Starch (S6N10O5) n - polysaccharide which is composed of two fractions: 25% linear amylose and 75% amylopectin branched.It is formed on the light in plants during photosynthesis.
This material is a white powder which is insoluble in cold water to form a slurry.After settling on the bottom of the slurry tank postponed white precipitate, and the water can be drained easily.After drying the starch recovers all its properties.
in hot water as this material forms a colloidal solution - it is such a viscous liquid, which is also called starch paste and is often used in the home as an adhesive substance.And yet at this property based his cooking jelly and some desserts.
Starch - a chemically inert substance.In order for it to undergo a reaction must be involved in this process catalysts.
on its physical and chemical properties of the substance based application.Thus, starch and its derivatives are often used in the food, textile and paper industries.And for living organisms, he plays an important role.
To use this organic matter in industrial applications subjected to chemical vozdeystiviyu.Starch hydrolysis - the process of ion exchange between water and the substance, which can be enzymatic or acidic.
Chemical starch hydrolysis - reaction catalyst, as occurs with heating in the presence of inorganic acids.During this chemical reaction produces glucose, which can be expressed by the equation:
(S6N10O5) n + nH2O + (cat. H2SO4 + t °) = nC6H12O6.
But lately gaining popularity enzymatic hydrolysis of starch.Using special technology, it is obtained from ethyl alcohol, molasses and glucose, as well as by chemical hydrolysis.
advantage of this process is that it as a raw material charge starchy plant, e.g., corn, potato, maize, rice and others.These these sources, moreover, contain in their composition amylolytic enzymes, which are used in the hydrolysis process.
For example, such enzymes are isoamylase and pullulanase, glyukolinazy.Enzymes - natural catalysts that accelerate chemical reactions.Schematically, the process of starch degradation by enzymes as follows: → starch soluble starch (amylose) → oligosaccharides (dextrins) → disaccharide (maltose = malt) → α-glucose.It can also be expressed by the equation:
(C6H10O5) n + nH2O + (kat.- enzyme) = nC6H12O6
Visually you can see that there was a chemical hydrolysis, an experiment.Boil the mixture of starch paste with sulfuric acid.Check whether there has been hydrolysis - drip iodine.If the reaction is negative, then there is no blue or violet color, it means that the hydrolysis occurred.
now prove that the hydrolysis product - glucose.Was added to the alkaline solution and copper sulfate (II) (CuSO4).The precipitate copper hydroxide does not drop, the solution had turned a bright blue color.Heated and see precipitation terracotta (brick) color - it means that the glucose in the solution, which was formed during the hydrolysis.
In humans also occurs enzymatic hydrolysis of starch.This process is very important as this form carbohydrates, particularly glucose.It oxidizes in every cell to form water and carbon dioxide, thus releasing energy needed for normal functioning of the body.
Hydrolysis of starch with enzymes starts at the mouth when chewing.Human saliva contains an enzyme - amylase, which under the action of the starch is split into simpler components - dextrins.This process is a person can even feel it.After all, if a long time to chew the bread, then in the mouth appears sweet taste, which suggests that a process of hydrolysis of starch.Excess glucose, which is formed during the hydrolysis, is deposited in the liver as a reserve nutrient - glycogen.
