Breakdown of Thixotropic Structure as Function of Time

Weltmann, Ruth N.

doi:10.1063/1.1714996

Cited by 156 publications

(63 citation statements)

References 15 publications

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“…2.5c) confirm the stability of these gels. The thixotropic behavior is best studied by tracking the material response resulting from stepwise changes in shear rate, as the coupled effect of time and shear rate can be clearly separated in such experiments [28,29]. Specific rheological test that is utilized to measure thixotropy is known as 3-interval thixotropy test (3-ITT) and it consists of 3 consecutive steps in control rate mode with alternating low and high shear rates [22].…”

Section: Flow Behaviormentioning

confidence: 99%

Natural Waxes as Oil Structurants

Patel

2015

Alternative Routes to Oil Structuring

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Wax-based oleogels display very interesting and complex rheological behavior; the physical gels of liquid oils created using natural waxes can be assumed to have characteristics of both the flocculated suspensions and semidilute polymer solutions. In this chapter, a comparative evaluation of six different natural waxes (with differing melting ranges) is described mainly with respect to their network forming properties at their respective minimum gelling concentrations to give the readers a comprehensive understanding of wax-based oleogels.Keywords Wax-based oleogels · Rheology · Microstructure · Cryo-SEM · Small amplitude oscillatory shear · Crystallization IntroductionAmong various structurants that are so far explored for gelling vegetable oils, natural waxes are considered to be the most promising ones because of their excellent oilbinding properties [1], economical value (capable of gelling oils at significantly lower concentrations, as low as 0.5 %wt) [2], and availability of a number of waxes that are approved for use in foods (albeit as indirect additives) [3,4]. Moreover, gels formed using waxes have interesting properties such as thermo-reversibility (gelsol transition as a function of temperature) [5,6] and stabilization of water-in-oil emulsions [7][8][9], which further justifies their popularity as structuring agents for edible oils.The enormous potential of waxes has been appreciated by many research groups and accordingly, the gelation behavior of waxes has been studied extensively with respect to the chemical properties of waxes (composition and impurities) [2], thermodynamics and kinetic aspects of wax crystallization (fractal aggregation, thermal properties, crystal morphology, and cooling rates) [1,10,11], and bulk response of gels to small and large deformations (rheology and texture analysis) [12][13][14].In this chapter, a comparative evaluation of six different natural waxes (with differing melting ranges) is described mainly with respect to their network forming properties at their respective minimum gelling concentrations to give the

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Section: Flow Behaviormentioning

confidence: 99%

Natural Waxes as Oil Structurants

Patel

2015

Alternative Routes to Oil Structuring

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“…In the Weltmann model, parameter A represents the initial shear stress and parameter B; the time coefficient of thixotropic breakdown, is ''the product of rate in breakdown of thixotropic structure and time of agitation at constant rate of shear'' (Weltmann, 1943). ANOVA results showed that sample-temperature interaction was significant for both parameters (F int ¼ 66:71; p ¼ 0:000 for parameter A and F int ¼ 18:29; p ¼ 0:000 for parameter B).…”

Section: Article In Pressmentioning

confidence: 99%

Flow behaviour of semi-solid dairy desserts. Effect of temperature

Tárrega

Durán

Costell

2004

International Dairy Journal

130

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“…The hysteresis area will give an estimate of the magnitude of the product thixotropy [7][8][9][10] . Modeling of the thixotropic behavior of food products has been based on equations, such as the Weltman model 11 , stress decay models 12 , and structural kinetic models 13 .…”

Section: Introductionmentioning

confidence: 99%

Effect of Concentration and Temperature on Flow Properties of Alyssum homolocarpum Seed Gum Solutions: Assessment of Time Dependency and Thixotropy

Koocheki

Razavi

2009

Food Biophysics

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Effects of different shear rates (14, 25, and 50 s −1 ), gum concentrations (3%, 3.5%, and 4%), and temperatures (5-65°C) on flow properties of Alyssum homolocarpum seed gum solutions were investigated using a rotational viscometer. The experimental data were fitted with three time-dependent rheological models, namely second-order structural kinetic model, Weltman model, and first-order stress decay model with a non-zero stress value. The rate constant and extent of viscosity strongly depended on the shear rate, gum concentration, and temperature. It was found that A. homolocarpum seed gum samples exhibited shear thinning and thixotropic behavior for all concentrations and temperatures. The amount of structural breakdown decreased with shear rate, but it did not have a general trend with concentration and temperature. The extent of thixotropy increased with increasing gum concentration and decreased with increasing temperature and shear rate. In this work, the decay rate constant generally increased with increasing shear rate; however, it did not have any trend with concentration and temperature.

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Breakdown of Thixotropic Structure as Function of Time

Cited by 156 publications

References 15 publications

Natural Waxes as Oil Structurants

Natural Waxes as Oil Structurants

Flow behaviour of semi-solid dairy desserts. Effect of temperature

Effect of Concentration and Temperature on Flow Properties of Alyssum homolocarpum Seed Gum Solutions: Assessment of Time Dependency and Thixotropy

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