Connecting the Drops : Observing Collective Flow Behavior in Emulsions
Dijksman, Joshua A. - \ 2019
Frontiers in Physics 7 (2019). - ISSN 2296-424X
anisotropy - emulsion - friction - non-local - surfactants - yield stress fluids
Thoroughly mixing immiscible fluids creates droplets of one phase dispersed in a continuum of the other phase. In such emulsions, the individual droplets have rather mundane mechanical behavior. However, densely confining these suspended droplets generates a packing of particles with a spectacular diversity of mechanical behavior whose origins we are only beginning to understand. This mini review serves to survey a non-exhaustive range of experimental dense slow flow emulsion work. To embed these works in the context of the flow behavior of other structured fluids, we also discuss briefly the related non-local flow modeling attempts as one of the approaches that has been used successfully in describing emulsion flow properties and other materials.
Comparison of the functional properties of RuBisCO protein isolate extracted from sugar beet leaves with commercial whey protein and soy protein isolates
Martin, Anneke H. ; Castellani, Oscar ; Jong, Govardus A.H. de; Bovetto, Lionel ; Schmitt, Christophe - \ 2019
Journal of the Science of Food and Agriculture 99 (2019)4. - ISSN 0022-5142 - p. 1568 - 1576.
emulsion - gel - green leaf protein - solubility - sugar beet
Background: RuBisCO was extracted from sugar beet leaves using soft and food-compatible technologies. Proximate composition, solubility, emulsifying, foaming and gelling properties of the protein isolate were determined. All these properties were systematically benchmarked against commercial whey and soy protein isolates used in food applications. Results: RuBisCO protein isolate (RPI) contained 930 g kg−1 of crude protein. Protein solubility was higher than 80% at pH values lower than 4.0 or higher than 5.5. Foaming capacity of RPI was better at pH 4.0 than at pH 7.0. Interestingly, 10 g kg−1 protein foams were more stable (pH 7.0 and 4.0) than foams obtained with whey or soy protein. Moreover, 10 g kg−1 RPI emulsions at pH 4.0 or 7.0 exhibited good stability, being similar to whey protein isolate. Remarkable gelling properties were observed at pH 7.0, where 50 g kg−1 protein solutions of RPI formed self-supporting gels while more concentrated solutions were needed for whey or soy protein. Conclusion: RuBisCO showed comparable or superior functional properties to those of currently used whey and soy protein isolates. These results highlight the high potential of sugar beet leaf protein isolate as a nutritious and functional food ingredient to face global food security and protein supply.
Food-grade Micro-encapsulation Systems that May Induce Satiety via Delayed Lipolysis: A Review
Corstens, M.N. ; Berton-Carabin, C.C. ; Vries, R.J. de; Troost, F.J. ; Masclee, A.A.M. ; Schroen, C.G.P.H. - \ 2017
Critical Reviews in Food Science and Nutrition 57 (2017)10. - ISSN 1040-8398 - p. 2218 - 2244.
In vitro digestion - Ileal brake - emulsion - Food - obesity
The increasing prevalence of overweight and obesity requires new, effective prevention and treatment strategies. One approach to reduce energy intake is by developing novel foods with increased satiating properties, which may be accomplished by slowing down lipolysis to deliver substrates to the ileum, thereby enhancing natural gut-brain signalling pathways of satiety that are normally induced by meal intake. To develop slow release food additives, their processing in the gastrointestinal tract has to be understood; therefore, we start from a general description of the digestive system and relate that to in vitro modelling, satiety and lipolytic mechanisms. The effects of physicochemical lipid composition, encapsulation matrix and interfacial structure on lipolysis are emphasized. We give an overview of techniques and materials used, and discuss partitioning, which may be a key factor for encapsulation performance. Targeted release capsules that delay lipolysis form a real challenge because of the high efficiency of the digestive system; hardly any proof was found that intact orally ingested lipids can be released in the ileum and thereby induce satiety. We expect that this challenge could be tackled with structured o/w-emulsion-based systems that have some protection against lipase, e.g., by hindering bile salt adsorption and/or delaying lipase diffusion.
Cross-flow microfluidic emulsification from a food perspective
Muijlwijk, K. ; Berton-Carabin, C.C. ; Schroen, C.G.P.H. - \ 2016
Trends in Food Science and Technology 49 (2016). - ISSN 0924-2244 - p. 51 - 63.
Microfluidics - cross-flow - emulsification - food - emulsion
Background: The use of microfluidics is a relatively new route to produce emulsions. Advantages of this method include high energy efficiency, high droplet monodispersity, and potential use for the production of high added-value and fragile products. However, the current productivity is still rather low compared to what would be needed in an industrial setting.
Scope and Approach: In this review we discuss the mechanisms of emulsion droplet formation in crossflow microfluidics, and how microfluidic design, shear forces and interfacial tension forces influence droplet formation. These combined insights will be used to discuss the potential of cross-flow microfluidics for the production of food emulsions.
Key Findings and Conclusions: In order to make emulsions at large scale, the current devices need to be parallelised even more than shown in the successful examples known from literature. Besides, the behaviour of ingredients used in emulsion formulation need to be tested in greater detail; e.g. the effect
of interfacial tension is captured in scaling relations, but dynamic interfacial tension behaviour not. For this also microfluidic analytical tools have been suggested, and the first positive results were obtained. As soon as these two requirements are met, microfluidics become a promising option for the production of (high added-value) emulsion food products.
Watching paint dry: more exciting than it seems
Kooij, H.M. van der; Sprakel, J.H.B. - \ 2015
Soft Matter 11 (2015)32. - ISSN 1744-683X - p. 6353 - 6359.
latex film formation - thin liquid-films - colloidal dispersions - polymer diffusion - particle-size - cracking - coalescence - emulsion - water - deformation
With an ever-increasing demand for sustainable alternatives to solvent-borne coatings and paints, the pressure to develop aqueous alternatives that match or exceed the performance of their traditional counterparts rises. A crucial step in this sustainability challenge for the years to come is to arrive at a deep, and complete, understanding of how aqueous paints dry and form their final protective films. As it turns out, this is no minor challenge. Yet, understanding drying and film formation is a prototypical soft matter problem at heart, displaying a rich variety of complex non-equilibrium phenomena that are waiting to be understood. Watching paint dry is far from the boring activity the saying suggests.
Influence of dispersed particles on small and large deformation properties of concentrated caseinate composites
Manski, J.M. ; Kretzers, I.M.J. ; Brenk, S. van; Goot, A.J. van der; Boom, R.M. - \ 2007
Food Hydrocolloids 21 (2007)1. - ISSN 0268-005X - p. 73 - 84.
filled gelatin gels - rheological properties - viscoelastic properties - mechanical-properties - molecular dimensions - matrix interaction - size distribution - food - emulsion - suspensions
Concentrated sodium caseinate composites (30% w/w in water), which contained either dispersed palm fat or glass spheres varying in size and surface properties were prepared in a Brabender Do-Corder kneader. The influence of the dispersed phase on the structural properties of the sodium caseinate composites was investigated using both small oscillating and large tensile deformations. Both experimental results and selected models showed that all measured properties were mainly influenced by the volume fraction of the dispersed particles. The type of filler, particle size and surface properties showed no differences in the small deformation properties, whereas the matrix-filler interaction played an important role in the large deformation properties. From the latter followed that sodium caseinate exhibited amphiphilic properties. Selected theoretical relations with the maximum volume packing fraction and the matrix-filler interaction as important parameters, agreed well with the experimental results. The relatively simple models can be applied as guidelines for designing composite food products.
Diffuse interface model of surfactant adsorption onto flat and droplet interfaces
Sman, R.G.M. van der; Graaf, S. van der - \ 2006
Rheologica Acta 46 (2006)1. - ISSN 0035-4511 - p. 3 - 11.
simple shear-flow - of-fluid method - membrane emulsification - lattice-boltzmann - phase-separation - dynamics - simulation - breakup - tension - emulsion
For applications where droplet breakup and surfactant adsorption are strongly coupled, a diffuse interface model is developed. The model is based on a free energy functional, partly adapted from the sharp interface model of [Diamant and Andelman 34(8):575-580, (1996)]. The model is implemented as a 2D Lattice Boltzmann scheme, similar to existing microemulsion models, which are coupled to hydrodynamics. Contrary to these microemulsion models, we can describe realistic adsorption isotherms, such as the Langmuir isotherm. From the free energy, functional analytical expressions of equilibrium properties are derived, which compare reasonably with numerical results. Interfacial tension lowering scales with the logarithm of the area fraction of the interface unloaded with a surfactant:, Delta sigma similar to ln(1 - psi(0)). Furthermore, we show that adsorption kinetics are close to the classical relations of Ward and Tordai. Prelimary simulations of droplets in shear flow show promising results, with surfactants migrating to interfacial regions with highest curvature. We conclude that our diffuse interface model is very promising for apprehending the above-mentioned applications as membrane emulsification.
Influence of membrane morphology on pore activation in membrane emulsification
Gijsbertsen-Abrahamse, A.J. ; Padt, A. van der; Boom, R.M. - \ 2003
Journal of Membrane Science 217 (2003)1-2. - ISSN 0376-7388 - p. 141 - 150.
microfiltration membranes - flow - emulsion - droplets - glass
The low throughput of the disperse phase is one of the issues in cross-flow membrane emulsification. This is apparent in the low percentage of pores at which droplets are formed (few active pores). To determine the effect of membrane morphology on pore activation, we developed and experimentally validated a model that describes the flow phenomena in and under a membrane with uniform pores (microsieve). In this model the membrane is divided into two parts: the toplayer and the membrane substructure. The model was validated with a larger-scale physical analogon. It predicts a linear increase of the number of active pores with increasing transmembrane pressure, while the pressure difference over the active pores is independent of the transmembrane pressure as long as not all pores are active. Although the resistance of the microsieve substructure was found to be four times lower than the resistance of a single pore, the resistance of the membrane substructure had a large effect on the activation of pores. Hence, the number of active pores can be increased by increasing the ratio of flow resistance in the pores and the flow resistance in the membrane substructure. Preliminary experiments show that the gradual increase in active pores at a ceramic membrane surface can be explained in the same way. (C) 2003 Elsevier Science B.V. All rights reserved.