title: Pickering emulsions stabilized by whey protein nanoparticles prepared by thermal cross-linking.
abstract: A Pickering (o/w) emulsion was formed and stabilized by whey protein isolate nanoparticles (WPI NPs). Those WPI NPs were prepared by thermal cross-linking of denatured WPI proteins within w/o emulsion droplets at 80°C for 15 min. During heating of w/o emulsions containing 10% (w/v) WPI proteins in the water phase, the emulsions displayed turbid-transparent-turbid phase transitions, which is ascribed to the change in the size of the protein-containing water droplets caused by thermal cross-linking between denatured protein molecules. The transparent stage indicated the formation of WPI NPs. WPI NPs of different sizes were obtained by varying the mixing speed. WPI NPs of 200-500 nm were selected to prepare o/w Pickering emulsions because of their good stability against coalescence. By Confocal Laser Scanning Microscopy, it was observed that WPI NPs were closely packed and distributed at the surface of the emulsion droplets. By measuring water contact angles of WPI NPs films, it was found that under most conditions WPI NPs present good partial wetting properties, but that at the isoelectric point (pI) and high ionic strength the particles become more hydrophobic, resulting in less stable Pickering emulsion. Thus, at pH above and below the pI of WPI NPs and low to moderate ionic strengths (1-10 mM), and with a WPI NPs concentration of 2% (w/v), a stable Pickering emulsion can be obtained. The results may provide useful information for applications of WPI NPs in environmentally friendly and food grade applications, notably in food, pharmaceutical and cosmetic products.
authors: State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, College of Life Science and Technology, P.O. Box 53, 100029 Beijing, China.
authors: Jiande
authors: J
authors: Wu
authors: State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, College of Life Science and Technology, P.O. Box 53, 100029 Beijing, China.
authors: Mengxuan
authors: M
authors: Shi
authors: State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, College of Life Science and Technology, P.O. Box 53, 100029 Beijing, China.
authors: Wei
authors: W
authors: Li
authors: State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, College of Life Science and Technology, P.O. Box 53, 100029 Beijing, China.
authors: Luhai
authors: L
authors: Zhao
authors: State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, College of Life Science and Technology, P.O. Box 53, 100029 Beijing, China.
authors: Ze
authors: Z
authors: Wang
authors: State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, College of Life Science and Technology, P.O. Box 53, 100029 Beijing, China.
authors: Xinzhong
authors: X
authors: Yan
authors: State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, College of Life Science and Technology, P.O. Box 53, 100029 Beijing, China; Laboratory of Physical Chemistry and Colloid Science, Wageningen University, Dreijenplein 6, 6703 HB Wageningen, The Netherlands.
authors: Willem
authors: W
authors: Norde
authors: State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, College of Life Science and Technology, P.O. Box 53, 100029 Beijing, China. Electronic address: liyuan@mail.buct.edu.cn.
authors: Yuan
authors: Y
authors: Li
mesh_terms: D003432:Cross-Linking Reagents / Q000737:chemistry*; D004655:Emulsions / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D018613:Microscopy, Confocal; D053758:Nanoparticles / Q000737:chemistry*; D009821:Oils / Q000737:chemistry; D009994:Osmolar Concentration; D055672:Static Electricity; D013696:Temperature; D014867:Water / Q000737:chemistry; D017155:Wettability; D000067816:Whey Proteins / Q000737:chemistry*
chemical_list: D003432:Cross-Linking Reagents; D004655:Emulsions; D009821:Oils; D000067816:Whey Proteins; D014867:Water
keywords: Heat-resistant protein particles; Pickering emulsions; Thermal cross-linking; Whey protein nanoparticle