Controlled structuring of dispersed multiphase food systems

Abstract

The dispersed systems, such as emulsions and suspensions, are encountered in a large variety of applications areas, such as food, cosmetics, pharmaceutics and polymers. In order to obtain the desired properties of an emulsion in the dispersing process, the droplet size distribution has to be monitored and controlled. By combining droplet generation, deformation and fixation (emulsion-suspension transition) in one experimental set-up, equally shaped particles were produced in order to manipulate the microstructure of dispersions. In a first step, a co-flowing liquid-liquid emulsification process aiming to generate monodispersed droplets^[1–2] was studied. With such droplets at hand, deformation of each individual droplet can be achieved in the second step when the flow field of the downstream apparatus is known. Using gelling biopolymeric material as dispersed phase it is further possible to “freeze” and conserve the non-equilibrium shapes of such deformed droplet. As a consequence, suspensions of gelled emulsion droplets of various shape and shape functionality were obtained^[3–5]. These new shapes, such as sphere, fibrils and “hooky” bodies, provide an advanced tool to control and manipulate the rheological properties and product performance of dispersed systems beside the well-known influence of the volume fraction of the dispersed particles^{[4, 6–8]}.

Keywords

emulsions / suspensions / biopolymers / gelation / co-flow emulsification

References

[1] CramerC., FischerP., WindhabE. J.. Liquid jet stability in a laminar flow field[J]. Chemical Engineering and Technology, 2002, 25: 499-505

[2] CramerC., FischerP., WindhabE. J.. Drop formation in a co-flowing ambient fluid[J]. Chemical Engineering Science, 2004, 59: 3045-3058

[3] WaltherB., WalkenströmP., HermanssonA. M., et al.. Flow processing and gel formation: A promising combination for the design of the shape gelatin drops[J]. Food Hydrocolloids, 2002, 16: 633-643

[4] WaltherB., HambergL., WalkenströmP., et al.. Formation of shaped drops in a fast continuous flow process[J]. Journal of Colloid Interface Science, 2004, 270: 195-204

[5] HambergL., WohlwendM., WalkenströmP., et al.. Shapes and shaping of biopolymer drops in a hyperbolic flow[J]. Food Hydrocolloids, 2003, 17: 641-652

[6] WALTHER B, CRAMER C, TIEMEYER A, et al. Drop deformation dynamics and gel kinetics in a co-flowing water-in-oil system[J]. Journal of Colloid and Interface Science,.2005, 278.

[7] MARTI I, HÖFLER O, FISCHER P, et al. Rheology of concentrated suspensions containing mixtures of spheres and fibres[J]. Rheologica Acta, 4xx, 2005.

[8] WolfB., FrithW. J., SingletonS., et al.. Shear behaviour of biopolymer suspensions with spheroidal and cylindrical particles[J]. Rheologica Acta, 2001, 40: 238-247

[9] BibetteJ., Leal-calderonF., SchmittV., et al.Emulsion Science[M], 2002, Berlin, Springer

[10] YuyamaH., YamamotoK., ShirafujiK., et al.. Preparation of polyurethaneurea uniforme spheres by SPG membrane emulsification technique[J]. Journal of Applied Polymer Science, 2000, 77: 2237-2245

[11] SugiuraS., NakajimaM., SekiM.. Prediction of droplet diameter for microchannel emulsification[J]. Langmuir, 2002, 18: 3854-3859

[12] BasaranO. A.. Small scale free surface flows with breakup: Dropl formation and emerging applications[J]. AIChE Journal, 2002, 28: 1842-1848

[13] CRAMER C. Continuous Drop Formation at a Capillary Tip and Drop Deformation in a Flow Channel[M]. Zurich/Switzerland: ETH Dissertation 15460, 2004.

[14] UmbanhowarP. B., PrasadV., WeitzD. A.. Monodispersed emulsion generation via drop break off in a coflowing stream[J]. Langmuir, 2000, 16: 347-351

[15] Megías-AlguacilD., FischerP., WindhabE. J.. Experimental determination of interfacial tension by different dynamical methods under simple shear flow conditions with a novel computer-controlled parallel band apparatus[J]. Journal of Colloid and Interface Science, 2004, 274: 631-636