Impact of Layer Structure on Physical Stability and Lipase Digestibility of Lipid Droplets Coated by Biopolymer Nanolaminated Coatings

The objective of this study was to investigate the influence of the structure of nanolaminated biopolymer coatings surrounding lipid droplets on their physical stability and in vitro digestibility by pancreatic lipase. Caseinate (Ca) was used as an amphoteric emulsifier, pectin (P) was used as an anionic polyelectrolyte, and chitosan (C) was used as a cationic polyelectrolyte. The electrostatic layer-by-layer deposition approach was used to prepare multilayer emulsions containing lipid droplets coated by: (1) the same coating composition but different layer order (Ca–P–C and Ca–C–P); (2) the same outer layer but different coating compositions (e.g., Ca–P, Ca–P–C–P, and Ca–C–P). The stability of the emulsions to pH changes (3 to 7) depended strongly on the order of biopolymers within the nanolaminated coatings and on the nature of the outer coating. The lipid droplets in all of the multilayer emulsions were largely digested by lipase within 30 min when monitored using an in vitro digestion model (pH-Stat). This information could be useful for the rational design of delivery systems for lipophilic bioactive compounds that need to be encapsulated within foods but released in the human body.