title: Preparation and characterization of water/oil/water emulsions stabilized by polyglycerol polyricinoleate and whey protein isolate.
abstract: In this study we tried to prepare stable water-in-oil-in-water (W/O/W) emulsions using polyglycerol polyricinoleate (PGPR) as a hydrophobic emulsifier and whey protein isolate (WPI) as a hydrophilic emulsifier. At first, water-in-oil (W/O) emulsions was prepared, and then 40 wt% of this W/O emulsion was homogenized with 60 wt% aqueous solution of different WPI contents (2, 4, and 6 wt% WPI) using a high-pressure homogenizer (14 and 22 MPa) to produce W/O/W emulsions. The mean size of final W/O/W droplets ranged from 3.3 to 9.9 microm in diameter depending on the concentrations of PGPR and WPI. It was shown that most of the W/O/W droplets were small (<5 microm) in size but a small population of large oil droplets (d > 20 microm) was also occasionally observed. W/O/W emulsions prepared at the homogenization pressure of 22 MPa had a larger mean droplet size than that prepared at 14 MPa, and showed a microstructure consisting of mainly approximately 6 to 7-microm droplets. When a water-soluble dye PTSA as a model ingredient was loaded in the inner water phase, all W/O/W emulsions showed a high encapsulation efficiency of the dye (>90%) in the inner water phase. Even after 2 wk of storage, >90% of the encapsulated dye still remained in the inner water phase; however, severe droplet aggregation was observed at relatively high PGPR and WPI concentrations.
authors.affiliation: Center for Agricultural Biomaterials and Dept. of Biosystems and Biomaterials Science and Engineering, Seoul Natl. Univ., Seoul 151-742, Korea.
authors.forename: Saehun
authors.initials: S
authors.lastname: Mun
authors.forename: Yongdoo
authors.initials: Y
authors.lastname: Choi
authors.forename: Shin-Joung
authors.initials: SJ
authors.lastname: Rho
authors.forename: Choon-Gil
authors.initials: CG
authors.lastname: Kang
authors.forename: Chan-Ho
authors.initials: CH
authors.lastname: Park
authors.forename: Yong-Ro
authors.initials: YR
authors.lastname: Kim
mesh_terms: D002368:Castor Oil / Q000737:chemistry*; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D004655:Emulsions / Q000737:chemistry*; D005990:Glycerol / Q000031:analogs & derivatives* / Q000737:chemistry; D008894:Milk Proteins / Q000737:chemistry*; D012277:Ricinoleic Acids / Q000737:chemistry*; D014867:Water / Q000737:chemistry*; D000067816:Whey Proteins
chemical_list: D004655:Emulsions; D008894:Milk Proteins; D012277:Ricinoleic Acids; D000067816:Whey Proteins; C029243:glyceran polyricinoleic acid ester; D014867:Water; D002368:Castor Oil; D005990:Glycerol