Production of Emulsions in High‐Pressure Homogenizers – Part I: Disruption and Stabilization of Droplets

Abstract

In continuous mechanical emulsification, disruption and stabilization of droplets determine the resulting droplet size and, thus, the emulsion's microstructure. Without the need of adding any stabilizer, w/o emulsions provide the possibility of a high viscosity of the continuous phase and, in consequence, of decreasing the probability of coalescence. The present work presents investigations on the production of w/o emulsions in high-pressure homogenizers: the different geometries of standard valve, microfluidizer and orifice valve are compared to each other with reference to disruption and stabilization of droplets. In the orifice valve, droplets are disrupted most efficiently; however, coalescence superimposes the disruption result to a higher extent than in the microfluidizer. On the basis of simulations of the flow pattern, the geometry of the orifice valve has been improved: the new conical valve provides for higher volumetric flow rates and a lower extent of coalescence in comparison to the orifice valve.

Efficiency of a range of homogenisation technologies in the emulsification and stabilization of cream liqueurs

“…These droplets are very difficult to deform and thus need high kinetic turbulent energy in order to be disrupted. Droplet disruption in an orifice nozzle homogeniser is predominately due to deformation by laminar elongational flow before and within the nozzle, followed by turbulence at the nozzle outlet (Stang et al, 2001;Tesch et al, 2003). For the model cream liqueur under study, it appears that droplet disruption due to laminar elongational flow in an orifice nozzle homogeniser was not efficient, signifying the impact of the thick membrane of the milk fat globules, preventing their deformation.…”

“…The geometry of the homogenising nozzle appears to be a very important factor influencing droplet disruption (Stang et al, 2001;Tesch, Freudig, & Schubert, 2003).…”

Optical Measuring Methods for the Investigation of High-Pressure Homogenisation

“…Thus, the influence of different parameters like pressure drop [2][3][4][5], geometry of the device [2,6-9], or formulation [10][11][12][13] can be related to homogenisation efficiency, which allows some mechanistic insight into the high-pressure homogenisation process. However, offline measurements always represent an integral result of superimposed effects and do not display…”

Energiesparende Homogenisierung von Milch mit etablierten sowie neuartigen Verfahren

“…Die deformierten Filamente werden in der sich anschließenden turbulenten und kavitierenden Strömung im Auslaufbereich der Blende aufgebrochen [2,12,13]. Eine Ursache dafür sind die Störungen der Strömung am Umschlagpunkt zwischen laminarer und turbulenter Strömung [14,15], die auch eine Folge von Kavitationserscheinungen sein können [16,17]. Insbesondere für höhere Viskositätsverhält-nisse von disperser zu kontinuierlicher Phase ist die Dehnströmung überaus vorteilhaft, um feine Tropfen bei möglichst geringem Energieeintrag herstellen zu können [2, 18 -22].…”