title: Interfacial behaviour of biopolymer multilayers: Influence of in vitro digestive conditions.
abstract: Although multilayered emulsions have been related to reduced lipolysis, the involved interfacial phenomena have never been studied directly. In this work, we systematically built multilayers of whey protein and pectin, which we further subjected to digestive conditions, using two different techniques: droplet volume tensiometry to investigate interfacial rheology, and reflectometry to determine the amount of adsorbed material. Interfacial tension and dilatational rheology were linked to adsorption/desorption kinetics measured under static in vitro conditions. The interfacial tension and rheology of the multilayers was rather similar to those found for single whey protein layers, as well as their resistance to duodenal conditions and lipolytic components, which is explained by the rapid destabilisation of multilayers at neutral pH. Sequential adsorption of bile extract or lipase to pre-adsorbed films rapidly lowered the interfacial tension via co-adsorption and displacement, forming a viscoelastic film with low mechanical strength, and highly dynamic adsorption/desorption. When both were present, bile salts dominated the initial adsorption, followed by lipase co-adsorption and formation of lipolysis products that further lowered the interfacial tension, forming a complex interface (including biopolymers, bile salts, lipase, and lipolysis products), independent of pre-adsorbed biopolymer layers. Our study shows that the combination of drop volume tensiometry and reflectometry can be used to study complex interfacial behaviours under digestive conditions, which can lead to smart design of interfacial structures for controlled lipolysis in food emulsions.
authors.affiliation: Wageningen University, Department of Agrotechnology & Food Sciences, Food Process Engineering Group, Wageningen, The Netherlands. Electronic address: meinou.corstens@wur.nl.
authors.forename: Meinou N
authors.initials: MN
authors.lastname: Corstens
authors.affiliation: Wageningen University, Department of Agrotechnology & Food Sciences, Food Process Engineering Group, Wageningen, The Netherlands. Electronic address: liliaosoriocaltenco@gmail.com.
authors.forename: Lilia A
authors.initials: LA
authors.lastname: Osorio Caltenco
authors.affiliation: Wageningen University, Department of Agrotechnology & Food Sciences, Physical Chemistry and Colloid Science Group, Wageningen, The Netherlands. Electronic address: renko.devries@wur.nl.
authors.forename: Renko
authors.initials: R
authors.lastname: de Vries
authors.affiliation: Wageningen University, Department of Agrotechnology & Food Sciences, Food Process Engineering Group, Wageningen, The Netherlands. Electronic address: karin.schroen@wur.nl.
authors.forename: Karin
authors.initials: K
authors.lastname: Schroën
authors.affiliation: Wageningen University, Department of Agrotechnology & Food Sciences, Food Process Engineering Group, Wageningen, The Netherlands. Electronic address: claire.carabin-berton@wur.nl.
authors.forename: Claire C
authors.initials: CC
authors.lastname: Berton-Carabin
mesh_terms: D000327:Adsorption; D001647:Bile Acids and Salts / Q000378:metabolism*; D001704:Biopolymers / Q000737:chemistry / Q000378:metabolism*; D004063:Digestion; D006801:Humans; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007700:Kinetics; D008049:Lipase / Q000378:metabolism*; D008066:Lipolysis; D010316:Particle Size; D012212:Rheology; D013499:Surface Properties
chemical_list: D001647:Bile Acids and Salts; D001704:Biopolymers; D008049:Lipase
keywords: Droplet volume tensiometry; Duodenal conditions; Interfacial rheology; Layer-by-layer; Oil–water interface; Reflectometry