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Lactose

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**1. Chemical Properties and Structure of Lactose:**
– Lactose is a disaccharide composed of glucose and galactose.
– Its systematic name is β-galactopyranosyl-(1→4)-glucose.
– Lactose is less sweet than sucrose and is soluble in water.
– It undergoes hydrolysis to break down into its monosaccharide components.
– The enzyme lactase is required to break down lactose in the digestive system.

**2. Occurrence, Isolation, and Industrial Uses of Lactose:**
– Lactose makes up about 2–8% of milk by weight.
– Several million tons of lactose are produced annually as a by-product of the dairy industry.
– Whey, containing 4.8% lactose, is purified by crystallisation.
– Lactose is used in the pharmaceutical industry as a filler in tablets.
– It is also utilized in the food industry for its sweetening properties and in the production of certain cheeses.

**3. Metabolism and Health Effects of Lactose:**
– Infant mammals produce lactase to digest lactose in milk.
– Lactase production decreases with maturity due to weaning.
– Over 70% of western Europeans can digest lactose as adults.
– Lactose intolerance can lead to gastrointestinal symptoms like bloating and diarrhea.
– Lactose-free products are available for those with lactose intolerance.

**4. Biological Properties and Applications of Lactose:**
– Lactose has a sweetness index of 0.2 to 0.4 and a caloric value of 4 kcal/g when fully digested.
– Undigested lactose acts as dietary fiber and aids in mineral absorption.
– Lactose is used as a carrier and stabilizer for aromas and pharmaceutical products.
– It is essential in infant formula to match human milk composition.
– Lactose is used in tablet and capsule drug products for its properties.

**5. Sources, Historical Significance, and Detection Reactions of Lactose:**
– Sources of lactose include dairy products, processed foods, medications, and supplements.
– Lactose was first isolated from milk in the 18th century.
– Scientists like Carl Wilhelm Scheele and Emil Fischer made significant contributions to understanding lactose.
– The configuration of glucose and galactose was determined by Fischer.
– Detection reactions for lactose include the Woehlk and Fearons test.

Lactose (Wikipedia)

Lactose, or milk sugar, is a disaccharide sugar composed of galactose and glucose subunits and has the molecular formula C12H22O11. Lactose makes up around 2–8% of milk (by mass). The name comes from lact (gen. lactis), the Latin word for milk, plus the suffix -ose used to name sugars. The compound is a white, water-soluble, non-hygroscopic solid with a mildly sweet taste. It is used in the food industry.

Lactose
Names
IUPAC name
β-D-Galactopyranosyl-(1→4)-D-glucose
Systematic IUPAC name
(2R,3R,4S,5R,6S)-2-(Hydroxymethyl)-6-{[(2R,3S,4R,5R,6R)-4,5,6-trihydroxy-2-(hydroxymethyl)oxan-3-yl]oxy}oxane-3,4,5-triol
Other names
Milk sugar
Lactobiose
4-O-β-D-Galactopyranosyl-D-glucose
Identifiers
3D model (JSmol)
90841
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.000.509 Edit this at Wikidata
EC Number
  • 200-559-2
342369
KEGG
UNII
  • InChI=1S/C12H22O11/c13-1-3-5(15)6(16)9(19)12(22-3)23-10-4(2-14)21-11(20)8(18)7(10)17/h3-20H,1-2H2/t3-,4-,5+,6+,7-,8-,9-,10-,11-,12+/m1/s1 checkY
    Key: GUBGYTABKSRVRQ-DCSYEGIMSA-N checkY
  • InChI=1/C12H22O11/c13-1-3-5(15)6(16)9(19)12(22-3)23-10-4(2-14)21-11(20)8(18)7(10)17/h3-20H,1-2H2/t3-,4-,5+,6+,7-,8-,9-,10-,11-,12+/m1/s1
    Key: GUBGYTABKSRVRQ-DCSYEGIMBP
  • C([C@@H]1[C@@H]([C@@H]([C@H]([C@@H](O1)O[C@@H]2[C@H](O[C@H]([C@@H]([C@H]2O)O)O)CO)O)O)O)O
Properties
C12H22O11
Molar mass 342.297 g·mol−1
Appearance White solid
Density 1.525 g/cm3
Melting point 252 °C (anhydrous)
202 °C (monohydrate)
195 g/L
+55.4° (anhydrous)
+52.3° (monohydrate)
Thermochemistry
5652 kJ/mol, 1351 kcal/mol, 16.5 kJ/g, 3.94 kcal/g
Hazards
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 0: Exposure under fire conditions would offer no hazard beyond that of ordinary combustible material. E.g. sodium chlorideFlammability 0: Will not burn. E.g. waterInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
0
0
0
Flash point 357.8 °C (676.0 °F; 631.0 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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