title: Preparation of a water-in-oil-in-water (W/O/W) type microcapsules by a single-droplet-drying method and change in encapsulation efficiency of a hydrophilic substance during storage.
abstract: Microcapsules of a water-in-oil-in-water (W/O/W) emulsion, which contained a hydrophilic substance, 1,3,6,8-pyrenetetrasulfonic acid tetrasodium salt (PTSA), in its inner aqueous phase, was prepared by hot-air-drying or freeze-drying the emulsion using a single-droplet-drying method. Pullulan, maltodextrin, or gum arabic was used as a wall material, and the oily phase was tricaprylin, oleic acid, olive oil, or a mixture of tricaprylin and olive oil. An encapsulation efficiency higher than 0.95 was reached except for the microcapsules prepared using gum arabic and oleic acid. The hot-air-dried microcapsules were generally more stable than the freeze-dried microcapsules at 37 degrees C and various relative humidities. The stability was higher for the microcapsules with tricaprylin as the oily phase than for the microcapsules with oleic acid. The higher stability of the microcapsules with tricaprylin would be ascribed to the lower partition coefficient of PTSA to the oily phase. There was a tendency for the stability to be higher at lower relative humidity for both the hot-air- and freeze-dried microcapsules. The volumetric fraction of olive oil in its mixture with tricaprylin did not significantly affect either the encapsulation efficiency or the stability of the hot-air-dried microcapsules.
authors.affiliation: Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan. adachi@kais.kyoto-u.ac.jp
authors.forename: Shuji
authors.initials: S
authors.lastname: Adachi
authors.forename: Hanaho
authors.initials: H
authors.lastname: Imaoka
authors.forename: Yuri
authors.initials: Y
authors.lastname: Hasegawa
authors.forename: Ryuichi
authors.initials: R
authors.lastname: Matsuno
mesh_terms: D002210:Caprylates; D002214:Capsules / Q000138:chemical synthesis* / Q000592:standards; D004339:Drug Compounding / Q000379:methods* / Q000592:standards; D004356:Drug Storage / Q000379:methods* / Q000592:standards; D004655:Emulsions / Q000737:chemistry*; D008722:Methods; D009821:Oils; D000069463:Olive Oil; D010938:Plant Oils; D011134:Polysaccharides; D011721:Pyrenes; D055672:Static Electricity; D014280:Triglycerides; D014867:Water
chemical_list: D002210:Caprylates; D002214:Capsules; D004655:Emulsions; D009821:Oils; D000069463:Olive Oil; D010938:Plant Oils; D011134:Polysaccharides; D011721:Pyrenes; D014280:Triglycerides; D014867:Water; C003637:tricaprylin; C041343:1,3,6,8-pyrene tetrasulfonate