Fabrication and in vitro digestion behavior of Pickering emulsions stabilized by chitosan-caseinophosphopeptides nanocomplexes

Abstract

The nanocomplexes assembled from chitosan (CS) and caseinophosphopeptides (CPPs) were utilized to stabilize Pickering emulsions with medium-chain triglyceride (MCT) as the oil phase. The CS-CPPs nanocomplexes composed of CS:CPPs = 1:1, 2:1, 4:1 were prepared and their physical properties including particle size, contact angle, and surface tension were characterized. The concentration ranges of these nanocomplexes that can stabilize Picking emulsion decreased in the following sequence, CS:CPPs = 1:1 (C1P1) > 2:1 (C2P1) > 4:1 (C4P1). The fraction of oil that can be stabilized by these three kinds of nanocomplexes at 0.15 wt% concentration was similar, and increasing the concentration of nanocomplexes can stabilize a higher fraction of MCT. The fluorescence microscopy image indicated that the Pickering emulsions were oil-in-water type emulsions. These emulsions were stable against ionic strength (0–0.3 M NaCl) changes after 24 h storage but low pH (pH 2) could affect their stabilities. These CS-CPPs nanocomplexes stabilized Pickering emulsions showed gel-like behavior. In vitro lipolysis studies revealed that coverage of the CS-CPPs nanocomplexes at the oil-water interface could reduce the rate and extent of MCT digestion, manifesting that they may potentially be used as fat replacers in foods to reduce oil absorption.