PROBLEM TO BE SOLVED: To make it possible to carry out the solubilization having suitability for living bodies or the extraction by means of forming reversed micelle by using a surfactant arising from organisms and natural oils and fats or their derivatives.
SOLUTION: The surfactant originating from organisms [phospholipid surfactants, e.g. raw soybean lecithin or a mixture of soybean phosphatidylcholine (1 mole) and a fatty acid (0.4-4 moles of oleic acid) is added into natural oils and fats or their derivatives (fatty acid ethyl esters, e.g. ethyl oleate and ethyl linolate) used as the oil phase to form a reversed micelle. By incorporating slightly oil-soluble or oil-insoluble substances (e.g. protein and the like) into the water pull in this reversed micelle or the interface of reversed micelle, the solubilization capable of using in fields relating to foods and medicines or the extraction is carried out.