The rheological properties of Common Black Horehound, Globe Thistle, and Squill types of dark‐colored Jordanian honey were examined. The types of honey used were identified via assessing the source of nectar using pollen analysis (Melissopalynology). The apparent viscosity, η, was measured as a function of the shear rate, γ. In addition, the apparent viscosity was measured, at constant shear rate (6.12 s−1), as a function of shearing time. Newton's law of viscosity (i.e., τ=ηγ) was found to adequately (R2∼ 0.99) describe the flow behavior of honey samples. The apparent viscosity was found to decrease with temperature, and the temperature dependence of viscosity was contrasted versus both Arrhenius model (η=ηoeEa/RT) and WLF model (η/ηG= 10 (C1(T–T)/C2+(T–TG))). Although Arrhenius kinetics may fit the viscosity versus temperature data for the examined types of honey, nevertheless, it gives a relatively high value of activation energy that is quite comparable with, if not even larger than, that of a typical chemical reaction. On the other hand, WLF‐model was found to adequately describe the data while at the same time it gives quite reasonable values of both TG and ηG, which are in agreement with those cited in literature.

This paper presents research on the effect of milk source on the rheological properties of curd during the gelation process of yogurt. The highest value for viscosity was exhibited by ovine milk, followed by caprine, bovine and camel milks. For bovine, ovine and caprine milk, three different transient viscosity stages were identified and described by mathematical expressions, whereas camel milk showed no significant variation in viscosity during gelation. The chemical composition of milk, namely total solids and protein content, has a major effect on the rheological properties of curd. A power law model allows the determination of the flow behaviour index and the consistency coefficient of curd made from different milk sources.

The rheological characterization of sewage sludge at different steps of wastewater treatment is important since it allows predicting and estimating sludge behavior when submitted to almost all treatment and disposal operations. Rotating biological contactor (RBC) is being widely used for wastewater treatment, which is a biological treatment process following primary treatment. The rheological characterization of RBC sludge at different solid contents (TSS = 32.2 g/L-50.2 g/L) and temperatures (5-40 C) was carried out using a rotational viscometer. The RBC sludge showed a shear-thinning behavior, where the apparent viscosity decreased rapidly with the shear rate reaching the limiting viscosity (  ) at the infinite shear rate. An exponential relationship described the evolution of the limiting viscosity with the sludge TSS content. In addition, a dramatic increase in the limiting viscosity beyond a TSS concentration of 42.4 g/L has been observed. On the other hand, Bingham model described well the non-Newtonian behavior of sludge suspensions. It was clear that the yield stress is more sensitive than the Bingham viscosity for the variation in temperature and solid content. However, the rheological results revealed that both the limiting and Bingham viscosities have the same behavior with the TSS content and with the temperature. accordingly. The obtained yield stress increased significantly from 59 mPa at TSS=32.2 g/L and T=45 o C to 5520 mPa at TSS=50.2 glL and T=5 o C. On the other hand, the Bingham viscosity exhibited less pronounced

The flow curves and time-dependent flow properties of tomato paste and tomato reconstituted solution (TRCS) were assessed in this study at different concentrations and temperatures. The tomato-reconstituted solution was prepared by dissolving the powders (produced by the spray drying technique) in certain amount of water to provide the concentration required. Bingham model was found to be the most appropriate to fit the flow curves of tomato paste. The yield stress, B , significantly increased with concentration and decreased with temperature in both the forward-(increasing shear rate) and backwardmeasurements (decreasing shear rate). The Bingham viscosity, B , was found to increase with concentration and decrease with temperature. As for the TRCS, the flow curves were also best fitted by the Bingham model with shear stress values significantly less than that of tomato paste at the same concentration and shear rate. Tomato paste solutions showed a time-dependent rheological behavior while the TRCS showed a time-independent behavior. Tomato paste exhibited a thixotropic behavior at low shear rates and converted to an anti-thixotropic behavior at high shear rates.

In this paper, the rheological behavior of concentrated yogurt (Labneh) is presented. The rheological behavior of Labneh was measured using a rotational viscometer in a temperature range of 5-55°C. The tested Labneh exhibited shear-thinning and thixotropic behaviors. The power law model expressed as τ = mγ n was found to be the most appropriate for the rheological model of Labneh. The effects of temperature on power law parameters were determined. The parameter (m) significantly decreased with increasing temperature, while the parameter (n) slightly increased with temperature. It was also found that the Weltmann's model described well the relationship between the apparent viscosity of Labneh and the shearing time. The activation energy of flow was nearly constant for all samples tested and not affected by the shear rate.