product in the manufacture of cheese. Upon concentration of the whey, crystalline lactose is deposited.