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7. Formation by high power ultrasound of aggregated emulsions stabilised with milk protein concentrate (MPC70)

Author

Zhang, R, Luo, L, Yang, Z, Ashokkumar, M, Hemar, Y, Zhang, R, Luo, L, Yang, Z, Ashokkumar, M, and Hemar, Y

Abstract

In this work, oil-in-water emulsions stabilised by milk protein concentrate (MPC70) were investigated. The MPC70 concentration was kept constant at 5% (close to the protein content found in skim milk) and the oil volume fraction was varied from 20 to 65%. Sonication was performed at 20 kHz and at a constant power of 14.4 W for a total emulsion volume of 10 mL. Under certain oil concentration (≥35%) and sonication times (≥3s) the emulsion aggregated and formed high-viscosity pseudo plastic materials. However, the viscosity behaviour of the emulsion made with 35% oil reverted to that of a liquid if sonicated for longer times (≥15 s). Confocal laser scanning microscopy showed clearly that the oil droplets are aggregated under the sonication conditions and oil concentrations indicated above. An attempt to explain this behaviour through a simple model based on the bridging of oil droplets by the MPC70 particles and, taking into account the oil droplet and MPC70 particle sizes as well as the oil volume fraction, was made. The model fails to describe in details the aggregation behaviour of these emulsions, likely due to the inhomogeneous protein layer, where both free caseins and casein micelles are adsorbed, and to the packing of the oil droplets at concentrations ≤55%. Nonetheless, this work demonstrates the potential of ultrasound processing for the formation of dairy emulsions with tailored textures.

Published
2021

19. Characterization of flow and mixing regimes within the ileum of the brushtail possum using residence time distribution analysis with simultaneous spatio-temporal mapping

Author

Janssen, P W M, Lentle, R G, Asvarujanon, P, Chambers, P, Stafford, K J, and Hemar, Y

Subjects
Time Factors, Muscle, Smooth, Opossums, In Vitro Techniques, Galactans, Mannans, Solutions, Kinetics, Ileum, Alimentary, Oscillometry, Calibration, Plant Gums, Animals, Gastrointestinal Motility
Abstract

We studied the flow and mixing regimes in isolated segments of the terminal ileum of brushtail possums during spontaneous circumferential and longitudinal contractions under conditions that allowed backflow and compared them with those of inactive segments. Residence time distributions (RTDs) were determined by perfusion with two probes of different rheological properties to which an inert dye marker was added. Ileal segment volume and oscillatory flow during the period of RTD determination were derived from spatiotemporal maps. High viscosity guar gum solution generated RTDs characteristic of laminar flow in inactive ileal segments which confirmed that no slip was occurring at the mucosal layer. In active segments, motility and consequent oscillatory flow imparted significant additional axial dispersion to the flow patterns of both probes. Mixing occurred episodically during periods when intestinal volume was reduced and onflow was augmented by peristalsis, which may prevent the establishment of steady state conditions. Marker concentration rose more steeply when active ileal segments were being perfused with a probe of similar viscosity to normal digesta than with low viscosity Earle's/Hepes solution, each being subject to similar levels of oscillatory flow. This indicated that a coarser mixing regime prevailed and that absorption of nutrients from viscous digesta would rely to a greater degree on molecular diffusion.

Published
2007

20. Heat-induced flocculation of microparticulated whey proteins (MWP); consequences for mixed gels made of MWP and beta-lactoglobulin

Author

Renard, Denis, Lavenant, Laurence, Hemar, Y., Horne, D., Sanchez, Christian, PhysicoChimie des Macromolécules (LPCM), Institut National de la Recherche Agronomique (INRA), Laboratoire de Physico-chimie et Génie Alimentaires, and Institut National Polytechnique de Lorraine (INPL)

Subjects
[CHIM.OTHE]Chemical Sciences/Other, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2002

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