Comparative study of the physicochemical properties of a vegan dressing-type mayonnaise and traditional commercial mayonnaise

The food industry has developed a vegan dressing-type mayonnaise due to new consumer demands. The aim of this study was to compare three commercial mayonnaise types with a vegan dressing, measuring their physicochemical properties. Four dressing samples were analyzed: vegan, homemade recipe, creamy, and light. The following properties were measured: water activity, color, droplet size, rheological properties, structural analysis, and oxidative stability. A high color difference was observed between vegan and the other samples due to the presence of chickpea protein. The size and distribution of droplets of the vegan sample were greater than the others. The rheological properties indicated that all samples are non-Newtonian pseudoplastic fluids. The FT-IR results indicated that the highest peak for vegan corresponded to its content in mono-unsaturated fat. Therefore, it showed the lowest oxidative stability. In conclusion, the mayonaise formulations were affected by physicochemical properties such as the content and composition of the oil, thickener and protein contents, along with processing technology.

Effects of Surface Roughness and Supply Inertia on Steady Performance of Hydrostatic Thrust Bearings Lubricated with Non-Newtonian Fluids

The objective of present theoretical analysis is to study the combined effects of surface roughness and fluid inertia (including the inertia of the fluid in the supply region) on the steady performance of stepped circular hydrostatic thrust bearings lubricated with non-Newtonian pseudoplastic fluids using Rabinowitsch stress-strain model. To account for the effects of surface roughness, the classical Christensen theory of rough surface has been taken. Analytic expressions for film pressure in bearing regions have been established for radial and circumferential patterns of roughness. Numerical results for film pressure, load carrying capacity and lubricant flow rate has been plotted and analysed. Due to surface roughness and fluid inertia in overall regions, significant improvement in performance properties have been observed.

Approaches to increasing the heat stability of whey proteins

В работе обобщаются новейшие теоретические подходы к регулированию термических реакций денатурации и агрегации сывороточных белков, включая физические, химические, ферментативные, а также комбинации различных методов. Описывается поведение модифицированных сывороточных белков во время термической обработки. Среди физических способов модификации приведены существующие технологии обработки сывороточных белков с использованием ультразвука, а также обработки белка под высоким давлением в сочетании с предварительным нагревом. В обзоре подчеркивается, что любая химическая модификация сывороточных белков осуществляется посредством нарушения структуры белка за счет блокирования свободных сульфгидрильных групп. Приводятся такие способы повышения термостойкости, как создание белково-полисахаридных комплексов, которые при pH, близких к изоэлектрической точке, проявляют характеристики псевдопластических жидкостей. В обзоре отмечается способность реакции гликирования также повышать термическую стойкость сывороточных белков. Подчеркивается перспективность ферментативной модификации сывороточных белков в пищевой промышленности, способствующей повышению как термостабильности, так и растворимости белков в кислых значениях pH из-за потери вторичной структуры. Отмечается возможность применения продуктов гидролиза, обладающих растворимостью вблизи изоэлектрической точки, в технологии напитков. Представляет интерес повышение эффективности ферментативного гидролиза сывороточных белков за счет фракционирования гидролизатов молочной сыворотки с использованием ультрафильтрации. Как следствие продукты фракционирования, а именно пермеат с низкомолекулярными пептидными фракциями, прогнозируемо являются потенциальными ингредиентами в технологии напитков. Практический интерес представляет производство термостойких напитков, содержащих высокий уровень сывороточных белков. The article summarizes the latest theoretical approaches to the regulation of thermal reactions of denaturation and aggregation of whey proteins, including physical, chemical, enzymatic, as well as combinations of various methods. Describes the behavior of modified whey proteins during heat treatment. Among the methods of physical modification, the existing technologies for processing whey proteins using ultrasound, as well as processing proteins under high pressure in combination with preheating are given. The review emphasizes that any chemical modification of whey proteins is carried out by disrupting the protein structure by blocking free sulfhydryl groups. Methods for increasing thermal stability are presented, such as the creation of protein-polysaccharide complexes that exhibit the characteristics of pseudoplastic fluids at a pH close to the isoelectric point. The review notes the ability of the glycation reaction to also increase the thermal stability of whey proteins. The prospects for enzymatic modification of whey proteins in the food industry are emphasized, which contribute to an increase in both thermal stability and solubility of proteins at acidic pH values due to the loss of secondary structure. The possibility of using hydrolysis products with a solubility close to the isoelectric point in the technology of beverage production is noted. It is of interest to increase the efficiency of enzymatic hydrolysis of whey proteins due to fractionation of whey hydrolysates using ultrafiltration. Fractionation products, namely permeate with low molecular weight peptide fractions, are predictable potential ingredients in beverage technology. Of practical interest is the production of heat-resistant drinks with a high content of whey proteins.

Experimental Investigations on the Effect of Mixing Procedures on the Rheological Properties of Oilwell Cement Slurries

Well cementing is an essential operation in the oil and gas industry, and it is a key material to ensure wellbore integrity through the life of the well. Improper cement design can trigger well construction risks such as de-bonding and leakage pathways near-wellbore and through the annulus. Mixing non-newtonian fluids is one of the most challenging tasks, especially for pseudoplastic fluids exhibiting yield stress, such as wellbore cement slurry. Mixing conditions for cement slurries and their effect on rheological properties and thickening time has been debated through the literature. In this study, based on laboratory-scale experiments, we provide testing results for rheological properties and thickening time by changing mixing conditions. Our results show that slurries mixed under similar mixing energy do not necessarily result in similar rheological properties. Comparing rheological measurements from lower mixing energy to higher mixing energy, plastic viscosity decreases; however, yield point increases. This implies the dual opposite effect of mixing time on rheological properties. This may have severe implications for field operations where mixing must be improved to enable successful cement operation.

Using tomography, CFD, and dynamic tests to study the continuous-flow mixing of yield-pseudoplastic fluids

The major technological challenges faced by modern chemical industries are non-ideal flows such as dead zones and channeling encountered in the mixing of fluids with complex rheology. These cause sub-optimal mixing and lead to low quality products and high costs of raw materials. Therefore, the core objectives of this study were to develop methodology and tools to design an efficient continuous-flow mixing system for the fluids with complex rheology using electrical resistance tomography (ERT), computational fluid dynamics (CFD), and dynamic tests. The xanthan gum solution, which is a pesudoplastic fluid with yield stress, was used to study the dynamic behavior of the continuous-flow mixing process. The power consumption, cavern size, mixing time, and the extents of channelling and the fraction of fully mixed volume were successfully determined using dynamic tests, ERT tests, and CFD simulations and used as mixing quality criteria. A novel and efficient method was developed for flow visualization in the continuous-flow mixing of opaque fluids using 2D and 3D tomograms. A unique study on identifying the sources of flow non-ideality in non-Newtonian fluids with yield stress was done by visualizing the flow pattern inside the continuous-flow mixing vessel using 2D and 3D tomograms. The deformation of the cavern was analyzed and quantified in the continuous-flow mixing system for yield-pseudoplastic fluids using ERT. Moreover, the cavern volume was compared with the fully mixed volume and it was found that the latter was higher due to the extra momentum induced by the inlet-outlet flow. A novel study on exploring the effect of the rheological parameters of the pseudoplastic fluids with yield stress on the non ideal flows in a continuous-flow mixing system was performed using CFD. The CFD results revealed that the mixing quality was improved when the degree of the shear thinning was increased. The ratio of the residence time to the batch mixing time was evaluated to achieve ideal mixing for the continuous-flow mixing of yield-pseudoplastic fluids using dynamic tests and ERT. It was found that the ratio of residence time to the batch mixing time should be at least 8.2 or higher to achieve ideal mixing.

Mixing of complex fluids with coaxial mixers composed of two central impellers and an anchor

The coaxial mixers composed of a high-speed central impeller and a low-speed anchor have been recommended by the previous researchers for the mixing of highly viscous and non-Newtonian fluids. However, no study has been reported in the literature regarding the use of the coaxial mixing systems composed of two central impellers and an anchor in the agitation of complex fluids. Thus, the main objective of this study was to investigate the performance of coaxial mixers composed of two central impellers and an anchor in the agitation of the xanthan gum solution, which is a yield-pseudoplastic fluid, through electrical resistance tomography (ERT), the computational fluid dynamics (CFD), and design of experiments (DOE) combined with the response surface methodology (RSM). In the first stage of this study, the hydrodynamic performance of coaxial mixers, the single and double Scaba impellers in combination with an anchor impeller, was investigated in the mixing of yield-pseudoplastic fluids. Considering the mixing efficiency criteria, it was found that the double Scaba-anchor coaxial system was more efficient than the single Scaba-anchor coaxial mixer in the mixing of yield pseudoplastic fluids with regard to the mixing time and power drawn. In the second stage of this research project, the performances of three different coaxial mixers, namely, double Scaba-anchor coaxial (DSAC), double Rushton turbine-anchor coaxial (DRAC), and double pitched blade turbine-anchor coaxial (DPAC) mixers were assessed. It was found that the double Scaba-anchor coaxial (DSAC) mixer was more efficient system compared to the others at the same operating conditions. To evaluate the influence of the impeller spacing on the hydrodynamics of the double Scaba-anchor coaxial mixer, the lower impeller clearance and the spacing between two central impellers were changed within a wide range. The results demonstrated that a coaxial mixer with the impeller spacing of almost equal to the central impeller diameter was the most efficient configuration compared to the other cases. When the impeller spacing was varied, the merging flow and parallel flow patterns were observed. Finally, the hydrodynamic performances of different configurations of coaxial mixers composed of a wall scraping anchor impeller in combination with two different or identical central high-speed impellers were analyzed. The coaxial mixers utilized in this stage were the Scaba–Scaba-anchor (SSAC), Scaba-Rushton-anchor (SRAC), Rushton-Scaba-anchor (RSAC), Scaba-pitched blade-anchor (SPBAC), and pitched blade-Scaba-anchor (PBSAC). A new correlation was introduced for these complex configurations of the coaxial mixers by incorporating the Metzner-Otto constants (Ks) of the different types of the central impellers into the Reynolds number. The analysis of the collected data revealed that the Scaba-pitched blade-anchor coaxial (SPBAC) mixer was the most efficient mixing system in the mixing of the highly viscous non-Newtonian fluids.

Mixing of complex fluids with coaxial mixers composed of two central impellers and an anchor

The coaxial mixers composed of a high-speed central impeller and a low-speed anchor have been recommended by the previous researchers for the mixing of highly viscous and non-Newtonian fluids. However, no study has been reported in the literature regarding the use of the coaxial mixing systems composed of two central impellers and an anchor in the agitation of complex fluids. Thus, the main objective of this study was to investigate the performance of coaxial mixers composed of two central impellers and an anchor in the agitation of the xanthan gum solution, which is a yield-pseudoplastic fluid, through electrical resistance tomography (ERT), the computational fluid dynamics (CFD), and design of experiments (DOE) combined with the response surface methodology (RSM). In the first stage of this study, the hydrodynamic performance of coaxial mixers, the single and double Scaba impellers in combination with an anchor impeller, was investigated in the mixing of yield-pseudoplastic fluids. Considering the mixing efficiency criteria, it was found that the double Scaba-anchor coaxial system was more efficient than the single Scaba-anchor coaxial mixer in the mixing of yield pseudoplastic fluids with regard to the mixing time and power drawn. In the second stage of this research project, the performances of three different coaxial mixers, namely, double Scaba-anchor coaxial (DSAC), double Rushton turbine-anchor coaxial (DRAC), and double pitched blade turbine-anchor coaxial (DPAC) mixers were assessed. It was found that the double Scaba-anchor coaxial (DSAC) mixer was more efficient system compared to the others at the same operating conditions. To evaluate the influence of the impeller spacing on the hydrodynamics of the double Scaba-anchor coaxial mixer, the lower impeller clearance and the spacing between two central impellers were changed within a wide range. The results demonstrated that a coaxial mixer with the impeller spacing of almost equal to the central impeller diameter was the most efficient configuration compared to the other cases. When the impeller spacing was varied, the merging flow and parallel flow patterns were observed. Finally, the hydrodynamic performances of different configurations of coaxial mixers composed of a wall scraping anchor impeller in combination with two different or identical central high-speed impellers were analyzed. The coaxial mixers utilized in this stage were the Scaba–Scaba-anchor (SSAC), Scaba-Rushton-anchor (SRAC), Rushton-Scaba-anchor (RSAC), Scaba-pitched blade-anchor (SPBAC), and pitched blade-Scaba-anchor (PBSAC). A new correlation was introduced for these complex configurations of the coaxial mixers by incorporating the Metzner-Otto constants (Ks) of the different types of the central impellers into the Reynolds number. The analysis of the collected data revealed that the Scaba-pitched blade-anchor coaxial (SPBAC) mixer was the most efficient mixing system in the mixing of the highly viscous non-Newtonian fluids.

Using tomography, CFD, and dynamic tests to study the continuous-flow mixing of yield-pseudoplastic fluids

The major technological challenges faced by modern chemical industries are non-ideal flows such as dead zones and channeling encountered in the mixing of fluids with complex rheology. These cause sub-optimal mixing and lead to low quality products and high costs of raw materials. Therefore, the core objectives of this study were to develop methodology and tools to design an efficient continuous-flow mixing system for the fluids with complex rheology using electrical resistance tomography (ERT), computational fluid dynamics (CFD), and dynamic tests. The xanthan gum solution, which is a pesudoplastic fluid with yield stress, was used to study the dynamic behavior of the continuous-flow mixing process. The power consumption, cavern size, mixing time, and the extents of channelling and the fraction of fully mixed volume were successfully determined using dynamic tests, ERT tests, and CFD simulations and used as mixing quality criteria. A novel and efficient method was developed for flow visualization in the continuous-flow mixing of opaque fluids using 2D and 3D tomograms. A unique study on identifying the sources of flow non-ideality in non-Newtonian fluids with yield stress was done by visualizing the flow pattern inside the continuous-flow mixing vessel using 2D and 3D tomograms. The deformation of the cavern was analyzed and quantified in the continuous-flow mixing system for yield-pseudoplastic fluids using ERT. Moreover, the cavern volume was compared with the fully mixed volume and it was found that the latter was higher due to the extra momentum induced by the inlet-outlet flow. A novel study on exploring the effect of the rheological parameters of the pseudoplastic fluids with yield stress on the non ideal flows in a continuous-flow mixing system was performed using CFD. The CFD results revealed that the mixing quality was improved when the degree of the shear thinning was increased. The ratio of the residence time to the batch mixing time was evaluated to achieve ideal mixing for the continuous-flow mixing of yield-pseudoplastic fluids using dynamic tests and ERT. It was found that the ratio of residence time to the batch mixing time should be at least 8.2 or higher to achieve ideal mixing.