Properties and Structures of the Fractions

The solubility of the several starch components is determined not only by their respective structural configurations, but also by the associa- 

When an aqueous solution of the A-fraction is cooled in contact with butyl alcohol, it satisfies its associative tendencies through the formation of an alcoholate. Since butyl alcohol is probably adsorbed via its hydroxyl group, the alcoholate then presents a hydrophobic surface to the medium and precipitates from solution. The crystalline precipitate can be washed with cold water saturated with butyl alcohol, since this will not dissolve alcohol from the alcoholate and therefore does not disturb the crystal lattice. When the crystals are dried in the absence of water, the crystal structure is frozen without the establishment of intermolecular bonding. Consequently, the product can be dissolved in hot water. With cold water, the molecules immediately associate to give an insoluble gel. 

The B-fraction is conceived as a ramified molecule branched either in an orderly pattern or else in random maple tree fashion. In 

It is significant that no V diagram is obtained with ungelatinized granules or with retrograded starch. Hence Bundle presumes that the 

As further evidence of the linear character of the A-fraction, Whistler and Schieltz have shown that stretched films of its triacetate give typical fiber patterns on X-ray analysis. This is the first reported instance of oriented fiber structure from starch. 

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