DSC‐Untersuchungen an Stärke Teil I. Möglichkeiten thermoanalytischer Methoden zur Stärkecharakterisierung

Abstract

Die Differential Scanning Calorimetry (DSC) wurde angewendet zur Charakterisierung der Vorgange bei der Verkleisterung von Starken und der Reorganisation von Starkepolymeren (Retrogradation). Besonderer Wert wurde dabei auf die Optimierung des Menverfahrens gelegt. Aufgrund einer spez. Detektoranordnung des verwendeten Kalorimeters wird eine hohe kalorische Empfindlichkeit, bezogen auf das Probenvolumen, erzielt. Dadurch konnten neben den bekannten endothermen Umwandlungsenthalpien bei der Verkleisterung einiger Starken weitere Peaks aufgelost werden, die der Desintegration des Amylose-Lipid-Komplexes zugeschrieben werden. In Mischungen aus Amylose und Amylopektin werden unter bestimmten Umstanden deren Retrogradationsprodukte als diskrete Peaks beobachtet , die sich in ihrer Umwandlungstemperatur deutlich unterscheiden. Zum Schluf3 wird auf die Verkleisterung bei limitierten Wassergehalten eingegangen. Die Untersuchungen bestatigen kiirzlich veroffentlichte Ergebnisse. Die Differential Scanning Calorimetry ist damit zu einer nutzlichen analytischen Methode gereift, mit der Fragen der Starkechemie beantwortet werden konnen.DSC Investigations of Starches. Part 1. Feasibility of Thermoanalytical Methods to Characterize Starches. In this paper results on the application of Differential Scanning Calorimetry upon the gelatinization and reorganization of starch polymers (retrogradation) are discussed. Considerable emphasis was layed on optimization of the analytical method. A high caloric sensitivity related to the sample volume was accomplished based on a specific detector system of the used calorimeter. Due to these optimized conditionsbesides known endothermal enthalpy changes during gelatinizationfor some starches additional peaks could be detected that are attributed to the desintegration of the amylose-lipid-complex. Usingmixtures of amylose and amylopectin, discrete peaks from their retrogradation products are observed under certain circumstances. These differ clearly by transition temperature. Finally, gelatinization effects are discussed using limited water supply. Recently published results could be confirmed. Differential Scanning Calorimetry has been fully developed to an useful analytical method to answer questions within starch chemistry.

Staling of Bread: Role of Amylose and Amylopectin and Influence of Starch‐Degrading Enzymes

“…The firmness of both the control and the bread containing the maltogenic a-amylase was reduced to the level that was found for the bread with enzyme directly after baking. The fact that bread without enzyme cannot be refreshed to its original firmness is most probably due to aggregated amylose, which cannot melt at <150°C (Eberstein et al 1980). Only recrystallized amylopectin could be melted during the reheating step, which was confirmed by DSC measurements (Table I).…”

Effect of thermal history on amylose gelation

“…In contrast, amylose would take a much longer time to phase separate from a solution where most nuclei were previously molten by heating at higher T d. Crystal growth would occur in rare, well-separated areas of the solution, therefore resulting in separated crystals of a larger size and higher perfection. This model for amylose gelation is consistent with DSC measurements performed on recrystallized amylose [14]. The authors reported a major endotherm at temperatures between 150°C and 145°C, with a maximum at 137°C.…”

Structural investigation of amylose complexes with small ligands: inter- or intra-helical associations?

“…Nevertheless, for some types of complex whose crystallographic structure has been completely resolved, the ligand can be included within helices [1,2]. The structure of amylose complexes formed with a wide range of small molecules has been investigated mainly by X-ray and electron diffractions [2][3][4][5][6][7], differential scanning calorimetry (DSC) [8][9][10][11] and solid-state nuclear magnetic resonance (NMR) [12][13][14][15][16]. The best-known and described complex is the V-6I amylose hydrate (V-h) which is obtained with linear alcohols [3,[17][18][19][20] and monoacyl lipids [8,9,21,22].…”