Rheological Properties of Cooking Creams: Effect of Freeze-Thaw Treatment

2007 ◽  
Vol 3 (3) ◽  
Author(s):  
Angeles Cancela ◽  
Rocio Maceiras ◽  
Nathalie Delgado-Bastidas ◽  
Estrella Alvarez
Keyword(s):  
Activation Energy ◽  
Shear Stress ◽  
Frozen Storage ◽  
Rheological Behaviour ◽  
Rheological Characteristics ◽  
Concentric Cylinder ◽  
Freeze Thaw ◽  
Rheological Measurements ◽  
Treated Sample ◽  
Freezing Cycle

Rheological characteristics of commercial creams were investigated at different freeze-thaw conditions. This study was carried out to determine the effect of the freeze-thaw treatment on rheological behaviour and the activation energy in different commercial creams. Freeze-thaw treatment was made at different times of frozen storage within a range from 0 to 6 weeks. For each freezing cycle, the sample was submitted to rheological measurements within range of temperature between 20 and 40° C. A rotational, concentric cylinder viscosimeter Viscotester VT550 (Germany) type Searle was used in this work. The apparent viscosity is defined as the ratio of shear stress and shear rate, which was varied between 17.8 and 445 s-1. The Power Law or Oswaltd Waele model describes well the rheological behaviour of the analyzed samples. Furthermore, in all cases sample viscosity increased when was exposed to freeze-thaw treatment with respect to the not treated sample. And other hand, the activation energy has high values; hence there is clear evidence that the rheological behaviour presents a high dependence with the temperature.

scholarly journals FEATURES OF RHEOLOGY OF AGAR-AGAR SOLUTIONS

2018 ◽  
pp. 53-60
Author(s):  
Борис (Boris) Павлович (Pavlovich) Шипунов (Shipunov) ◽  
Виталий (Vitalii) Евгеньевич (Evgen'evich) Коптев (Koptev) ◽  
Вадим (Vadim) Иванович (Ivanovich) Маркин (Markin)
Keyword(s):  
Activation Energy ◽  
Shear Stress ◽  
Structural Change ◽  
Temperature Increase ◽  
Rheological Behaviour ◽  
Similar Type ◽  
Shear Speed ◽  
Smooth Dependence ◽  
Mechanical Influence ◽  
Two Temperature

The article presents the results of experiments on studying of rheological behaviour of dilute solutions of agar-agar. The chosen range of concentration 0,1–0,7% allows to avoid gelation at ambient temperature. Dependence of viscosity and shear stress on concentration, shearing speed and temperature in an interval 25–45 °С is investigated. It was found that the concentration dependence of viscosity severely depends  on the shear speed, a nonlinearity is observed that increases with decreasing shear speed. The dependence of the viscosity on the shear speed for concentrations of 0,3–0,7% has a similar but gradually changing type of the asymptotic decrease, whereas for 0,1%, solution dependence linearly grows with increase of shear speed. The interrelation of viscosity and shear stress is studied. Curves for solutions of 0,3–0,7% have a similar type and differ significantly from curves for 0,1% solutions. Moreover, the dependencies are not typical for polymer solutions. The activation energy of viscosity and shear stress is studied. For two temperature intervals: 25–35 and 35–45 °C, there is no correlation and a smooth dependence of the measured parameters on temperature. The activation energy of both viscosity and shear stress not decreases with temperature increase, as one might expect, but increases, for many times. This fact is observed completely individually for the different concentrations. An explanation is proposed for the observed dependences, which is based on the assumption of a structural change in agar-agar solutions, which is caused by changing the concentration of solution and magnitude of the mechanical influence.

scholarly journals Non-Isothermal Models to Determine the Rheological Constants of Different Kuwaiti Crude Oils

2021 ◽  
Author(s):  
Bader Albusairi ◽  
◽  
Adam Al-Mulla ◽  
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Shear Stress ◽  
Shear Rate ◽  
Crude Oils ◽  
Rheological Characteristics ◽  
Exponential Factor ◽  
Empirical Relations ◽  
Eyring Equation ◽  
Statistical Estimations

The rheological characteristics of four Kuwaiti crude oils samples collected from four different collection points; namely, MG 23T, MG 29T, MG 34T and MG 108T were investigated. The investigation were conducted in the temperature range 298–313 K using the Bingham, Ostwald–de Waele, Herschel–Bulkley, Casson, and modified Casson models. The experimental data of the shear stress were modeled as a function of the shear rate and temperature. Statistical estimations were used to determine the most accurate model and non-isothermal empirical relations. The Ostwald–de Waele and Herschel–Bulkley models yielded the most accurate predictions for MG 23T, MG 29T and MG 108T, and MG 34T, respectively. It is noted that all the crude oils follow shear thinning behavior. Arrhenius-Eyring equation has been used to estimate the activation energy and the pre-exponential factor of these crude oils at a shear rate of 10.3 s-1.

Shear Loss Characteristics of an Aerobic Biofilm

1992 ◽  
Vol 26 (3-4) ◽  
pp. 595-600 ◽  
Author(s):  
S. M. Rao Bhamidimarri ◽  
T. T. See
Keyword(s):  
Growth Rate ◽  
Shear Stress ◽  
Film Thickness ◽  
Removal Rate ◽  
Surface Growth ◽  
Phenol Removal ◽  
Concentric Cylinder ◽  
Substrate Utilisation ◽  
Utilisation Rate ◽  
Net Growth Rate

Growth and shear loss characteristics of phenol utilizing biofilm were studied in a concentric cylinder bioreactor. The net accumulation of the biofilm and the substrate utilisation were measured as a function of torque. Uniform biofilms were obtained up to a thickness of around 300 microns, beyond which the surface growth was non-uniform. The substrate utilisation rate, however, reached a constant value beyond film thickness of 50 to 100 microns depending on the operational torque. The maximum phenol removal rate was achieved at a shear stress of 3.5 Nm-2. The effect of shear stress on net growth rate was found to be described byand a zero net growth was obtained at a shear stress of 18.7 Nm-2.

A NEW ORGANIC/INORGANIC HYBRID WITH HIGH ELECTRORHEOLOGICAL ACTIVITY

2002 ◽  
Vol 16 (17n18) ◽  
pp. 2454-2460 ◽  
Author(s):  
X. P. ZHAO ◽  
X. DUAN
Keyword(s):  
Activation Energy ◽  
Shear Stress ◽  
Necessary Conditions ◽  
Sol Gel ◽  
Root Temperature ◽  
Sedimentation Stability ◽  
Inorganic Hybrid ◽  
Active Particles ◽  
Static Shear

In-situ sol-gel method to prepare colloidal hybrids of surfactant modified polysucchride and titanium oxide has been presented, and experiments indicated these highly ER active particles exhibited a remarkable ER effect. The static shear stress can be up to 37 k Pa (shear rate 5 S -1) under DC field of 4 kV/mm at root temperature, well above that of simple blends of starch and TiO 2. In the meanwhile, temperature dependence and sedimentation stability were also greatly improved. Based on recent experimental facts, we find that dielectric properties and surface (interface) activity are two necessary conditions fulfilling the requirement of high ER activity. Adequate grinding of particles with oil can effectively enhance the shear stress, which may be owed to the decline of the activation energy needed for restructuring. It has provided us a new horizon for preparation of excellent ER materials and further studies should be continued to make.

Investigation on the Rheological Behavior of Polyamide6/Montmorillonite Nanocomposites by Reactive Extrusion

2011 ◽  
Vol 233-235 ◽  
pp. 1998-2001 ◽  
Author(s):  
Ming Zhao ◽  
Xiao Zhong Lu ◽  
Kai Gu ◽  
Xiao Min Sun ◽  
Chang Qing Ji
Keyword(s):  
Activation Energy ◽  
Shear Stress ◽  
Shear Rate ◽  
Rheological Behavior ◽  
Reactive Extrusion ◽  
Shear Thinning ◽  
Experimental Results ◽  
Montmorillonite Nanocomposites

The rheological behavior of PA6/montmorillonite(MMT) by reactive extrusion was investigated using cone-and-plate rheometer. The experimental results indicated that PA6/MMT exhibited shear-thinning behavior. The shear stress of both neat PA6 and PA6/MMT increased with the increase in the shear rate. The reduction of the viscous activation energy with the increase of shear stress reflected PA6/MMT can be processed over a wider temperature.

ENTROPY INFLUENCE ON THE DEPENDENCE OF THE NANOFLUIDS VISCOSITY ON TEMPERATURE AND SHEAR RATE

2021 ◽  
Vol 7 (3) ◽  
pp. 89-105
Author(s):  
Lyudmila P. SEMIKHINA ◽  
Daniil D. Korovin
Keyword(s):  
Activation Energy ◽  
Shear Stress ◽  
Shear Rate ◽  
Viscous Flow ◽  
High Reliability ◽  
Narrow Particle Size Distribution ◽  
Disperse Systems ◽  
Rotational Viscometer ◽  
Surfactant Micelles ◽  
Dispersed Systems

A Brookfield DV-II + Pro rotational viscometer was used to study the viscosity of 7 samples of concentrated nanodispersed systems (nanofluids) with a similar viscosity (6-22 mPa ∙ s), the particles of the dispersed phase in which are nanosized surfactant micelles and conglomerates from them. It was found that for 5 out of 7 studied reagents, there is a decrease in viscosity typical for dispersed systems with an increase in the shear rate, and their flow curves, that is, the dependence of the shear stress on the shear rate, correspond to the ideal plastic flow of non-Newtonian fluids. Moreover, with high reliability, R2 ≥ 0.999 is described by the Bingham equation with a small value of the limiting shear stress (less than 0.2 Pa). It is shown that all the studied reagents are also characterized by an increase in the activation energy of a viscous flow Е with an increase in the shear rate. As a result, a decrease in viscosity with an increase in shear rate, typical for disperse systems, including nanofluids, is provided by a more significant increase in entropy changes ΔS compared to Е. It has been substantiated that, depending on the ratio between the activation energy of viscous flow Е and the change in entropy ΔS, the viscosity of concentrated micellar dispersed systems with an increase in the shear rate can decrease, remain unchanged, and increase. The last two cases, not typical for disperse systems and nanofluids, were identified and studied using the example of two demulsifiers, RIK-1 and RIK-2, with a maximum of a very narrow particle size distribution at 160 ± 5 nm, corresponding to the size of a special type of very stable micelles Surfactant — vesicle.

Flow Properties of Utah Shale Oils

1981 ◽  
Vol 21 (06) ◽  
pp. 679-686 ◽  
Author(s):  
W.H. Seitzer
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Pour Point ◽  
Water Solution ◽  
Shale Oil ◽  
Concentric Cylinder ◽  
Long Distance ◽  
Time Calibration ◽  
The Difference ◽  
Cylinder Viscometer

Abstract In a concentric cylinder viscometer. Utah shale oils have different characteristics, both at equilibrium flow and during start-up from rest, depending on whether the wax has crystallized as needles or spherulites. Compared with waxy crude oils, which are thixotropic, shale oil had the added rheological property of being antithixotropic. Introduction The most likely liquid synthetic fuel to be produced initially in the U.S. will be raw shale oil from western oil shale. This abundant resource is located principally in the western Rocky Mountain states of Colorado. Utah. and Wyoming (Fig. 1). Ultimate commercial production probably will be transported to marketing, distribution, and refining centers by pipeline. It has been reported that Utah shale oils produced by the Union "B" and Paraho DH retorting processes gave similar physical and chemical properties. Some properties of the two Utah shale oils are given in Table 1. The only major difference is that the Union shale oil has a pour point of - 1 degree C compared with a pour point of 25 degrees C for the Paraho oil. Wax Crystallization The difference in the pour points of the oils from the Utah shale retorted by Union Oil Co of California and Paraho is caused mainly by the difference in how the wax in the respective oils crystallizes. In the high- pour-point (25 degrees C) Paraho DK oil, the wax, under a microscope, appears as fine (1 to 10 m) needles, as expected for normal paraffins. However, the wax in the low-pour-point (−1 degrees C) Union oil forms small spherulites.Wax spherulites have not been reported before: however, this type of crystal is seen commonly in polymer. Spherulites show up as round areas containing a maltese cross when observed between crossed polars under a microscope.Photomicrographs of these crystals are shown in Figs. 2 and 3. The former, showing spherulites, is of the Union oil. In contrast, they are very different from the customary needles as typified by the Paraho oil in the latter micrograph. Presumably, these highly ordered spheres are made up of wax needles grown out radially from the center as described by Hartshorne and Stuart. The polarized light is scattered only by those needles not parallel nor perpendicular to the plane of polarization. Viscometer Measurements To understand the effect of these spherulites on the flow characteristics of raw shale oil at flow conditions expected in a long-distance pipeline, typical stress-rate measurements were made in a rotating cylinder viscometer, the Haake Rotovisco RV3 with MK500 measuring head and MVI coaxial cylinder sensor having an 82-mm cup and radii ratio of 0.95. This equipment has provisions for varying shear rate continuously at selected values down to 23.4 sec(−1)/min and can produce and record shear stress as a function of either shear rate or time. Calibration of the sensor was verified with a sucrose/water solution at several temperatures.Changes in temperature always were made from lower to higher to keep the sensor full of oil. Also, the shear-stress/ shear-rate curves were obtained by starting at high shear, down to zero, and then back up. SPEJ P. 679^

Storage Life of Refrozen Silver Hake (Merluccius bilinearis) Processed as Fillets am Minced Flesh from Thawed, Stored, Round-Frozen Fish

1977 ◽  
Vol 34 (12) ◽  
pp. 2369-2373 ◽  
Author(s):  
Doris Fraser Hiltz ◽  
D. H. North ◽  
Barbara Smith Lall ◽  
R. A. Keith
Keyword(s):  
Key Words ◽  
Frozen Storage ◽  
Storage Life ◽  
Freeze Thaw ◽  
Acceptable Quality ◽  
Frozen Fish ◽  
Silver Hake ◽  
Merluccius Bilinearis ◽  
Protein Extractability

Refrozen silver hake (Merluccius bilinearis), processed as fillets and minced flesh after thawing of stored round fish that had been frozen within 14 h of capture, underwent rapid deterioration during storage at −18 °C compared with once-frozen control materials from the same lot of fish. The estimated maximum storage life of silver hake refrozen as fillets after 3 and 6 mo storage of the round fish at −25 °C was reduced to about 4.5 and 1 mo, respectively, from 10 mo for once-frozen control fillets. Quality of the refrozen materials immediately after thawing and refreezing was similar to that of the round-frozen fish, except after 6 mo, where some initial deterioration occurred, particularly in minced flesh. Minced flesh was more unstable in frozen storage than fillets. In all once- and twice-frozen materials, formation of dimethylamine occurred concomitantly with decrease in protein extractability. Round-frozen fish underwent no loss in protein extractability during 6 mo storage at −25 °C, but some lipid hydrolysis occurred. These results suggest that the freeze–thaw–refreeze process as applied to silver hake will yield a final product of acceptable quality provided that storage of the round fish does not exceed 3–4 mo and that the refrozen materials are marketed within a month after processing. Key words: silver hake, Merluccius bilinearis, refrozen storage, dimethylamine, minced flesh

Residual Triose Phosphate Isomerase Activity and Color Measurements to Determine Adequate Cooking of Ground Beef Patties†

1999 ◽  
Vol 62 (2) ◽  
pp. 156-161 ◽  
Author(s):  
ARNIE I. SAIR ◽  
ALDEN M. BOOREN ◽  
BRADFORD W. BERRY ◽  
DENISE M. SMITH
Keyword(s):  
Frozen Storage ◽  
Ground Beef ◽  
Past Research ◽  
Triose Phosphate Isomerase ◽  
Department Of Agriculture ◽  
Freeze Thaw ◽  
Triose Phosphate ◽  
Isomerase Activity ◽  
Beef Patties ◽  
Cooking Temperature

The objectives were to (i) compare the use of triose phosphate isomerase (TPI) activity and internal color scores for determination of cooking adequacy of beef patties and (ii) determine the effect of frozen storage and fat content on residual TPI activity in ground beef. Ground beef patties (24.4% fat) were cooked to five temperatures ranging from 60.0 to 82.2°C. TPI activity decreased as beef patty cooking temperature was increased from 60.0 to 71.1°C; however, no difference (P > 0.05) in activity (6.3 U/kg meat) was observed in patties cooked to 71.1°C and above. Degree of doneness color scores, a* values and b* values, of ground beef patties decreased as internal temperature was increased from 60.0 to 71.1°C; however, temperature had no effect on L* values. TPI activity in raw ground beef after five freeze–thaw cycles did not differ from the control. Three freeze–thaw cycles of raw ground beef resulted in a 57.2% decrease in TPI activity after cooking. TPI activity of cooked beef increased during 2 months of frozen storage, but TPI activity in ground beef stored for 3 months or longer did not differ from the unfrozen control. While past research has shown color to be a poor indicator of adequate thermal processing, our results suggest that undercooked ground beef patties could be distinguished from those that had been adequately cooked following U.S. Department of Agriculture guidelines using residual TPI activity as a marker.

scholarly journals RHEOLOGICAL ANALYSIS OF VEGETABLE OILS USED FOR BIODIESEL PRODUCTION IN BRAZIL

2015 ◽  
Vol 14 (2) ◽  
pp. 31 ◽  
Author(s):  
L. E. Silva ◽  
C. A. C. Santos ◽  
J. E. S. Ribeiro ◽  
C. C. Souza ◽  
A. M. S. Sant’Ana
Keyword(s):  
Shear Stress ◽  
Rheological Properties ◽  
Vegetable Oils ◽  
Rheological Behavior ◽  
Apparent Viscosity ◽  
Biodiesel Production ◽  
Viscosity Data ◽  
Concentric Cylinder ◽  
Lower Shear ◽  
Different Temperatures

Rheology attempts to define a relationship between the stress acting on a given material and the resulting deformation and/or flow that takes place. Thus, the knowledge of rheological properties of fluid materials such as vegetable oils generates auxiliary data that can be used in its storage and application. In this context, the aim of this study was to evaluate the rheological behavior of vegetable oils (cotton, canola, sunflower, corn and soybean) at different temperatures, using four rheological models (Ostwald- de-Waelle, Herschel-Bulkley, Newton and Bingham). The rheological properties were determined using a Thermo Haake rheometer with concentric cylinder geometry. Measurements were taken at 30, 45 and 60 °C by controlling the temperature using a thermostatic bath coupled to the equipment. The software Rheowin Pro Job Manager was used for process control and data record. The rheograms were obtained by measuring the values of shear stress varying the shear rate from 100 to 600 s-1 within 250 seconds. For the analysis of the apparent viscosity at different shear rates was applied simple linear regression until 2nd degree with the aid of SAS (SAS/Stat 9.2) program. The apparent viscosity data were submitted to analysis of variance and the averages were compared by Tukey test at 5% of probability. Higher temperatures of the samples were correlated to lower shear stress values, hence lower values for viscosity and consistency index were obtained, since it is known that the density and viscosity are highly sensitive to temperature and that the increase in temperature results in reduction of viscosity, benefiting the fluid flow. The models of Newton and Ostwald-de-Waelle were chosen to evaluate the rheological behavior of the samples, showing a good fit for the rheological data.

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