Dextrins preparation

Microscopic Examination.—Dextrin prepared by heating retains the structure of the original starch to a suffident extent to permit of its origin being determined by microscopic examination in oil or glycerine (not in water) see Fig. 37 of Hate V at end of chapter. 

Marked quantities of torrefied gluten are found in dextrins prepared by the action of heat on inferior wheat starch. In some cases the gluten occurs as small, hard lumps. 

Dextrine — preparation, properties, uses, and relation to starch and dextrose. 

Time, min. Maltose Starch Limit dextrin preparation ... 

Early reports of the partial hydrolj-sis of the Schardinger dextrins by paii-creatio amylase indicated that a-tetraamylose is more susceptible than /3-hexa-aniylose. This is most likely a reflection of the relative degree of purity of the/3-dex-trins the crude a-dextrin preparations probably contained starchy impurities which were attacked by the enzyme used. 

Judging from reports in the literature and the author s experience, one would think the preparation of the Schardinger dextrin acetates would be nearly fool-proof. Even so, widely varying optical rotations and other properties have been reported for these compounds. As has been seen, the variation in optical rotations, melting points, and freezing-point depression with different dextrin preparations has led to an abundance of confusion in this area. 

About fifteen years later. Greenwood classified only three groups of dextrins A) white dextrins prepared finrm starch in the presence of an acid... 

Phosphorus in starch is found in different forms, mainly starch phosphate monoester, phospholipids, and inorganic phosphate. 31P NMR spectroscopy was used to identify each of these forms in alpha-dextrins prepared from starches of different sources.128 Quantitative analysis was possible in DMSO solution. 

That this interpretation of the action of phosphorylase and the debranching enzyme is incorrect came later from the work of Walker and Whelan. They examined the structure of the limit dextrin prepared by the action of highly purified, muscle phosphorylase on amylopectin. Debranching of this dextrin by R-enzyme resulted in production of malto-tetraose. (Similar results were later obtained when glycogen -dextrin was debranched with pullulanase. ) It was therefore concluded that the unequal attenuation of the two chains by phosphorylase, proposed... 

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