Rheological characteristics of native and steamed wheat flour suspensions

Impact of Particle Size on the Rheological Properties and Amylolysis Kinetics of Ungelatinized Cassava Flour Suspensions

The effect of particle size on enzymatic hydrolysis of cassava flour at subgelatinization temperature was investigated. A multiscale physical metrology was developed to study the evolution of different physical-biochemical parameters: rheology, granulometry, and biochemistry. In this study, four fractions of cassava flour based on the particle sizes under 75 µm (CR075), 75–125 µm (CR125), 125–250 µm (CR250), and 250–500 µm (CR500) were screened for enzymatic hydrolysis effect. The results showed that all cassava flour suspensions exhibited a shear-thinning behavior, and the viscosity increased drastically with the increase of particle size. During hydrolysis, the viscosity reduced slightly and the non-Newtonian behavior became negligible beyond 4 h of the process. The particles size for CR075 and CR125 increased steadily in diameter mean. The samples of CR250 and CR500 showed more fluctuation by first decreasing, followed by increasing in particle sizes during the process. The highest hydrolysis yield was found for samples with particle size under 125 µm (89.5–90.7%), suggesting that mechanical treatment of cassava can enhance the bioconversion rate.

Rheological Properties of Batters for Coating Products - Effect of Addition of Corn Flour and Salt

The contributions made by corn flour (0, 3 and 6%) and salt (0 and 5.5%) to the rheological properties of a commercial batter mix were studied. The properties of the wheat flour that are the base of the mix were studied first, then the corn flour, salt and other ingredients were added step by step. All the samples showed a shear-thinning behaviour. An increase in the consistency index was obtained when corn flour was present, while the presence of salt produced a remarkable decrease. No differences in viscoelastic behaviour were found when corn flour up to 6% was added, and the behaviour had a clear elastic component. The addition of salt produced a more viscous behaviour. An increase in the gelatinisation temperature of batters was observed in the formulations with salt.

Mathematical modelling of peristaltic propulsion of viscoplastic bio-fluids

This article studies theoretically the transportation of rheological viscoplastic fluids through physiological vessels by continuous muscle contraction and relaxation, that is, peristalsis. Both cases of planar and cylindrical physiological vessels are considered. A mathematical model is developed under long wavelength and low Reynolds number approximations. Expressions for axial velocity in core region, axial velocity in plug flow region, volume flow rate and pressure gradient in non-dimensional form are obtained. A comparative study of velocity profiles, pressure distribution, friction force and mechanical efficiency for different viscoplastic liquids is conducted. The influence of width of plug flow region, shear rate strain index and yield stress index on the pressure distribution, friction force and mechanical efficiency is elaborated. The study is relevant to gastric fluid mechanics and also non-Newtonian biomimetic pump hazardous waste systems exploiting peristaltic mechanisms.