Impact of a food-grade cationic biopolymer (ε-polylysine) on the digestion of emulsified lipids: In vitro study

ε-Polylysine (ε-PL) is a cationic biopolymer that may be used as a food ingredient because of its strong antimicrobial activity and potential to inhibit pancreatic lipase. We examined the effect of polylysine on the digestion of corn oil-in-water emulsions stabilized by either a natural anionic surfactant (quillaja saponin) or a synthetic non-ionic surfactant (Tween 20). Emulsions were prepared using high pressure homogenization (microfluidization) and then subjected to in vitro digestion in the absence or presence of polylysine at the maximum level allowed in foods by the FDA. Samples were characterized before and after in vitro digestion using electrophoresis, confocal microscopy, and static light scattering. The presence of polylysine decreased the hydrolytic activity of pancreatic lipase by around 53% and 28% in the Tween 20- and saponin-stabilized emulsions, respectively. The lipase-inhibiting properties of cationic polylysine were attributed to its electrostatic interaction with anionic components, such as bile salts, free fatty acids, and digestive enzymes. These results have important implications for the incorporation of polylysine into food systems, particularly those containing lipophilic nutrients. •The impact of polylysine on lipid digestion was studied using an in vitro model.•Polylysine inhibited lipid digestion, possibly by binding to anionic species.•Polylysine may therefore interfere with the absorption of lipophilic bioactives.•The impact of polylysine was greater for Tween 20 than for Q-Naturale.