Saccharose hydrolysis

The study of the hydrogenolysis of saccharose to 1,2-propane diol has shown that a better yield can be obtained by the separation of hydrolysis and hydrogenation steps, from the bond cleavage. This can be achieved by adjusting the pH during the reaction. The hydrogenolysis of different oses has shown a difference in the selectivity of the reaction. An adsorbed form of the polyols can account for these differences. Indeed some oses like mannose and galactose have no hindrance to form the proposed complex. 

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 ... 

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. 

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. 

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. 

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. 

Amyloid.—When treated with concentrated sulphuric acid cellulose dissolves and undergoes hydrolysis. If the solution is diluted with water a gelatinous product is obtained which gives the blue color with iodine characteristic of starch. This product is known as amyloid. When boiled in the dilute acid the amyloid is hydrolyzed and dextrin and finally glucose are obtained. Concentrated hydrofluoric acid and phosphoric acid also dissolve cellulose. With glacial acetic acid in the presence of acetic anhydride and sulphuric acid cellulose yields acetyl derivatives indicating its alcoholic character. From the products of this reaction the acetate of a di-saccharose is obtained. 

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. 

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. 

Which monosaccharides are produced by the hydrolysis of sucrose (saccharose) ... 

What is the mass percentage of a saccharose solution if 228 grams of it produces 72 grams of glucose after hydrolysis in acidic medium ... 

Enzymatic hydrolysis of polysaccharides (cellulose, starch) or oligosaccharides (maltose, saccharose, lactose) for the synthesis of food products is another class of processes MBR have been applied to. Paolucci-Jeanjean et al [4.56] have recently reported, for example, the production of low molecular weight hydrolysates from the reaction of cassava starch over a-amylase. In this case the UF membrane separates the enzyme and substrate from the reaction products for recycle. Good productivity without noticeable enzyme losses was obtained. Houng et al [4.57] had similar good success with maltose hydrolysis using the same type of MBR,... 

To illustrate these points further, let us examine the results from a biochemical experiment in which the rate of hydrolysis of sucrose by the enzyme saccharose is investigated. This enzyme, or biological catalyst (of which we shall speak in more detail later), catalyzes the reaction ... 

The data of Kuhn showed that the initial rate of hydrolysis of the substrate sucrose (—d[S]/df) was a function of the substrate concentration [S] when the saccharose enzyme concentration [E] was constant (Fig. 2-3). At low substrate concentrations the rate of hydrolysis appeared to be proportional to sucrose concentration, that is, -- d[SJ/df = k[S], while at higher sucrose concentrations the rate of hydrolysis approached a maximum rate that was apparently independent of sucrose concentration, that is, -d[S]/df = constant. 

Yeast uses fermentable sugars as nutrients. These sugars are the direct precursors of ethanol. Glucose and fructose are readily fermentable, while saccharose is fermentable after chemical or enzymic hydrolysis into glucose and fructose. Pentoses are not fermentable. 

Saccharose is fermented by yeast, after hydrolysis into glucose and fructose, under the influence of yeast invertase. Saccharose cannot, therefore, be present in wine, unless it has been added illegally after fermentation. Saccharose is the main sugar used to add potential alcohol to grapes (chaptal-ization), due to its purity and low cost (Volume 1, Section 11.5.2). 

The experimentally measured and the calculated decrease with time of the five fermentable sugars at 14° C in the pilot plant fermentor are represented in Figure 4. As expected, glucose, saccharose, fructose, maltose and maltotriose are removed at different rates from the medium. Glucose, which is partly produced by the saccharose hydrolysis, is taken up the fastest, the initial assimilation of maltose and maltotriose being repressed by the presence of glucose. 

Hydrolysis. Ex. the transformation of saccharose into glucose and levulose, or that of starch into glucose, both under the influence of dilute adds. 

Products of hydrolysis penetrate into cells of microorganisms and in them, with the participation of enzymes, are subjected to fermentation and anaerobic oxidation, converting into fat acids (R-COOH) with large number of carbon atoms (propionic, butanoic, etc.), alcohols, aldehydes and also COj, and NHj. An example is saccharose acidogenesis reactions... 

C, [ago -75°- -19 (H O) p-DL-xylo-pyranose, OL-form, mp. 129 -131 °C. The L-forms are not natural. An aqueous solution of X. at, e.g., 31 °C, contains 36.5% a-pyranose, 63% )S-pyranose, <1% a-and /3-furanose, and 0.02% aldehyde. X. is obtained technically from the saccharification of wood and from the residues of cellulose production or, respectively, by isolation from xylans or from ears of corn by hydrolysis with dilute acids. Reduction of X. furnishes xylitol which can be used as a sugar substitute. X. itself would also be suitable for use as a sweetener but has only half the sweetness of saccharose and also shows laxative effects. 

Zirconia, which is stable as well as titania, especially, in alkali solution, is also one of the promising materials for separation membranes. Several manufacturers have commercialized zirconia UF membranes, but not NF membranes. Zirconium propoxide [30] or butoxide [31], which are mainly used as precursors of zirconia sols, are highly sensitive to water to form suspensions (the reaction rate with water is much faster than titanium alkoxide), the preparation of nanosized sols is difficult. Therefore, very few reports have appeared on the successful preparation of zirconia nanofiltration membranes. Vacassy et al. [30] added acetylacetone to zirconia propoxide to prevent hydrolysis, and reported a successful preparation of porous zirconia membranes showing a water permeability of 3.4 X 10 ms Pa and a rejection of 55% towards saccharose (MW = 342). 

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