title: Controlling Agglomeration of Protein Aggregates for Structure Formation in Liquid Oil: A Sticky Business.
abstract: Proteins are known to be effective building blocks when it comes to structure formation in aqueous environments. Recently, we have shown that submicron colloidal protein particles can also be used to provide structure to liquid oil and form so-called oleogels ( de Vries , A. J. Colloid Interface Sci. 2017 , 486 , 75 - 83 ) . To prevent particle agglomeration, a solvent exchange procedure was used to transfer the aggregates from water to the oil phase. The aim of the current paper was to elucidate on the enhanced stability against agglomeration of heat-set whey protein isolate (WPI) aggregates to develop an alternative for the solvent exchange procedure. Protein aggregates were transferred from water to several solvents differing in polarity to investigate the effect on agglomeration and changes in protein composition. We show that after drying protein aggregates by evaporation from solvents with a low polarity (e.g., hexane), the protein powder shows good dispersibility in liquid oil compared to powders dried from solvents with a high polarity. This difference in dispersibility could not be related to changes in protein composition or conformation but was instead related to the reduction of attractive capillary forces between the protein aggregates during drying. Following another route, agglomeration was also prevented by applying high freezing rates prior to freeze-drying. The rheological properties of the oleogels prepared with such freeze-dried protein aggregates were shown to be similar to that of oleogels prepared using a solvent exchange procedure. This Research Article provides valuable insights in how to tune the drying process to control protein agglomeration to allow for subsequent structure formation of proteins in liquid oil.
authors.affiliation: Top Institute Food and Nutrition , Nieuwe Kanaal 9A, 6709 PA Wageningen, The Netherlands.|Laboratory of Physics and Physical Chemistry of Foods, Wageningen University , P.O. Box 17, 6700 AA Wageningen, The Netherlands.
authors.forename: Auke
authors.identifier: http://orcid.org/0000-0001-7293-2884
authors.initials: A
authors.lastname: de Vries
authors.affiliation: Laboratory of Physics and Physical Chemistry of Foods, Wageningen University , P.O. Box 17, 6700 AA Wageningen, The Netherlands.
authors.forename: Yuly
authors.initials: Y
authors.lastname: Lopez Gomez
authors.affiliation: Laboratory of Physics and Physical Chemistry of Foods, Wageningen University , P.O. Box 17, 6700 AA Wageningen, The Netherlands.
authors.forename: Bas
authors.initials: B
authors.lastname: Jansen
authors.affiliation: Laboratory of Physics and Physical Chemistry of Foods, Wageningen University , P.O. Box 17, 6700 AA Wageningen, The Netherlands.
authors.forename: Erik
authors.initials: E
authors.lastname: van der Linden
authors.affiliation: Top Institute Food and Nutrition , Nieuwe Kanaal 9A, 6709 PA Wageningen, The Netherlands.|Laboratory of Physics and Physical Chemistry of Foods, Wageningen University , P.O. Box 17, 6700 AA Wageningen, The Netherlands.
authors.forename: Elke
authors.initials: E
authors.lastname: Scholten
mesh_terms: D005612:Freeze Drying; D009821:Oils; D010316:Particle Size; D011208:Powders; D066329:Protein Aggregates; D012997:Solvents
chemical_list: D009821:Oils; D011208:Powders; D066329:Protein Aggregates; D012997:Solvents
keywords: agglomeration; oleogels; protein aggregates; structure