Observation of wheat flour doughs under mechanical treatment using confocal microscopy and classification of their microstructures

Abstract

RheOptiCAD Ò is a cell allowing observation of microstructures under thermo-mechanical treatments. Using the device fitted on a confocal microscope, wheat flour doughs containing 3 levels of water were studied. Dough were placed between 2 parallel plates and submitted to motion of the bottom one. Temperature was controlled and fixed at 20 C. Methodology and experimental parameters, but also balance between optical and mechanical ones are described and justified to set a dynamic observation in real time. Rhodamine B labeled gluten network was observed under dynamic mechanical treatment, i.e. a 0.4 mm-0.3 Hz oscillation applied during 30 s. The evolution of the gluten network microstructure along time of deformation and depending on the recipe was studied. Image sequences are presented to visualize the qualitative differences in the network. Differences in microstructures were observed. A grey scale mathematical morphology is proposed to qualify and quantify these differences. Images can be separated according to the level of orientation of the network and to the local protein concentration in the gluten fibers.

Stabilizing highly hydrated wheat flour doughs by adding water in two steps

“…shows large green interconnected strands corresponding to a gluten network as observed by Boitte et al (2013). In the case of dough with 50 wt% of water content, three minutes of mixing is sufficient to enable the formation of a rather well developed protein network.…”

“…In the case of dough with 50 wt% of water content, three minutes of mixing is sufficient to enable the formation of a rather well developed protein network. The strands are oriented in the same oblique direction, probably due to slight shearing when the dough was placed between the two microscope slides (Boitte et al, 2013). The small pale green spots on the strands may be starch particles embedded in the gluten strands.…”

Latest advances in imaging techniques for characterizing soft, multiphasic food materials

“…By these means, the microstructure of foods can be directly related to macroscopic properties, such as shear and bulk moduli. A custom-made confocal rheometer was described by Dutta et al (2013), and the same authors employed it in the study of wheat dough (Boitte et al, 2013). Recent work from Tran-Ba et al (2017) involved the study of collagen network gelation, where additional parameters were obtained from image analysis of the confocal images, such as fractal dimension and gelation time.…”

Natural rubber‐carbon black coagulation: Following the nanostructure evolution from a colloidal suspension to a composite

“…The perfect planarity and parallelism of these two microscopy coverslips were suitable for the application of controlled shear. This was obtained using a commercial device called RheOptiCAD 15,16 (CAD instrument). It provided the ability (a) to move the top plate down at a constant and low speed to prevent excessive compression of the sample until a gap width of 500 μm was reached between the plates and (b) to connect each plate to a motor controlled by software that allowed straight translation.…”