Dextrins reducibility changes

Thus, we see that Freudenberg passed through a change in views, from the notion that the Schardinger dextrins were chain molecules with a peculiar chain termination which rendered them non-reducing, to the current... 

Fig. 17.—Changes of Reducibility of Dextrins from Potato Starch Depending on Time of Roasting at 165° andpH 2.9. [Starchacidifiedwith(l)hydrochloricacid, (2) nitric acid, and (3) phosphoric acid. ]...

In the case of the White dextrins, pyrolysis induces an apparent hydrolytic reaction, because, with time, there is a steady increase in reducing power and cold-water solubility and a steady decrease in viscosity. These characteristic changes are shown in Fig. 1. Pastes made from such dextrins show gelation, or set-back, properties comparable to those of the original starch. 

The first investigation which used amylose as a model compound for dextrinization was that of Brimhall. She pyrolyzed amylose at 200°, and found that the changes observed in the reducing power, methylation end-group assay, /3-amylolysis limit, and solubility were all consistent with the concept that dextrinization causes the molecule to become branched. 

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