« Pratique de la communication », de J. Aimeras, P. Noblecourt, J. Chastrusse

Villette J.M. « Pratique de la communication », de J. Aimeras, P. Noblecourt, J. Chastrusse. In: Communication et langages, n°44, 4ème trimestre 1979. p. 121

« Pratique de la communication », de J. Aimeras, P. Noblecourt, J. Chastrusse

Villette J.M. « Pratique de la communication », de J. Aimeras, P. Noblecourt, J. Chastrusse. In: Communication et langages, n°44, 4ème trimestre 1979. p. 121

« Les objectifs pédagogiques », de D. Hameline

Villette J.M. « Les objectifs pédagogiques », de D. Hameline. In: Communication et langages, n°44, 4ème trimestre 1979. p. 122

« Les objectifs pédagogiques », de D. Hameline

Villette J.M. « Les objectifs pédagogiques », de D. Hameline. In: Communication et langages, n°44, 4ème trimestre 1979. p. 122

Dynamic emulsification and catastrophic phase inversion of lecithin based emulsions

International audienceIn emulsification phase inversion is induced by several parameters like temperature, salt concentration, fraction of oil or water and energy input. In this work phase inversion of a sunflower oil–lecithin–water emulsion system was induced by the variation of water volume fraction (fw), called as catastrophic inversion, in a laboratory scale mixing tank. For this purpose two sets of dynamic emulsification were performed: (i) fw was decreased (0.5–0.1) and (ii) fw was increased (0.1–0.7). Hysteresis in phase inversion under dynamic condition was observed compared to direct emulsification and the degree of hysteresis seemed to depend on how the fw was varied, i.e. 0.5–0.1 or 0.1–0.7. However, inversion point depended on salt concentration which was used as one of the formulation parameters to place an emulsion on formulation-composition map (HLD versus fw). Such map with the phase equilibrium behavior and colloidal interactions seems to be useful to explain the mechanism of catastrophic phase inversion under dynamic conditions. This study showed also that the dynamic emulsification lead to incorporate higher fraction of the dispersed phase (more than 82% volume) which is not possible with the direct emulsification. Moreover dynamic emulsification can be a useful protocol to prepare stable emulsions with smaller droplets

Spectrophotometric method associated with formulation scans for application of hydrophilic–lipophilic deviation concept in food emulsions

International audienceHydrophilic–lipophilic deviation (HLD) concept is well developed in the fields of cosmetics, pharmaceutics and enhanced oil recovery and therefore, it is adopted for emulsification process in a predictive and controlled way. To apply this concept, it is necessary to get the knowledge of optimum formulation (i.e. emulsion’s environmental parameters at which the affinity of emulsifier for aqueous and oil phase is equal) through formulation scans. In above fields optimum formulation of the oil–water–emulsifier system is commonly detected through simple techniques like visual observation, light scattering, and interfacial tension measurements. Unfortunately, such techniques are not suitable for food emulsion systems, because of the complexities associated with the emulsifiers and vegetable oils. This study deals with the detection of optimum formulation (formulation scan with respect to salt concentration) of food grade emulsion system through spectrophotometric assay of emulsifier molecule in the aqueous and oil phase, and in microemulsion. It is shown that the spectrophotometric method associated with formulation scans is a relatively more accurate method to detect optimum formulation. This method was studied with a model system which resembles to a mayonnaise, i.e. sunflower oil–water–lecithin. Spectrophotometric method associated with formulation scans put forward a better understanding of transitional inversion which is pre-requisite to make a formulation–composition map of an emulsion system