Mono saccharoses

The termination ose, is given to all carbohydrate classes and to those individuals which have sugar character, e.g.j mono saccharoses glycerose, glucose, etc. 

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. 

Di-saccharoses or Hexo-bioses.—(i) The first group is known as di-saccharoses. These are so called because they split, on hydrolysis, into two molecules of hexose mono-saccharoses. The general formula for these di-saccharoses is C H2 20n-i, and the known members all have the composition formula C12H22O11. They are represented by such common substances as cane sugar, milk sugar and malt sugar. The reaction of hydrolysis is,... 

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 ... 

These hydrolyze to two molecules of mono-saccharoses, C6Hi206. 

Synthesis from Poly-alcohols.—We come, now, to that group of mono-saccharoses, the hexose mono-saccharoses, which contains the most important simple sugars which are known, viz., glucose and fructose. The hexoses may be prepared, synthetically, by oxidizing the hexa-hydroxy alcohols, e.g. mannitol, dulcitol, sorbitol, etc. (p. 219). 

From Formaldehyde.—Historically and physiologically, the most important synthesis of hexose mono-saccharoses is from formaldehyde. In 1861 Butlerow found that dioxymethylene (tri-oxymethylene), produced by polymerizing formaldehyde, yielded with hot lime water a sweet substance to which he gave the name of methylenitan. The substance reduced Fehling s solution, but was optically inactive and non-fermentable with yeast zymase. Later, Loew obtained a sweet, non-fermentable syrup by the direct action of lime-water on formaldehyde. This substance he called formose. He afterward obtained what he considered another sugar by the action of magnesium hydroxide upon formaldehyde. This substance was fermentable by yeast and to it he gave the name of methose. In 1887, Fischer and Tafel... 

It will be necessary, now, to consider the stereo-isomerism of those mono-saccharoses which contain more than three carbon atoms. The isomerism of the aldoses and ketoses is structural, depending upon the different groups present in the molecule. These two isomeric forms of the mono-saccharoses are found in the case of each member above the bi-ose group, as this can exist only in the condition of an aldehyde compound and not as a ketone. If we examine the structural formula of any mono-saccharose containing more than three carbons we shall find that they each contain at least one asymmetric carbon atom. In most cases two or more asymmetric carbons are present, as shown in the following formulas in which the asymmetric carbon atoms are marked. 

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. 

Invert Sugar. Inversion.—We have mentioned the fact that glucose may be obtained by the hydrolysis of cane-sugar. In this hydrolysis not only glucose but also fructose is obtained. Cane sugar is a di-saccharose of the composition C12H22O11. When it is hydrolyzed it splits and is converted into two molecules of mono-saccharoses. One of these molecules is glucose and the other is fructose. 

Alcoholic Fennentation.—The statements, just made, in regard to the alcoholic fermentation of the di-saccharoses, need to be explained. Yeast, i.e., ordinary beer yeast, contains several enzymes. The definite enzyme present in yeast, and which, alone, produces alcoholic fermentation of sugars, is the enzyme Z3rmase. This enzyme acts only upon the hexoses glucose, fructose, and galactose. It has no action upon either of the three di-saccharoses we have mentioned. When, however, cane sugar or malt sugar is treated with ordinary yeast alcoholic fermentation takes place. This is due to a preliminary action of other enzymes upon the di-saccharoses by means of which they are converted into mono-saccharoses and then the mono-saccharoses are fermented... 

Only one tri-saccharose is important. It is known as raffinose and has the composition Ci8H320]6. It is found in beets and is present in the molasses after the sucrose sugar is crystallized out. It is also found in barley and in cotton seeds. When this tri-saccharose hydrolyzes it yields first a di-saccharose known as melibiose and a monosaccharose fructose. The di-saccharose is then further hydrolyzed and yields two molecules of mono-saccharose, viz., glucose and galactose. The complete hydrolysis of the tri-saccharose, therefore, is as follows. 

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. 

Hexose Mono-saccharose Reduces Fehling s Solution... 

These hydrolyses indicate that starch is a compound existing as a complex molecule containing numerous mono-saccharose groups united in an anhydride constitution, similar to that shown to exist in the case of the di-saccharoses. The molecular mass of starch is unknown, but has been claimed to be that represented by the formula,... 

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. 

Constitution.—A study of the hydrolytic products obtained from cellulose indicates that it is a polysaccharose carbohydrate made up of hexose mono-saccharose units and in the hemi-celluloses and probably the ligno-celluloses the units may also be pentose mono-saccharoses. Normal cellulose is probably composed of glucose units only while the hemi-cellulose may contain mannose or galactose units. In regard to... 

Tannic Acids.—Closely related to gallic acid and to protocatechuic acid is a group of acids known as tannic acids. While the exact constitution of these is not known it is probable that they are anhydrides of different hydroxy benzoic acids, similar to the di-saccharoses as anhydrides of mono-saccharoses. This is indicated by the fact that on hydrolysis the tannic acids yield hydroxy benzoic acids. The different tannic acids are given names that indicate the hydrolytic products or the natural source. 

KETO HEXOSE. A si.x-carhon mono-saccharose which contains a carbonyl group, e.g, fructose. 

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