Carbohydrate Test

1. Molish test

In a carbohydrate known some testing to determine the content contained in these carbohydrates. One of the tests conducted to determine the presence or absence of carbohydrates is the Molisch test. When there are several solutions that are not known for certain that the solution contains carbohydrates or not, this test can be performed to determine the carbohydrate content.

Solution of a positive reaction will give a purple ring when direksikan with Naphthols and concentrated sulfuric acid. It is estimated, the concentration of concentrated sulfuric acid acts as an agent acting on sugar dehydration to form furfural and its derivatives are then combined with Naphthols to form a colored product.

2. Iodine test

Test or tests are used to separate the starch contained in the solution. Positive reaction is characterized by a change in color to blue. The resulting blue color is thought to result from the complex bond between starch with iodine. When starch that has been poured iodine and then heated, the color produced as a result of a positive reaction will disappear.

And when cooled will re-appear in blue. In the starch itself consists of two kinds of starch that is amylose is not soluble in cold water and amylopectin is soluble in cold water. When starch dissolved in water, amylose will form micelles which molecules are clustered and are not visible because it is only at the molecular level.

These micelles can bind I2 contained in the reagent iodine and gives a distinctive blue color of the solution being tested. At the time of heating, the molecules repel each other so that micellespun will no longer be formed so that no longer bind to I2. As a result the typical blue color is caused to disappear.

Micelles will be formed again when cooled and re-emerged khaspun blue. Characteristic blue color caused as a result of positive reaction, will also be lost if the solution that has been positive in testing with iodine added NaOH. Na + ions that is alkaline will bind iodine so that the typical blue color will fade and disappear.

3. Experiment Benedict

Benedict test aims to determine the reducing sugar in a solution with the indicator changes color to red brick in particular. Benedict's reagent is used to test or examine the presence of reducing sugars in a liquid.

Monosaccharides that are redutor, with diteteskannya reagent will cause the brick red precipitate. In addition to testing the existence of reducing sugars, is also true in quantitative, as more and more sugar in solution, then the darker color of the sediment.

4. Fermentation experiments

Percobaaan fermentation conducted to determine the sugar that can be fermented. In this experiment, after a carbohydrate solution added to the suspension of yeast and aged for 1 hour in vitro fermentation, CO2 bubbles appear in the solution. In addition to CO2 bubbles appear, the solution can be kissed by the smell of alcohol. This situation indicates that the carbohydrate groups that can contain sugars that can be fermented.

5. Test Seliwanoff

Some carbs have a ketone group, a ketone group can be determined through testing seliwanoff. If the carbohydrate-containing ketone group is reacted with seliwanoff will show a red color as a positive reaction.

The presence of red color is the result of condensation of resorcinol which is preceded by the formation of hydroxy methyl furfural. The process of formation of hydroxy methyl furfural comes from the conversion of fructose by acid hot klorik who then produce acids and hydroxy methyl furfural livulenik.

CARBOHYDRATE

CARBOHYDRATE

• Definition

Carbohydrates are organic compounds consisting of carbon, hydrogen, and oxygen. For example; C6H12O6 glucose, sucrose C12H22O11, cellulose (C6H10O5) n. The general formula of carbohydrates Cn (H2O) m. Because such a composition, this compound was suspected as carbon hydrates, but since 1880, the compound is not a hydrate of carbon. Another name from carbohydrates is saccharide, derived from the Arabic "sakkar" means sugar. Simple carbohydrates have a sweet taste that is associated with sugar. Seeing the molecular structure, carbohydrate rather defined as a polihidroksialdehid or polihidroksiketon. Examples of glucose, is a polyol aldehyde because it has an aldehyde group da 5 hydroxyl group (OH).

(http://qforq.multiply.com/journal/item/2)

• Classification of carbohydrates

1.      Monosaccharide
Monosaccharides are the simplest carbohydrates because the molecule consists of only a few atoms C and can not be described by way of hydrolysis of other carbohydrates. Monosaccharides can be divided into aldose and ketosa. Examples of aldose namely glucose and galactose. Example ketosa namely fructose.

2.      Disaccharides and oligosaccharides

Disaccharide is a carbohydrate composed of two monosaccharide molecules bonded through the-OH group with the release of water molecules. Examples of disaccharides are sucrose, lactose, and maltose.

3.      Polysaccharide
Polysaccharide is a carbohydrate formed from many saccharide as a monomer. The general formula polysaccharide that is C6 (H10O5) n. Examples of polysaccharides are cellulose, glycogen, and starch.

(http://id.wikipedia.org/wiki/Karbohidrat)

• FUNCTION

a)      The role of the biosphere

Photosynthesis provides the food for almost all life on earth, either directly or indirectly. Autotroph organisms like green plants, bacteria and photosynthetic algae use photosynthesis results directly. Meanwhile, nearly all heterotrophic organisms, including humans, is really dependent on the organism Autotroph to get food.
In the process of photosynthesis, carbon dioxide is converted into carbohydrates which can then be used to synthesize other organic material. Carbohydrates produced by photosynthesis is a three-carbon sugar called glyceraldehyde 3-fosfat.menurut rozison (2009) This compound is the basic ingredient of other compounds that are used directly by Autotroph organisms, such as glucose, cellulose, and starch.

b)      Role as fuel and nutrients

Potatoes are one of the foods that contain lots of carbohydrates.
Carbohydrates provide the necessary basic needs of the living body. Monosaccharides, particularly glucose, is the main nutrient cells. For example, in vertebrates, glucose in the bloodstream so that the flow is available to all body cells. The body's cells absorb glucose and retrieve stored energy in the molecule is in the process of cellular respiration to run the body's cells. In addition, carbon monosaccharide skeleton also serves as a raw material for the synthesis of other types of small organic molecules, including amino acids and fatty acids. As for human nutrition, 1 gram of carbohydrate has four calories of energy value. [5] In the diet of people of Southeast Asia including Indonesia, are generally quite high carbohydrate content, ie between 70-80%. Raw foods are sources of carbohydrates such as whole grains or cereals (wheat and rice), tubers (potato, cassava, sweet potato), and sugar. However, the digestibility of carbohydrates of the human body vary depending on the source, which varies between 90% -98%. Lower fiber digestibility of carbohydrates to 85%. [7] Humans can not digest cellulose so that the cellulose fibers are used for human consumption only pass through the digestive tract and out with feces. Cellulose fibers erode the wall of the digestive tract and stimulate mucus that helps food pass through the digestive tract smoothly so-called cellulose as an important part of a healthy diet. Examples of foods that are rich in cellulose fiber are fresh fruits, vegetables, and grains. Aside from being a source of energy, carbohydrates also serves to maintain acid-base balance in the body [citation needed], play an important role in metabolic processes in the body, and forming the structure of the cell by binding to proteins and fats.

c)      Role as energy reserves

Several types of polysaccharides function as material deposits or reserves, which will be hydrolyzed to provide sugar to the cells when needed. Starch is a storage polysaccharide in plants. Plants accumulate starch as granules or granules in the plastids organelles, including chloroplasts. With synthesize starch, plants can accumulate excess glucose. Glucose is the main fuel cell, so that the starch is a reserve of energy.
Meanwhile, keep animals polysaccharide called glycogen. Humans and other vertebrates store glycogen mainly in liver and muscle cells. The decomposition of glycogen in these cells will release glucose when it needs sugar to rise. However, glycogen can not be relied upon as an energy source of animals for a long time. Glycogen deposits will be exhausted in just over a day unless it is restored by eating food. 

d)     Role as a builder material

Organisms build strong materials of structural polysaccharides. For example, cellulose is the main component of plant cell walls. Cellulose is like fibers, clay, insoluble in water, and are found primarily in the stalks, stems, branches, and all woody parts of plant tissue. Wood is mainly made of cellulose and other polysaccharides, such as hemicellulose and pectin. Meanwhile, the cotton is made almost entirely of cellulose.
Another important structural polysaccharide chitin is, carbohydrates that make up the outer skeleton (exoskeleton), arthropods (insects, spiders, crustaceans, and other similar animals). Pure chitin-like skin, but will harden when coated with calcium carbonate. Chitin is also found in various types of fungal cell walls.
Meanwhile, the bacterial cell wall made of composite structures with carbohydrate polysaccharide peptide, called peptidoglycan. The walls of these cells form a rigid and porous skin cells that provide wrap the physical protection of the soft cell membrane and cytoplasm in the cell. Other structural carbohydrates which is also a combination of carbohydrate molecules with other molecules are proteoglycans, glycoprotein, and glycolipid. Proteoglycans and glycoproteins composed of carbohydrates and protein, but proteoglycans consist mainly of carbohydrates, whereas glycoprotein composed mainly of protein. Proteoglycans found for example in the intercellular adhesive on the tissue, cartilage, and synovial fluid that lubricate the joints muscles. Meanwhile, the glycoprotein and glycolipid (a combination of carbohydrates and lipids) found in many animal cell surface. Carbohydrates in general the form of oligosaccharides and glycoproteins can serve as a marker of cell. For example, the four human blood group ABO system (A, B, AB, and O) reflects the diversity of oligosaccharide on the surface of red blood cells.

(http://id.wikipedia.org/wiki/Karbohidrat)

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