Poly saccharoses

Mono-saccharoses.— The carbohydrates, or saccharoses, then, are divided into two large classes, viz., mono-saccharoses and poly-saccharoses,... 

Poly-saccharoses.—(II) Poly-saccharoses, as the name indicates, are not simple sugars, but are multiples of the unit sugars. On hydrolysis, they split into two or more molecules of one of the simple sugars, or mono-saccharoses. This class is further sub-divided into two subclasses due to the fact that some of them are compounds possessing true sugar characters, while others are not true sugars. 

Ila) Poly-saccharoses that are true sugars. The members of this sub-class consist of two groups, only one of which is of great importance. 

Tri-saccharoses or Hexo-trioses.—(2) The other less important group of the poly-saccharoses that are true sugars is that of the tri-saccharosesy or hexo-trioses. These split, as their name indicates, into three molecules of hexose mono-saccharoses. The formula corresponds to the composition C18H32O16. The hydrolysis may be represented by the reaction,... 

Poly-saccharoses not True Sugars.—(II ) The second-sub-class of poly-saccharoses consists of those carbohydrates which are not true sugars. This group is represented by such substances as starch, dextrin and cellulose. The group is usually known by the simple name, poly-saccharoses, as the specific names, di-saccharoses and trisaccharoses, are used for the members of the first subclass. We do not know how many molecules of mono-saccharoses are obtained from one molecule of these poly-saccharoses, because we do not know the molecular weight of the compounds. They are represented by the empirical formula (CfiHioOs), and their hydrolysis may be represented as follows ... 

Hydrolysis of Poly-saccharoses.— The most important relationship of the hexose sugars is that involved in the common method for their preparation. Poly-saccharoses, e.g.j cane sugar and starch, hydrolyze and split into two or more molecules of hexose sugars. On the hydrolysis of a di-saccharose two molecules of hexose sugars result. These two molecules may be the same hexose sugar or they may be different. When a true poly-saccharose, like starch, is hydrolyzed more than two molecules of hexose sugar result. These hydrolytic reactions will be considered in detail under the different poly-saccharoses. 

We may now take up the consideration of the individual carbohydrates following the order of our classification, viz., (i) Mono-saccharoses, (2) Di-saccharoses, or poly-saccharoses that are trtie sugars, and (3) Poly-saccharoses, or poly-saccharoses that are not true sugars. 

The group of di-saccharoses, or poly-saccharoses which are true sugars, includes three common and important members, (i) Cane sugar, or sucrose, perhaps the most important of all the carbohydrates, unless that position may be disputed by starch a poly-saccharose. (2) Malt sugar, or maltose, found in malt. (3) Milk sugar, or lactose, the sugar present in milk. 

The poly-saccharoses which are not true sugars, are usually called simply, poly-saccharoses. The most common and important ones are the following. 

General Character.—The poly-saccharoses are compounds made up of an unknown number of hexose mono-saccharose units. The com-... 

In the case of starch, dextrin and probably glycogen, the di-saccharose, maltose is an intermediate product of the hydrolysis. When hydrolyzed by enzymes two or more distinct enzymes are necessary to complete the hydrolysis of the poly-saccharoses to mono-saccharoses. With acids the hydrolysis goes through to the final product though the intermediate products are probably formed. 

Solubility.— The poly-saccharoses differ from the sugars in the absence of a sweet taste, in their non-crystalline character and in their general insolubility. Inulin and dextrin are soluble in water, glycogen is soluble to an opalescent liquid, while starch and cellulose are insoluble. In hot water starch forms a colloidal solution or emulsion, known as starch paste. Starch reacts with a solution of iodine and gives a beutifiul blue color. This is a characteristic reaction for starch and is used as a qualitative test, especially in microscopic examination. Dextrin exists in several forms, one of which known as erythro-dextrin, gives a red color with iodine. 

Iodine Reaction.—The other forms of dextrin known as achroo-dextrins, give no color with iodine. The following enzymes act upon the different poly-saccharoses hydrolyzing them as indicated ... 

We may now consider a few facts and additional properties of the individual poly-saccharoses. 

Hemi-Cellulose.—Hemi-cellulose is the name applied to a form of compound which is found in numerous seeds such as peas, beans, coffee, etc., and which differs in form from the fibrous variety. It is probably simpler or perhaps purer than normal cellulose and hydrolyzes more easily. On hydrolyzing celluloses of this type yield the hexose monosaccharoses, mannose and galactose and also pentose mono-saccharoses. They are therefore included in the group of poly-saccharoses termed mannans, galactans and pentosans (p. 380). The reserve food cellulose of germinating seeds belongs to this type. 

Inulin.— Inulin is found in certain plants, especially in the tubers of the Dahlia. It is isomeric with the other poly-saccharoses and is also a reserve food material. It is a white powder soluble in water. It is leva rotatory and gives no color with iodine. It is not hydrolyzed by diastase but by a particular enzyme known as inulase. Its peculiar characteristic is that by acid hydrolysis it yields only fructose. 

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