Fractionation by Leaching Techniques

Although most publications on starch in the past fifteen years have treated the properties of starch fractions, and not the fractionation of starch proper, a few deal with refinements of older fractionating techniques which are worth mentioning here. 

This last method was repeated in the author s laboratory, using 1 % sodium chloride solution (as the extractant) and potato starch from new Malta potatoes. Instead of hydrogen, use was made of oxygen-free nitrogen 

Chloral hydrate displays several properties which make it an extremely useful tool in starch research. As these features were recognized as long ago as 1902 by Mauch and, seemingly, have been lost sight of in the intervening years, it may be of interest to mention some of the more important results of his work. 

In his study of the properties of aqueous solutions of chloral hydrate as solvents for starch, Mauch describes the following results, (i) Starch dissolves in aqueous solutions of chloral hydrate containing at least 50 % by wt. of chloral hydrate, (ii) No dextrins can be found in these solutions and, hence, no degradation of the starch occurs, (m) Starch consists of at least two components (which he called amylogeen and amylodextrine ) and these components are present as separate entities in chloral hydrate solutions of starch, (iv) After dilution of the solutions with water, a precipitate is formed consisting of flat spherocrystals of the amylodextrine fraction. 

Unaware of these old findings, the present writer rediscovered the formation of complexes of chloral hydrate with amylose, and established its optimal conditions (Table II gives the critical region of concentration of chloral hydrate). Then, knowing the properties of chloral hydrate as a good solvent for starch, the development of a laboratory fractionation process became obvious. As, to date, no information regarding this work has been published, the details will be given here. 

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