Water Sorption and Transport in Dry, Crispy Bread Crust

Water - sorption and dynamic properties of bread crust have been studied in gravimetric sorption experiments. Water uptake and loss were measured while relative humidity (RH) was stepwise increased or decreased (isotherm experiment) or varied between two adjusted values (oscillatory experiment). Experimental results were compared with the...

Relations between sensorial crispness and molecular mobility of model bread crust and its main components as measured by PTA, DSC and NMR

Consumer appreciation of brittle cellular foods, like bread crusts, depends on textural properties such as crispness. This crispy character is lost above a certain water activity. It is not known what exactly is happening in these crusts when water enters. So is it unclear whether it is the change in the starch or the gluten that initiates the...

Water uptake mechanism in crispy bread crust

Crispness is an important quality characteristic of dry solid food products such as crispy rolls. Its retention is directly related to the kinetics of water uptake by the crust. In this study, a method for the evaluation of the water sorption kinetics in bread crust is proposed. Two different sorption experiments were used: an oscillatory...

Water content or water activity: What rules crispy behavior in bread crust?

A dry crust loses its crispness when water migrates into the crust. It is not clear if it is the amount of water absorbed or the water activity (a w) that leads to a loss of crispness. The hysteresis effect observed when recording a water sorption isotherm allowed us to study the effects of aw and moisture content separately. All experiments...

Oscillatory water sorption test for determining water uptake behavior in bread crust

In this work, water sorption kinetics of bread crust are described using an oscillatory sorption test in combination with a Langmuir type equation. Both kinetic and thermodynamic information could be obtained at the same time. An advantage of applying a Langmuir type equation for a quantitative description of the water uptake kinetics is that no...

Visualisation of starch granule morphologies using confocal scanning laser microscopy (CSLM)

On the structure of K/l-hybrid carrageenans

The coil-to-helix transition and temperature dependence of the viscosity of commercial κ/ι-hybrid carrageenans produced by the red algae Sarcothalia crispata, Mazaella laminarioides, and Chondrus crispus were studied using rheometry and optical rotation. The structure of these κ/ι-hybrid carrageenans was determined by 1H and 13C NMR spectroscopy...

Confocal scanning light microscopy (CSLM) on mixtures of gelatine and polysaccharides

Demonstrations are given of the application of confocal scanning light microscopy (CSLM) on mixtures of gelatine with other food biopolymers. The various aspects of phase separation are visualised in two and three dimensional images. Contrast through fluorescence is obtained either by covalent labelling or non-covalent labelling. There is...