The influence of high pressure on gel forming maltodextrins. Part 1: Macro-structure, thermodynamic and fluiddynamic effects. Part 2: Investigation of the primary structure, discussion and conclusions

English. The influence of static high pressure (600 MPa) on physical and chemical properties of maltodextrin powders, which have had low degrees of hydrolysis (DE 2-8 %) and water contents of 5-24 % w/w, and maltodextrin gels (15 % w/w) have been investigated. No cleavage of covalent bonds has been proved. High pressure treatment results in structural changes depending on water content, ageing and specification of the material. Structural changes concern the physical micro- and macro-structure. In comparison with the untreated material, a more compact maltodextrin powder with an increased solid density has been produced. The physico-chemical properties have changed after high pressure treatment. We found a series of weak glass transitions with pressure-treated as well as non-treated maltodextrin powders, which appear as series of local extreme values in the first derivative of DSC thermograms. Maltodextrin powders, which have aged after high pressure treatment, show increased peak temperatures and extrapolated onset temperatures of the 50 - 70 degrees C endothermic event and increased glass transition temperatures in DSC above a water content of 12 % (w/w). Glass transition temperatures between 22 degrees C and 155 degrees C have been determined within the investigated moisture range of 24 - 5 % (w/w). Maltodextrin gels are more homogeneous after high pressure treatment and keep a stable consistency, also after ageing (48 h), whereas the untreated sample separates out. It has been shown, that pressure-treated maltodextrin gels have a higher mechanical and thermal stability. Presumably, the use of pressure results in a deformation of the network of the concentrated solution and primary gel respectively, but chances for restructuring arise from this deformation.

German. Im Teil 1 wird uber deutliche Veranderungen der phanomenologischen, thermischen und mechanischen Eigenschaften infolge einer Hochdruckbehandlung berichtet. Im Teil 2 werden Untersuchungsergebnisse zur Veranderung der Primarstruktur, insbesondere der kovalenten Bindungen, durch Hochdruckeinfluss vorgestellt. Der 2. Teil umfasst ausserdem die zusammengefasste Ergebnisdiskussion sowie Schlussfolgerungen.