scholarly journals Physicochemical Properties of Enzymatically Modified Starches

Processes ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 2251
Author(s):  
Abdellatif A. Mohamed ◽  
Husham Alqah ◽  
Mohammed S. Alamri ◽  
Shahzad Hussain ◽  
Akram A. Qasem ◽  
...  
Keyword(s):  
Physicochemical Properties ◽  
Flow Behavior ◽  
The Other ◽  
Arrhenius Model ◽  
Flow Curves ◽  
Flow Behavior Index ◽  
Excess Water ◽  
Modified Starches ◽  
Water Holding ◽  
Behavior Index

The physicochemical properties of native, annealed and enzyme-treated chickpea (CP), corn (CS), Turkish bean (TB) and sweet potato (SPS) were investigated. Germinated sorghum extract (GSET) was used as the source of enzymes. Starches were annealed in excess water by holding the slurry at 60 °C for 60 min with or without GSET. The flow curves/rheological data were fitted to the power law, Casson and Herschel–Bulkley models. Starches exhibited shear thinning behavior and a variation in the flow behavior index (n) (0.34–0.82) as a function of the starch type. The consistency index (k) of CP and CS decreased with annealing and GSET treatment but increased for TB and SPS. Annealed and GSET-treated SPS exhibited the highest yield stress compared to the other starches, except for CP. The temperature dependency of all starches was well described by the Arrhenius model (r2 = 0.88–0.99). The activation energy (Ea) values were in the range of 660–5359 (J/mol). The TB exhibited the most Ea and SPS the least. With the exception of SPS, annealing appeared to increase the Ea of all tested starches, but the range of Ea was broader for SPS and CS. Annealed and GSET starches exhibited an increase in the gelatinization temperatures (onset and peak) and a decrease in gelatinization enthalpy (ΔH). The syneresis and water holding capacity decreased after annealing or GSET treatment.

Effects of Greek Pomegranate Extracts in the Antioxidant Properties and Storage Stability of Kefir

2019 ◽  
Vol 15 (4) ◽  
pp. 437-441 ◽  
Author(s):  
Vasiliki Lagouri ◽  
Georgia Dimitreli ◽  
Aikatarini Kouvatsi
Keyword(s):  
Antioxidant Activity ◽  
Dairy Products ◽  
Storage Time ◽  
Storage Stability ◽  
Flow Behavior ◽  
Antioxidant Properties ◽  
Flow Behavior Index ◽  
Ph Values ◽  
Dpph Activity ◽  
Behavior Index

Background: Oxidation reactions are known to shorten the shelf life and cause damage to foods rich in fat, such as dairy products. One way to limit oxidation and increase the shelf life of fermented dairy products is to use natural antioxidants. The aim of this study was to examine the effect of adding pomegranate extracts in the antioxidant properties, rheological characteristics and the storage stability of the fermented product of kefir. Methods: The Pomegranate Juice (PGJ) and Peel Extracts (PGPE) (5%, 10% w/v) were added to kefir and the antioxidant properties were evaluated by using the methods of radical scavenging activity (DPPH) and Ferric Reducing Antioxidant Power Activity (FRAP). Spectrophotometric and instrumental methods were used to determine the Total Phenols (TPs), pH values, viscosity and flow behavioral index values of enriched with pomegranate kefir samples. The same properties were tested when kefir samples stored at 4°C for 7, 14, 21 and 28 days. Results: The addition of PGJ and PGPE results in an increase in the antioxidant activity (DPPH, FRAP) and total phenol content (TPs) of kefir samples. Increasing the concentration of the added PGJ and PGPE, results in an increase in the TP content and the DPPH activity of kefir. As far as the storage time is concerned, the results showed an increase in the amount of TP at 7th day and a reduction in the DPPH activity in the 14th day of storage. In contrary to the DPPH method, the increase in storage time has resulted in a reduction in antioxidant activity by the FRAP method. The addition of PGJ and PGPE in kefir results in a decrease in pH values while the pH of kefir samples increased during storage at 4°C for 28 days. The addition of PGJ and PGPE to kefir samples results to a decrease in viscosity and an increase in the flow behavior index. Increasing storage time results in increased flow behavior index of kefir samples. Conclusion: The addition of PGJ and PGPE increased the antioxidant activity and total phenols of the kefir product and preserved its properties during the total storage time of 28 days at 4°C.

Electroosmotic Flow of Power-Law Fluids in a Slit Microchannel

2009 ◽  
Author(s):  
Cunlu Zhao ◽  
Chun Yang
Keyword(s):  
Shear Stress ◽  
Double Layer ◽  
Power Law ◽  
Dynamic Viscosity ◽  
Electroosmotic Flow ◽  
Flow Behavior ◽  
Flow Behavior Index ◽  
Power Law Fluids ◽  
Hyperbolic Cosine ◽  
Behavior Index

Electroosmotic flow of power-law fluids in a slit channel is analyzed. The governing equations including the linearized Poisson–Boltzmann equation, the Cauchy momentum equation and the continuity equation are solved to seek analytical expressions for the shear stress, dynamic viscosity and velocity distributions. Specifically, exact solutions of the velocity distributions are explicitly found for several special values of the flow behavior index. Furthermore, with the implementation of an approximate scheme for the hyperbolic cosine function, approximate solutions of the velocity distributions are obtained. In addition, a mathematical expression for the average electroosmotic velocity is derived for large values of the dimensionless electrokinetic parameter, κH, in a fashion similar to the Smoluchowski equation. Hence, a generalized Smoluchowski velocity is introduced by taking into account contributions due to the finite thickness of the electric double layer and the flow behavior index of power-law fluids. Finally, calculations are performed to examine the effects of κH, flow behavior index, double layer thickness, and applied electric field on the shear stress, dynamic viscosity, velocity distribution, and average velocity/flow rate of the electroosmotic flow of power-law fluids.

Shear Rate Corrections for Herschel-Bulkley Fluids in Couette Geometry

2008 ◽  
Vol 18 (3) ◽  
pp. 34482-1-34482-11 ◽  
Author(s):  
Vassilios C. Kelessidis ◽  
Roberto Maglione
Keyword(s):  
Flow Behavior ◽  
Flow Equation ◽  
Oil Field ◽  
Rheological Parameters ◽  
Concentric Cylinder ◽  
Flow Behavior Index ◽  
Shear Rates ◽  
Power Law Fluids ◽  
Good Agreement ◽  
Behavior Index

AbstractA methodology is presented to invert the flow equation of a Herschel-Bulkley fluid in Couette concentric cylinder geometry, thus enabling simultaneous computation of the true shear rates, γ̇HB, and of the three Herschel-Bulkley rheological parameters. The errors made when these rheological parameters are computed using Newtonian shear rates, γ̇N, as it is normal practice by research and industry personnel, can then be estimated. Quantification of these errors has been performed using narrow gap viscometer data from literature, with most of them taken with oil-field rheometers. The results indicate that significant differences exist between the yield stress and the flow behavior index computed using γ̇HB versus the parameters obtained using γ̇N and this is an outcome of the higher γ̇HB values. Predicted true shear rates and rheological parameters are in very good agreement with results reported by other investigators, who have followed different approaches to invert the flow equation, both for yield-pseudoplastic and power-law fluids.

scholarly journals Initial Self-Healing Temperatures of Asphalt Mastics Based on Flow Behavior Index

Materials ◽  
2018 ◽  
Vol 11 (6) ◽  
pp. 917 ◽  
Author(s):  
Chao Li ◽  
Shaopeng Wu ◽  
Guanyu Tao ◽  
Yue Xiao
Keyword(s):  
Flow Behavior ◽  
Self Healing ◽  
Flow Behavior Index ◽  
Asphalt Mastics ◽  
Behavior Index

Non-Newtonian Flow Behavior on Frictional Pressure in Packed Bed

2011 ◽  
Vol 9 (1) ◽  
Author(s):  
Suresh Kumar Patel ◽  
Subrata Kumar Majumder
Keyword(s):  
Pressure Loss ◽  
Liquid Velocity ◽  
Flow Behavior ◽  
Scale Up ◽  
Packed Bed ◽  
Newtonian Liquid ◽  
Newtonian Flow ◽  
Flow Behavior Index ◽  
Ergun Equation ◽  
Behavior Index

The packed bed columns with non-Newtonian liquid are increasing importance as a simple and inexpensive means of achieving yield of different chemical and biochemical processes though their hydrodynamic behavior is complex and not yet fully understood. In this article non-Newtonian flow behavior on frictional pressure was investigated in packed bed within a range of liquid velocity 0.004-0.04 m/s. The frictional pressure loss in non-Newtonian liquid system has been analyzed by modified Ergun equation. The modification of the Ergun equation is incorporated with the flow behavior index of non-Newtonian liquid. The degree of frictional pressure loss decreases with increase in flow behavior index. A correlation has been developed to interpret the degree of effect on the frictional pressure loss. The correlation may be useful for further understanding and scale-up of the packed bed column for its industrial application.

Rheological Properties of Butia Pulp

2006 ◽  
Vol 2 (1) ◽  
Author(s):  
Charles Windson Isidoro Haminiuk ◽  
Maria-Rita Sierakowski ◽  
Giselle Maria Maciel ◽  
José Raniere Mazile Bezerra Vidal ◽  
Ivanise Guilherme Branco ◽  
...  
Keyword(s):  
Yield Stress ◽  
Apparent Viscosity ◽  
Good Description ◽  
Flow Behavior ◽  
Rheological Parameters ◽  
Concentric Cylinder ◽  
Flow Behavior Index ◽  
Different Temperatures ◽  
Stress Flow ◽  
Behavior Index

Rheological parameters of Butia pulp were determined at different temperatures using a concentric cylinder Haake Rotovisco rheometer, model RV-20, with measurement system ZA-30. Butia pulp was found to exhibit non-Newtonian, pseudoplastic behavior at all temperatures and the rheological parameters were adequately described by the Herschel-Bulkley model. Yield stress, flow behavior index, and consistency coefficient were significantly affected by temperature. The yield stress decreased exponentially with process temperature and ranged between 36.60 and 21.70 Pa. Apparent viscosity calculated through the Herschel-Bulkley model decreased with an increase in temperature. The Arrhenius model gave a good description of temperature effect on apparent viscosity of the pulp.

Non-Newtonian Fluid Flow and Heat Transfer in a Semicircular Microtube Induced by Electroosmosis and Pressure Gradient

2018 ◽  
Vol 140 (12) ◽  
Author(s):  
Mehdi Karabi ◽  
Ali Jabari Moghadam
Keyword(s):  
Nusselt Number ◽  
Pressure Gradient ◽  
Flow Behavior ◽  
Velocity Ratio ◽  
Shear Thinning ◽  
Fluid Viscosity ◽  
Flow Behavior Index ◽  
Shear Thinning Fluids ◽  
Power Law Fluids ◽  
Behavior Index

The hydrodynamic and thermal characteristics of electroosmotic and pressure-driven flows of power-law fluids are examined in a semicircular microchannel under the constant wall heat flux condition. For sufficiently large values of the electrokinetic radius, the Debye length is thin; the active flow within the electric double layer (EDL) drags the rest of the liquid due to frictional forces arising from the fluid viscosity, and consequently a plug-like velocity profile is attained. The velocity ratio can affect the pure electrokinetic flow as well as the flow rate depending on the applied pressure gradient direction. Since the effective viscosity of shear-thinning fluids near the wall is quite small compared to the shear-thickening fluids, the former exhibits higher dimensionless velocities than the later close to the wall; the reverse is true at the middle section. Poiseuille number increases with increasing the flow behavior index and/or the electrokinetic radius. Due to the comparatively stronger axial advection and radial diffusion in shear-thinning fluids, better temperature uniformity is achieved in the channel. Reduction of Nusselt number continues as far as the fully developed region where it remains unchanged; as the electrokinetic radius tends to infinity, Nusselt number approaches a particular value (not depending on the flow behavior index).

scholarly journals Uncertainties quantification and modelling of different rheological models in estimation of pressure losses during drilling operation

2018 ◽  
Vol 7 (2) ◽  
pp. 694 ◽  
Author(s):  
Anawe P. A. L ◽  
Folayan J. Adewale
Keyword(s):  
Power Law ◽  
Averaging Method ◽  
Graphical Method ◽  
Flow Behavior ◽  
Drilling Fluids ◽  
Flow Behavior Index ◽  
Rheological Models ◽  
Pressure Losses ◽  
Pump Pressure ◽  
Behavior Index

The determination of pressure losses in the drill pipe and annulus with a very high degree of precision and accuracy is sacrosanct for proper pump operating conditions and correct bit nozzle sizes for maximum jet impact and forestalling of possible kicks and eventual blow outs during drilling operation. The two major uncertainties in pump pressure estimation that are being addressed in this research work are the flow behavior index (n) and the consistency index factor (k). It is in this light that the accuracy of various rheological models in predicting pump pressure losses as well as the uncertainties associated with each model was investigated. In order to come by with a decisive conclusion, two synthetic based drilling fluids were used to form synthetic muds known as sample A and B respectively. Inference from results shows that the Newtonian model underestimated the pump pressure by 78.27% for sample A and 82.961% by for sample B. While the Bingham plastic model overestimated the total pump pressure by 100.70% for sample A and 48.17% for sample B. Three different power law rheological model approaches were used to obtain the flow behavior index and consistency factor of the drilling fluids. For the power law rheological model approaches, an underestimation error of 23.5743% was encountered for the Formular method for sample A while the proposed consistency index averaging method reduces the error to 14.9306%. The Graphical method showed a reasonable degree of accuracy with underestimation error of 5.6435%. Sample B showed an underestimation error of 47.8234% by using the power law formula method while the Consistency averaging method reduced the error to 20.7508. The graphical method showed an underestimation error of 0.4318%.

scholarly journals Use of Gum Cordia (Cordia myxa) as a Natural Starch Modifier; Effect on Pasting, Thermal, Textural, and Rheological Properties of Corn Starch

Foods ◽  
2020 ◽  
Vol 9 (7) ◽  
pp. 909
Author(s):  
Shahzad Hussain ◽  
Abdellatif A. Mohamed ◽  
Mohamed Saleh Alamri ◽  
Mohamed A. Ibraheem ◽  
Akram A. Abdo Qasem ◽  
...  
Keyword(s):  
Corn Starch ◽  
Flow Behavior ◽  
Textural Properties ◽  
Flow Behavior Index ◽  
Modification Method ◽  
Cordia Myxa ◽  
Gum Cordia ◽  
The Stability ◽  
Starch Gels ◽  
Behavior Index

Incorporation of hydrocolloid gums in native starches help to improve their pasting, thermal, rheological and textural properties along with improvement in the stability of starch gels. The use of Cordia gum is not widely studied as a starch modifier and this fact could make this study more interesting and unique. This study investigated the effects of the non-conventional hydrocolloid gum (Cordia gum) on corn starch properties. Corn starch and gum Cordia (GC) blends were prepared at different replacement levels (0%, 3%, 6%, 9%, and 12%). The effect of GC levels on pasting, thermal, rheological, and textural properties were evaluated using rapid viscoanalyzer, differential scanning colorimeter, rheometer, and texture analyzer. The presence of GC significantly increased starch gelatinization temperatures, enthalpies, peak viscosities, final viscosities, and setback viscosities. GC improved freeze thaw stability in starch. The shear rate (1/s) versus shear stress (σ) data of all samples fitted well to the simple power law model (R2 = 0.97–0.99). The control had the lowest flow behavior index (n; 0.17), which increased to (0.36–0.56) with increasing GC levels. The consistency index (K) of the starch-gum blends increased with increasing GC levels. The dominance of elastic properties over viscous properties was demonstrated by G′ > G″. The magnitudes of G′ and G″ increased with increasing GC concentration. The outcomes could help to use this modification method as an alternative to chemical and enzymatic modification with respect to cost, safety, less time consumption and less requirement of process modifications.

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