Food dispersions are commonly created and stabilized by the addition of hydrophobic surfactants. Optimal use of these hydrophobic surfactants requires knowledge of the mechanistic basis of adsorption. Lecithin, a complex mixture of long chain phospholipids, is a commonly used hydrophobic surfactant in the food industry. When lecithin is dispersed in excess water, a liquid crystal phase is formed that may be dispersed as vesicles with enough energy. Such vesicle dispersions are used in many practical situations to deliver lipid to a surface or interface and modify the interfacial characteristics, yet little is known about the delivery mechanism. The stability and physiochemical properties of the food system may be able to be adequately controlled through processing conditions if the controlling adsorption mechanisms are known. We investigated the adsorption dynamics of commercially available sunflower lecithin to an air-water interface from a dispersion of small unilamellar vesicles with mean diameters of 130nm. Adsorption kinetics were tracked using dynamic surface tension measurements obtained by drop profile tensiometry at room temperature for a variety of lecithin concentrations. This particular sunflower lecithin is comprised of &gt;90wt% phosphatidylcholine, less than 5wt% of lysophosphatidylcholine (LPC), and a small amount of water and triglycerides. The adsorption behavior of sunflower lecithin was compared that of a mixed system of dilauroylphosphatidycholine with or without 5wt% LPC to determine the role of LPC in the adsorption process. The effect of convection strength on the surface tension dynamics was also examined. The success of this work could lead to the development of more robust processing conditions in several areas, including the stabilization of foams and emulsions, particle formulation in spray drying, modification of wetting agents and lubricants, and the design of drug delivery enhancers.

Adsorption behavior of sunflower lecithin at an air-water interface: Role of lysolecithin

255th National Meeting (2018)

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