Abstract
High-sensitivity temperature-controlled DSC measurements at a low heating rate and creation of differential DSC traces with respect to the reference material (completely dried starch) permitted to revise precisely the actual knowledge on the phase transformations in starch. Five types of well-reproducible transformations have been observed: (1) sharp endothermic transition occurring over the temperature range 319−333 K independent of the water content associated with melting of the crystalline part of the starch granule followed by a helix−coil transformation in amylopectin; (2) water content dependent slow exothermic transition associated with reassociation of the unwound helixes of amylopectin with parts of amylopectin molecules other than their original helix duplex partner, forming physical junctions and creating more general amorphous hydrogen-bonded associations; (3) water content dependent low-temperature exothermic transition associated with recrystallization of partly dehydrated starch; (4) high...
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