Rheological,thermal and structural behavior of poly(ε-caprolactone) and nanoclay blended films

Poly(ε-caprolactone)/nanoclay composite (PCLNC) films were prepared by solvent casting method using a wide range of layered silicate (2.5–10%) and were characterized by different techniques. Nanofiller dispersions in PCL matrix were studied by wide-angle X-ray diffraction (XRD) and transmission electron microscopy (TEM), and results indicated the formation of some intercalated nanostructure of PCLNC. Rheological and thermal properties of PCLNC were measured by parallel-plate oscillatory rheometry and differential scanning calorimetry (DSC), respectively. Rheological study indicated that the predominating liquid-like properties (viscous modulus, G″ > elastic modulus, G′) of neat PCL gradually transformed to solid-like (G′ > G″) behavior after incorporation of clay in the temperature range of 90–120 °C. A plot of G′ vs. G″ provide information on intercalation and microstructure of nanocomposite. Applicability of time–temperature superposition (TTS) principle and van Gurp–Palmen plot (phase angle vs. absolute complex modulus) on rheological data of clay incorporated PCL were employed and found that the results failed to follow the rules. Incorporation of the nanoclay into PCL matrix increased the crystallization temperature (T_c) and melting temperature (T_m) of neat PCL from 28.7 to 32.3 °C and 56.3 to 59.2 °C, respectively due to the nucleating effect, but the glass transition temperature (T_g) (≈−65 °C) was remained unaffected. The decrease in crystallinity with increase in clay concentration was confirmed by both XRD and DSC data.     

Rheological characterisation of cake batters generated by planetary mixing: Comparison between untreated and heat-treated wheat flours

The rheological behaviour of high ratio cake batters prepared with untreated and heat-treated wheat flours was analysed at different stages of the manufacturing process, namely slurry, (on aeration) foams and (with fat addition) aerated emulsions, featuring air volume fractions up to 0.50. Both steady shear and viscoelastic behaviours were studied. All materials exhibited shear-thinning behaviour at 20 °C over the shear rate range studied (0.07-10 s⁻¹). The generalised Cox-Merz rule could be applied to all samples. Materials prepared with heat-treated flours exhibited greater stability, as indicated by slurry thixotropy and cohesive energy, and the change in apparent viscosity and air content of foams and aerated emulsions on extended mixing. Foams and aerated emulsions showed significant elastic behaviour with G′∼G″. The temperature dependency of aerated emulsions was studied by oscillatory shear testing from 20 to 100 °C and indicated three regimes in temperature dependence: below 40 °C G′and G″ were insensitive to temperature; between 40 and 70 °C the complex viscosity exhibited Arrhenius-type behaviour, while above 70 °C G′ and G″ increased as expected for gelatinisation and foam setting. The weak gel model for foods was used to analyse the latter data sets and confirmed that the gel network generated in aerated emulsions prepared with heat-treated flours was significantly stronger than those made with unheated flours. The differences between flour types were also observed in tests on un- and heat-treated flours obtained from a second and third harvest. The impact of these quantifiable differences in rheology on performance during baking is discussed.     

Dynamic rheological and thermal characteristics of caramels

Small-amplitude dynamic viscoelastic properties of three different commercial caramel formulations were studied in the range of temperature and frequencies of 20-80 °C and 0.1-10 Hz, respectively, using a controlled rate rheometer. Dynamic shear results revealed viscous behaviour for caramel samples: magnitudes of viscous modulus (G″) were higher than those of elastic modulus (G′), and both increased with angular frequencies (ω). Temperature significantly (P<0.05) affected both G′ and G″; however, the change was insignificant at higher temperatures and frequency. Dynamic modulii-frequency data were adequately fitted by a power law-type relationship and regression parameters did not vary with temperature. Differential scanning calorimetry (DSC) was employed to examine the thermal transition of caramels. A shift in glass transition temperature (T_g) was noticed during thermal scanning (cooling and warming) of caramel samples. Melting and crystallization temperatures were varied among the caramels. Testing temperature and variation in compositions resulted in differences in rheological parameters, melting and crystallization temperatures of caramels.     

Influence of the particle size on the rheological behaviour of chestnut flour doughs

The rheological properties of chestnut flour (CF) doughs with different particle size were studied using a controlled stress rheometer. The mixing curves and heating–cooling cycle responses were previously obtained from the Mixolab® apparatus. Shear measurements (0.1–10 s⁻¹), oscillation measurements (1–100 rad s⁻¹ at 0.1% strain), temperature sweep (30–100 °C) to achieve the gelatinization temperatures and creep-recovery tests (loading of 50 Pa for 60 s) were conducted in the rheometer. Mixolab® showed that CF samples with smaller particle size needed more water absorption to reach a consistency of 1.1 Nm. Shear viscosities of CF doughs exhibited a Newtonian plateau at low shear rate and shear thinning behaviour at higher shear rate. Apparent viscosity increased with increasing average particle size and steady-flow curves were fitted using Cross model. Oscillatory measurements of CF dough showed that the storage modulus, G′, was greater than loss modulus, G″, for all samples in the tested angular frequency range. CF samples with smaller particle size presented lower G′ and G″ values. Creep-recovery tests of these flours showed that elasticity was limited and unrecoverable proportion was very high. Gelatinization temperatures measured using Mixolab® and rheometer were practically coincident.     

Impact of disperse microstructure on rheology and quality aspects of ice cream

Oscillatory thermo-rheometry (OTR) was used to correlate rheological properties with the microstructure and quality characteristics of ice cream. In a rotational rheometer (plate-plate geometry) the rheological behavior of ice cream was studied, performing oscillatory measurements at low deformation amplitudes for three different temperature ranges corresponding to important consumer properties of ice cream.The ice crystal microstructure determined the rigidity and “scoopability” of ice cream at low temperatures (−20°C to −10°C). The higher the overrun and the smaller the connectivity of ice crystals, the smaller were the measured storage and loss moduli G′ and G″.The slope of the variations in G′ and G″ with temperature in the range between −10°C and 0°C were correlated with the sensory impression of coldness. Decreasing overrun levels led to steeper slopes and correspondingly to a more pronounced impression of coldness.The microstructures of air and fat phases had also a significant impact on the rheology and the sensorial “creaminess” of ice cream especially in the molten state (0-10°C). With increasing overrun levels, ice cream showed increasing storage and loss moduli at temperatures higher than 0°C. Smaller air bubble sizes and increased fat globule aggregation in low temperature extruded (LTE) ice cream led to higher values of G″ in comparison to conventionally hardened (Freezer) ice cream.Sensorial studies demonstrated a close correlation between loss moduli G″ measured in the OTR-test and the ice cream quality parameters scoopability and creaminess. The improved scoopability and increased creaminess of LTE ice cream in comparison to Freezer ice cream was measured quantitatively by a decrease of G″ at a temperature of −15°C and a increase of G″ for ice cream in the molten state.     

Applicability of time-temperature superposition principle: Dynamic rheology of mung bean starch blended with sodium chloride and sucrose - Part 2

Dynamic rheological characteristics of mung bean starch individually and blending with sodium chloride (5-10%) and sucrose (5-10%) in aqueous medium were studied isothermally (70-95 °C). The elastic modulus (G′) of each dispersion was significantly higher than viscous modulus (G″) and showed a predominant solid-like property. Each ingredient affected the rheological behavior differently. Incorporation of sugar increased the gel rigidity, whereas sodium chloride-starch blend lowered the gel strength as function of concentration. The empirical principle of time-temperature superposition (TTS) was examined to bring experimental dynamic rheological data at various temperatures together into single master curves at a reference temperature of 80 °C. The complex viscosity (η^∗) master curve was obtained for the blends with slight deviation. The elastic modulus superposition (G′-ω) has been found to fail in the studied temperature regime. The failure of TTS was believed to be happened due to complex starch-additive-water matrix formation, temperature response of individual components and phase change during gelatinization of starch.     

Shear rate and cooling modeling for the study of candelilla wax organogels’ rheological properties

The rheological properties evolution, during the organogelation by cooling of candelilla wax (CW) solution in safflower oil, was studied using computational fluid dynamics (CFD). A simulated storage modulus (G′) model agreed satisfactorily with experimental observations. The gelation of 3% CW solutions was done using static conditions during the whole process (90–5 °C), or by applying a shear rate (180, 300 and 600 s⁻¹) during cooling from 90 °C to 52 °C and then continuing the cooling under static conditions up to the final temperature (i.e. 5 °C). The proposed model predicts G′ evolution as a function of temperature, and considers the final torque (Γ_f) of the sheared stage as an inductor of molecular flow alignment. Predictions revealed that the final solid-like component (i.e. G′) increases as the shear rate increases up to a maximum for a shear rate of about 400 s⁻¹. Then, final G′ value diminishes gradually, probably due to the destruction of microstructures that generate the gelation. The model was validated by graphical methods and variance measures. The results demonstrate the potential of CFD to allow the development of a model linking process variables (i.e. cooling and shearing) and rheological properties. This model can be successfully applied for process control purposes and for the design of organogels with predefined properties.     

Viscoelastic behaviour of heat-treated whey protein concentrate suspensions

The viscoelastic behaviour of heat-treated whey protein concentrate (WPC) suspensions was studied. Suspensions with total protein (TP) content of 5% and 9% w/v prepared from a commercial WPC with 38% w/w protein were treated at two temperatures (72.5 and 77.5 °C) during selected times to obtain 60% of denatured protein content. Unheated WPC suspensions were used as control. Frequency sweeps were performed in the range of 0.01–10 Hz at 20 °C. Mechanical spectra of WPC suspensions were similar to viscoelastic fluids. However, unheated WPC suspensions showed some mechanical characteristics of colloidal crystals, like little dependency of elastic (G′) and viscous (G″) moduli with TP content, solid-like mechanical spectra, and difficulty to flow at low content of TP. At a selected frequency of 1 Hz, viscous modulus was more frequency (ω) dependant on experimental conditions (TP and temperature) than elastic modulus. Mechanical spectra were modelled using power law equations (G′ = aω^x, G″ = bω^y), but only parameters of heat-treated WPC suspensions containing 9% of TP showed temperature dependency. Characteristic relaxation times (τ_c) were calculated as the inverse of the crossover frequency, where G″ = G′. Heat treatments produced a decrease in the extent of the elastic behaviour because heat-treated WPC suspensions presented higher phase angle and smaller τ_c values than unheated WPC suspensions for the same TP content. The τ_c decreased when treatment temperature increased but only in heat-treated WPC suspensions with 5% of TP.     

Effect of freezing on the viscoelastic behaviour of whey protein concentrate suspensions

The effect of freezing on viscoelastic behaviour of whey protein concentrate (WPC) suspensions was studied. Suspensions with total protein content of 5% and 9% w/v were prepared from a commercial WPC (unheated suspensions). A group of unheated suspensions was treated at two temperatures (72.5 and 77.5 °C) during selected times to obtain 60% of soluble protein aggregates (heat-treated suspensions). Unheated suspensions and heat-treated suspensions were frozen at −25 °C (frozen unheated and frozen heat-treated suspensions). Frequency sweeps (0.01–10 Hz) were performed in the region of linear viscoelasticity at 10, 20, 30, 40, and 50 °C. Mechanical spectra of all studied suspensions at 20 °C were similar to viscoelastic fluids and complex viscosity increased with the frequency (ω). Elastic (G′) and viscous (G″) moduli were modelled using power law equations (G′ = aω^x, G″ = bω^y), using fitted parameters a, x, b, and y for statistical analysis. Exponent y was the most influenced by freezing, indicating the existence of a higher degree of arrangement in frozen unheated suspensions and a lower degree of arrangement in frozen heat-treated suspensions. Only characteristic relaxation times (inverse of the crossover frequency) of suspensions with 5% w/v of total protein content were significantly influenced by freezing. Time–temperature superposition was satisfactory applied in unheated whey protein concentrate suspensions only in the range of high temperatures (30–50 °C). However, this principle failed over the complete temperature range in most of the frozen suspensions. It is possible that freezing produced an increase in the susceptibility to morphological changes with temperature during the rheological measurements.     

Use of Konjac glucomannan as additive to reinforce the gels from low-quality squid surimi

This paper reports a study of the influence of a Konjac glucomannan aqueous dispersion (KAD) as ingredient, at different alkalinity levels, on the thermal stability of low-quality squid surimi (Dosidicus gigas) and the viscoelastic properties of its gel. An increase in elastic (G^′) and viscous (G^″) moduli at T < 50 °C, reflecting protein aggregation, and a strong decrease at T > 50 °C, reflecting structural damage, were observed in thermal gelation profiles of low-quality squid surimi. The contribution of 1% KAD (10%) to enhancement of gelation ability was assessed by evaluating the viscoelastic properties of the gels, with and without KAD, at increasing alkalinity levels. Gels with KAD at high-pH had the best rheological properties. Small amplitude oscillatory shear (SAOS) tests showed a significant decrease in rigidity, an increase in strain amplitude and a decrease in the frequency-dependence of G^′ and G^″. These results were in agreement with instrumental texture analyses, meaning that KAD may be used to overcome the negative effect of the poor protein functionality of low-quality squid surimi and achieve better gels from them.     

Rheological behaviour of pullulanase-treated guar galactomannan on co-gelation with xanthan

The present study involves the use of non-specific enzyme pullulanase (from Bacillus acidopullulyticus) to remove galactose residues from guar galactomannan to obtain modified guar galactomannan mimicking the functional properties of locust bean gum. The modified guar galactomannan blended with xanthan exhibited the rheological behaviour of elastic modulus (G′) greater than viscous modulus (G″) with a decrease in tan δ value similar to locust bean gum/xanthan blend. Also a twofold increase in the magnitude of elasticity compared to xanthan alone suggested the synergistic interaction with formation of three dimensional networks. The modified guar galactomannan with galactose content of 21% and M:G ratio 1:3.8, almost akin to locust bean gum, showed a better interaction with xanthan. Dynamic stress sweep study of modified guar galactomannan/xanthan blend with increased yield stress of 800 dynes/cm² also indicated the synergistic behaviour. Modified guar galactomannan also revealed the maximum synergistic interaction with xanthan at a mixing temperature of 60 °C than at 20 °C, 30 °C, 40 °C and 50 °C, respectively. Modification of guar galactomannan by pullulanase is an alternative route to produce galactose-depleted guar galactomannan with enhanced rheological functionalities on co-gelation with xanthan, as a cost effective replacement to locust bean gum.     

Raman spectroscopic analysis and rheological measurements on natural actomyosin from haddock (Melanogrammus aeglefinus) during refrigerated (4 °C) and frozen (−10 °C) storage in the presence of trimethylamine-N-oxide demethylase from kidney of lizardfish (Saurida tumbil)

Changes in viscoelasticity and structure of haddock natural actomyosin (NAM) treated with partially purified trimethylamine-N-oxide demethylase (TMAOase) in the presence of cofactors (FeCl₂, ascorbate and cysteine), after refrigerated storage (4 °C) for 15 days or after frozen storage (−10 °C) for eight weeks, were elucidated using FT-Raman spectroscopy and dynamic viscoelastic measurement. Greater increases in the final storage modulus (G′) and loss modulus (G″), reflecting protein aggregation, were observed in the simulated NAM systems, containing NAM, trimethylamine oxide (TMAO) and cofactors, stored at −10 °C, compared to those stored at 4 °C, particularly in the system with a higher concentration of TMAOase (p < 0.05). Raman spectroscopy revealed that amide I and amide III bands of NAM were affected by TMAOase added as well as by storage temperature. The decrease in the CH₂ bending region near 1450 cm⁻¹, in the presence of TMAOase upon storage, suggested an increase in hydrophobic interactions of aliphatic residues. Changes in a doublet near 830 and 850 cm⁻¹ indicated an involvement of tyrosine residues as hydrogen bond donors in the system containing TMAOase after storage at both temperatures. The systems stored at −10 °C generally showed greater structural alteration than those kept at 4 °C, especially in the presence of 15 units of TMAOase/g. Therefore, TMAOase played an important role in the structural alteration and aggregation of haddock muscle proteins, mainly by the induction of formaldehyde formation.     

Steady and dynamic oscillatory shear rheological properties of ketchup-processed cheese mixtures: Effect of temperature and concentration

The steady and dynamic shear properties of ketchup-processed cheese (K-PC) mixtures were investigated at different temperatures (10-50 °C) and PC concentrations (0-30%). The K-PC mixtures showed a shear-thinning behavior with low magnitudes of yield stress. The consistency coefficient (K) and apparent viscosity (η₅₀) decreased with increase in temperature and concentration. The mixtures followed the Arrhenius temperature relationship, indicating that the magnitudes of activation energies (E_a) were in the range of 8.83-17.16 kJ mol⁻¹. Storage (G′), loss (G′′) and complex (G∗) modulus increased with increase in frequency while complex viscosity (η∗) decreased. The K-PC mixtures at concentrations of 0-15% exhibited weak gel-like behavior. Increase in the PC concentration resulted in a decrease in G∗, G′, G′′ and η∗ up to the 15% of PC concentration, showing a plateau value between 0% and 30% concentrations. Cox-Merz rule was not applicable to K-PC mixtures.     

Dielectric properties of soybean protein isolate dispersions as a function of concentration, temperature and pH

Dielectric properties of commercial soy protein isolate (SPI) dispersions were measured over the frequency range of 200-2500 MHz by the open-ended coaxial probe method using a network analyzer as a function of concentration (5, 10 and 15 g/100 g water), temperature (20-90 °C) and pH (4.5, 6.6 and 10). Results indicated that the dielectric constant (ε′) decreased with temperature (except at 90 °C) and frequency while increased with concentration. The loss factor (ε″) increased with frequency and concentration; however, temperature showed mixed effect. Both ε′ and ε″ data were related to frequency using a polynomial model. The significant change in ε′ and ε″ at 90 °C was a result of protein denaturation which was identified by differential scanning calorimetry (DSC). Change in the association/dissociation behavior of SPI dispersions due to electrostatic attraction/repulsion among protein molecules on heating as a function of pH was assumed to be responsible for the significant increase in dielectric parameters. Penetration depth (D_p) was estimated under various conditions and it decreased with an increase in frequency, concentration, temperature and pH. The minimum D_p was found at alkaline pH at a temperature of 90 °C and frequency of 2450 MHz.     

Starch–cassia gum interactions: A microstructure – Rheology study

We present for the first time the interactions of starch and cassia gum – a novel galactomannan recently approved for use in food processing. Viscoelastic, pasting and microstructural characterization of various starches (waxy; high amylose; normal; cross-linked waxy corn starch; potato starch) containing different levels of the cassia gum was carried out. Significant changes were observed in the morphology of granule remnants formed during gelatinization in the starch pastes prepared with and without the addition of cassia gum. The freeze-dried starch–cassia gum pastes presented a shrunken and tight arrangement of the starch granule remnants, when studied by scanning electron microscopy. A significant reduction in the granule remnant size was also calculated using laser diffraction particle size analysis. The extent of interaction with cassia gum differed significantly among the various starch types. All the unmodified corn starches recorded an increase in peak viscosity at all levels of the cassia gum addition. An increase in the final viscosity of these starches was also observed by the addition of cassia gum, with high amylose and normal corn starch showing the maximum. Similarly, the extent of breakdown and setback viscosity also differed among the different starch types. Ranges of dynamic rheological measurements (temperature, time and frequency sweeps) were performed within the viscoelastic zones. Rheological parameters, such as storage modulus (G′), loss modulus (G″) and the gelatinization temperature (T_gel), of the corn starches during the heating cycle were observed to increase, when cassia gum was present at lower levels. The starch–gum systems also exhibited higher tan δ values during both the heating and the cooling cycles, indicating the dominance of the viscous modulus. The G′ and G″ of all the corn starch gels containing cassia gum showed higher values throughout the frequency sweep range. However, the increase in G′ and G″ of different starches was not always consistent with the increase in cassia gum levels. The changes in rheological behaviour during storage of the starch gels, aged on the plate of the rheometer and then studied through time sweeps at 5 °C and frequency sweeps at 25 °C, suggested that the starch gels containing cassia gum had less pronounced changes in the rheological parameters than had their control counterparts.     

Rheology and functional properties of starches isolated from five improved rice varieties from West Africa

Starches were isolated from five improved rice varieties developed by West African Rice Development Agency (WARDA) namely FARO 32, FARO 51, FARO 52, FARO 54 and NERICA. Starch yield and amylose content varied between 73.77–70.02% and 22.88–24.48% respectively. Starches were polyhedral in appearances and within the size range 1.5–6.1 μm. The X-ray diffraction patterns of the starches show a peak centered on 2θ = 15.1°, a doublet on 17.1° and 18.1°, and another single peak at 23.12°. However, NERICA shows no doublet but a single peak at 2θ = 17.1° with a small shoulder. The peak viscosity of the starches ranged between 147.48 and 209.17 RVA corresponding to FARO 52 and NERICA respectively. A neat distinction is observed between the marked shear thinning of FARO 52 and the apparently plastic behavior of the other samples. Important differences appear in the low shear region where the viscosity increases in the following order: FARO 52 < FARO 54 < FARO 51 < FARO 32 < NERICA. The mechanical spectra exhibit similar profiles as the storage modulus (G′) prevails over the viscous component (G″) and is weakly dependent on the frequency. However, the storage modulus increases in the same order observed for low shear viscosity. The percentage retrogradation was between 61.9 and 86.6% and NERICA starch showed the least retrogradation indication. NERICA starch exhibited highest swelling and solubility, while the least was observed in FARO 52. Rheology and functional properties are dependent of amylose composition. This study provides knowledge for the utilization of starches isolated from improved rice varieties that would be relevant for both domestic and industrial applications.     

Dynamic oscillatory shear properties of O/W model system meat emulsions: Linear viscoelastic analysis for effect of temperature and oil concentration on protein network formation

Effects of oil concentration (57.50%, 58.75%, 60.00% and 61.25%) and temperature (5, 10 and 15 °C) on O/W model system meat emulsions were analyzed using oscillatory dynamic shear tests, allowing all emulsion systems to be characterized as linear viscoelastic solids exhibiting a pseudoplastic flow. The emulsion systems were characterized as weak gel-like macromolecular dispersions with G′ much greater than G″, exhibiting a plateau region. A modified Cox-Merz rule was applicable using shift factors. Frequency dependence of complex modulus (G^∗) was studied to measure strength of cross-linking protein network of the emulsion systems by calculating a practically constant order of the relaxation function (α = 0.10) and a concentration dependent stiffness parameter (A_α) using Friedrich and Heymann theory. It was concluded that the viscoelastic characteristics and strength of the emulsion systems increased with increasing oil level, but decreased with temperature. Different mathematical models were successfully constructed to predict the rheological parameters.     

Pasting and rheological behavior of soy protein-based pudding

Pasting and rheological behavior of pastes made from different commercial soy proteins and starches were investigated for the development of soy protein-based pudding system. Commercial starch Novation^® 2300 and soy protein concentrate Alpha^® 5812 were found to exhibit the most desirable pasting properties. The yield stress values of commercial puddings were in the range of 27.1-59.6 Pa, Consistency index (K) values in the range of 6.57-18.63 (Pa sⁿ) and flow behavior index (n) values in the range of 0.4192-0.6558. The K, and n values for soy protein-based puddings were found to be comparable to those for the commercial puddings. During 2 weeks of refrigeration, both G′ and G″ increased for all the puddings. Neither water separation nor net syneresis were observed for soy protein-based puddings during 2 weeks of storage at 5 °C. Further adjustments of the formulation that was more comparable to the commercial pudding were achieved.     

The impact of concentration,temperature and pH on dynamic rheology of psyllium gels

Structural aspects of the psyllium gum prepared from the seed husk of the plant of Plantago ovata Forsk was characterized by dynamic rheology and microscopy. Dynamic rheological properties of psyllium gel in the linear viscoelastic region, as a function of concentration (2, 2.5 and 3% w/w), temperature (5–95 °C) and pH (2.5–10) were investigated. Mechanical spectra of the psyllium gels were obtained by frequency sweep measurement classified into that of weak gels because G′ was larger than G″ throughout the tested frequency range and the separation of the two moduli (tan δ) was greater than 0.1. The phase angle increased with temperature and a peak associated with gel melting appeared at about 40 °C. All gels at different pH presented a typical weak gel spectrum. Scanning electron microscopy showed porous structures with different pore-size distribution for psyllium gels under different conditions in terms of concentration, pH and temperature.     

A rheological characterization of semi-solid dairy systems

Dispersions of cross-linked starch in full fat milk, taken as models of custard model systems, have been characterized by different rheological means: viscoelastic measurements, classical flow measurements and ‘vane’ rheometry. From viscosity measurements, the flow behaviour was described within the shear rate range 0.01–100 s⁻¹. The flow curves were fitted using the Herschell–Bulkley equation over the shear rate range 0.1–100 s⁻¹ while a deviation was found towards the low shear rate range, making the determination of the yield stress non realistic. Instead, measurements with the ‘vane’ device in low shear conditions provided a way to estimate the yield stress, at rest and after shearing, but the entire flow curve was not described. From the viscoelastic measurements at low strain amplitude, the mechanical spectra were obtained. Linearity tests beyond the linearity limits provided the critical stress corresponding to the G′–G″ cross-over. The parameters obtained from these different rheological methods are discussed.