Controlling in vitro lipid digestion: Pickering emulsions with cellulose nanocrystals, chitosan and methylcellulose

Engineering foods has become a focus of research to tailor lipid digestion and improve health outcomes. We report the use of cellulose nanocrystals (CNCs) combined with either methylcellulose (MC) or chitosan (Ch) to stabilise Pickering emulsions, varying composition, order of mixing and fabrication method to improve emulsion stability and slow down lipolysis. Emulsion properties were characterised by laser diffraction, zeta-potential and fluorescence microscopy. Lipolysis was monitored using the pH-stat method, mimicking the intestinal phase, followed by a standardised gastrointestinal model (INFOGEST) to simulate oral, gastric and duodenal phases. Incorporation of MC or Ch led to an increase in droplet size, and improved stability in simulated digestive fluids. MC and Ch significantly reduced lipolysis (p < 0.05), with a free fatty acid (FFA) release after the 3-stage digestion of 73 % (CNC), 64 % (CNC/MC), 70 % or 56 % (CNC/Ch, with Ch added sequentially or first complexed to CNC as particles). Emulsions stabilised by CNC and Ch that were complexed together, rather than added sequentially, led to the largest reduction in FFA. All emulsions produced showed no cytotoxicity under experimental conditions. Together, these results demonstrate the potential of CNCs combined with dietary fibre as nanomaterials in food products to modulate the rate of lipid digestion.