The local and cooperative dynamics in atactic (a-PS) and syndiotactic (s-PS) polystyrene were studied by broadband dielectric spectroscopy. Besides the known alpha-relaxation, two additional relaxation processes beta(1) and beta(2) were revealed in various samples of a-PS and s-PS films cast from solvent solutions. These new dynamic processes show ...
In this paper we predict the water activity and initial freezing point of food products (meat and fish) based on their composition. The prediction is based on thermodynamics (the Clausius-Clapeyron equation, the Ross equation and an approximation of the Pitzer equation). Furthermore, we have taken the effect of bound water into account, by using a ...
Published in Journal of Thermal Analysis and Calorimetry
The interactions between Carbopol and β-cyclodextrin (BCD) or hydroxypropyl-β-cyclodextrin (HPBCD) were studied by differential scanning calorimetry (DSC) and FTIR spectroscopy. Aqueous solutions of both components were desiccated by freeze-drying or heating in an oven (films) at various temperatures. The use of different drying procedures allowed ...
Literature on the crispy / crunchy behaviour of cellular solid foods with a crust is discussed. The emphasis is on products with a dry crispy or crunchy crust as bread and various snacks and especially on mesoscopic and macroscopic aspects. Successively, the sensory sensation involved, the relation to fracture behaviour, morphological aspects, and ...
A method was developed to prepare films based on industrial wheat gluten, from aqueous dispersion at neutral pH. An essential step in this procedure is to prepare aqueous dispersions in such a way that coagulation of the vital wheat gluten is prevented. In contrast to current procedures, adjustment of the pH or addition of organic solvents can be a...
The interaction of crystalline amylose and of crystalline and amorphous amylopectin with the plasticisers glycerol or ethylene glycol in the absence of water was studied, by using differential scanning calorimetry (DSC) and solid state nuclear magnetic resonance (NMR) spectroscopy. Upon heating starch freshly mixed with plasticisers, a strong exoth...
In the complex dynamics of glass forming systems, and in particular of polymers, there exists a region in length scales which remains basically unexplored: that of the so-called intermediate length scales. These correspond to several times the inter-molecular distances. For polymer systems, the dynamics under question lays between the large scale R...
Ageing of gelatinised and partly gelatinised potato starch and wheat starch were investigated in the presence of plasticisers with increasing size and number of OH groups (ethylene glycol, glycerol, threitol, xylitol, glucose, and for potato starch also maltose). The influences of these plasticisers and of granular remnants (ghosts) on recrystallis...
Relaxation phenomena are controlled by thermally activated or by free-volume activated kinetics. Evaluation of the kinetic parameters across the whole experimental window is of prime importance. Techniques that provide information about the entire landscape of activation energies or fractional free volumes are discussed. Emphasis is given to a fine...
The interaction between amylopectin, a starch polysaccharide, and ethylene glycol (EG) was investigated using broad-band dielectric relaxation spectroscopy. Water-free amylopectin (AP) was mixed with 21 wt % ethylene glycol. This resulted in a continuous ethylene glycol phase, as well as a molecularly mixed AP/EG fraction. After storage at room tem...
