HYDROTHERMAL MODIFICATION OF STARCHES - THE DIFFERENCE BETWEEN ANNEALING AND HEAT MOISTURE-TREATMENT

Annealing and heat/moisture-treatment both cause a physical modification of starches without any gelatinization, or any other damage of the starch granules with respect to size, shape or birefringence only via a controlled application of heat/moisture. Since with respect to the application properties (gelatinization, viscosity etc.) almost idential modifications can be obtained with both treatments, there was no exact differentiation between the two treatments types. By application of both treatments as well as a combination of both to potato starch it could be demonstrated that both treatments cause completely different alterations of the internal granule structure. From the interpretation of the Brabender viscosity, the sorption isotherm, the DSC-curves and the X-ray diagrams it could be confirmed that a heat/moisture-treatment always means a structure alteration from a B-type in the direction of an A-type structure, whereas within annealing processes the property alteration have to be explained by a modification of the binding forces between the crystallites and the amorphous matrix.