Lactose is disaccharide. This is a sugar consisting of galactose and glucose. Lactose forms about 2-8% milk (by weight). The name comes from lac (gen. lactis ), the Latin word for milk, plus the suffix -any is used for the sugar name. This compound is white, soluble in water, non-hygroscopic solid with a slightly sweet taste. It is used in the food industry.
Video Lactose
Struktur dan reaksi
Lactose is a disaccharide derived from the condensation of galactose and glucose, which forms a bond of -1-> 4 glycosidic. The systematic name is? - D -galactopyranosyl- (1-> 4) - D -glucose. Glucose can be either a pythonic-type or form-form, whereas galactose can only have the form-type: then? -lactose and? -lactose refers to the anomeric form of the glucopyranose ring only.
Lactose is hydrolysed to glucose and galactose, isomerized in an alkaline solution to lactulose, and is catalytically hydrogenated to a suitable polyhydric alcohol, lactitol. Lactulose is a commercial product, used for the treatment of constipation.
Maps Lactose
Isolation
Several million tons are produced annually as a by-product of the dairy industry. Whey consists of 6.5% solids of which 4.8% are lactose, which is purified by crystallization. Whey or plasma milk is the remaining liquid after the milk is dried and filtered, for example in cheese production. Lactose consists of about 2-8% by weight of milk. Industrially, lactose is produced from whey permeate - the filtered whey for all the major proteins. Protein fractions are used in infant nutrition and exercise nutrition while permeate can evaporate up to 60-65% solids and crystallize during cooling. Lactose can also be isolated by diluting whey with ethanol.
Metabolism
Baby mammals breastfeed their mothers to drink milk, which is rich in lactose. Intestinal villi secretes the enzyme lactase (? -D-galactosidase) to digest it. This enzyme cuts the lactose molecule into its two subunits, simple sugar glucose and galactose, which can be absorbed. Since lactose is predominantly in milk, in most mammals, lactase production gradually decreases with maturity due to a lack of sustained consumption.
Many people with ancestors in Europe, West Asia, South Asia, the Sahel belt in West Africa, East Africa and other parts of Central Africa maintain lactase production to adulthood. In many of these areas, milk from mammals such as cattle, goats, and sheep are used as food sources. Therefore, in these areas the gene for lactase production for the first lifetime evolved. Adult lactose tolerance genes have evolved independently in different ethnic groups. By decline, more than 70% of Western Europeans can drink milk as adults, compared with less than 30% of people from Africa, East and Southeast Asia, and Oceania. In people who are lactose intolerant, lactose does not decompose and provides food for intestinal flora that produces gas, which can cause diarrhea, bloating, flatulence, and other gastrointestinal symptoms.
Lactation
The synthesis of lactose is essentially one-way and can not cross the Golgi membrane. The resulting lactose accumulation is the main source of osmotic pressure, attracting most of the milk content.
Apps
Mild flavors and easy handling properties have led to their use as carriers and stabilizers of aromas and pharmaceutical products. Lactose is not added directly to many foods, because its solubility is less than other sugars commonly used in foods. Infant formula milk is an exception, in which the addition of lactose is necessary to match the composition of human milk.
Lactose is not fermented by most yeast during brewing, which can be used for profit. For example, lactose can be used to sweeten beer plump; The resulting beer is usually called milk or creamy stout cream.
The yeast belonging to the genus Kluyveromyces has a unique industrial application because they are able to ferment lactose for ethanol production. The lactose excess of the whey by-product of dairy operations is a potential source of alternative energy.
Another significant use of lactose is in the pharmaceutical industry. Lactose is added to tablets and capsule drug products as ingredients due to their physical properties and functions, ie , compressibility and cost effective use. For the same reason can be used to cut (dilute) illegal drugs.
History
The first lactose raw isolation, by Italian physician Fabrizio Bartoletti (1576-1630), was published in 1633. In 1700, Venovius pharmacist Lodovico Testi (1640-1707) published a testimonial booklet for the strength of milk sugar ( saccharum lactis ) to relieve, among other diseases, the symptoms of arthritis. In 1715, the Testi procedure for making milk sugar was published by Antonio Vallisneri. Lactose was identified as sugar in 1780 by Carl Wilhelm Scheele.
In 1812, Heinrich Vogel (1778-1867) recognized that glucose is the product of lactose hydrolysis. In 1856, Louis Pasteur crystallized another component of lactose, galactose. In 1894, Emil Fischer had set the component sugar configuration.
Lactose was named by the French chemist Jean Baptiste AndrÃÆ' Â © Dumas (1800-1884) in 1843. In 1856, Louis Pasteur was named galactose "lactose". See:
- Pasteur (1856) "Note sur le sucre de lait" (Note about milk sugar), Comptes rendus , 42 Ã:: 347-351. From page 348: "Je proposed de le nommer lactose ." (I propose to name it lactose .)
In 1860, Berthelot named it "galactose", and transferred the name "lactose" to what is now called lactose. See:
- Marcellin Berthelot, Chimie organique fondÃÆ'â € â € <Â © e sur la synthÃÆ'¨se [Organic Chemistry by synthesis] (Paris, France: Mallet-Bachelier, 1860) , vol. 2, pp. 248-249 and pp. 268-270. & Lt;/ref & gt; It has the formula C 12 H 22 O 11 and the hydrate formula C 12 H 22 O 11 Ã, Â · H 2 O, making it a isomer of sucrose.
See also
- Lactose intolerance
- Nectar
- Sugar in wine
- lac operon
References
Source of the article : Wikipedia
0 Comments