Hydration, of starch

Hyaluronidase, effect on blood group substances, IV, 55 Hydration, of starch, I, 275 Hydratopectin, II, 239 Hydrazine, derivatives, in identification of uronic acids, I, 339 Hydrazine, l,2-bis(a-metbylbenzyl-)-,... 

In order for starch molecules to become detached from one another, they must be hydrated, a process accomplished in water slurry by using either thermal or chemical energy. Only then will the molecules be separated and uncoiled enough to be able to latch onto other separate particles and act as an adhesive. The most common form of chemical hydration of starch is through the use of aqueous alkali. Sodium hydroxide is capable of hydrating starch molecules without heat, but a specific minimum concentration must be reached for that to occur (2). 

The hydration of starch evokes thermal effects which are obviously also dependent on the starch variety. This is true because the external temperature does not affect426 the macrostructure and microstructure of starch below 140°C. An estimation of the heat of sorption is useful in determining the concentration of bound water.426-434 The heat of adsorption ranges from 0.255 to 0.100 kJ/mol and depends not only on the variety of starch, but also on the mode of drying of starch prior to measurement (Table XVIII).426... 

In general, anionic surfactants (monoglycerides and alkyl and aryl sulfates) restrict the hydration of starch and swelling. In contrast, cationic... 

Model studies by Strandine et al.869 documented that monoglycerides inhibit swelling and hydration of starch granules and flour when heated in diluted aqueous slurries. The soluble starch is retained within the starch... 

To study the effects of interaction of starch with silica, the broadband DRS method was applied to the starch/modified silica system at different hydration degrees. Several relaxations are observed for this system, and their temperature and frequency (i.e., relaxation time) depend on hydration of starch/silica (Figures 5.6 and 5.7). The relaxation at very low frequencies (/< 1 Hz) can be assigned to the Maxwell-Wagner-Sillars (MWS) mechanism associated with interfacial polarization and space charge polarization (which leads to diminution of 1 in Havriliak-Negami equation) or the 5 relaxation, which can be faster because of the water effect (Figures 5.8 and 5.9). 

Hydrazine hydrate may be titrated with standard acid using methyl orange as indicator or, alternatively, against standard iodine solution with starch as indicator. In the latter case about 0-1 g., accurately weighed, of the hydrazine hydrate solution is diluted with about 100 ml. of water, 2-3 drops of starch indicator added, and immediately before titration 6 g. of sodium bicarbonate are introduced. Rapid titration with iodine gives a satisfactory end point. 

Carbohydrates were first analyzed in the early nineteenth century and described as compounds that were literally hydrates of carbon because they had the general formula CX(H20)X. In recent years, carbohydrate molecules are generally classified on the basis of their structures, not their formulas. Among the compounds that belong to this family are cellulose, starch, glycogen, and most sugars. 

French500 has collected together unit-cell data for maltose hydrate and some poly-O-acylsaccharides in the hope that some packing information might be obtained which could be applied to the problem of starch structure. 

Starch annealing involves heating starches with sufficient hydration below their Tq to facilitate molecular mobility (Tester et ah, 2001). Annealing is defined as "a physical treatment that involves incubation of starch granules in excess (>60% w/w) or at intermediate (40-55% w/w) water content during a certain period of time at a temperature above the glass... 

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