Hypothesis: Nanocellulose (NC) has been a topic of significant interest due to its multiple applications, including that as a potential food ingredient. Due to the viscous property of NC and its potential use as emulsion stabilizers, presence of NC in food may affect properties and digestion of lipid emulsions systems. In this study, the behavior of three types of nanocellulose and its influence on lipid emulsions during digestion were investigated. Experiments: The changes in physicochemical characteristics (including particle size, microstructure, viscosity, and zeta potential) of the emulsions as well as the amount of free fatty acid released were studied and compared among the addition of different types concentrations of fiber as well as digestion phases. Findings: The colloidal stability of three types of NC differed during each digestion phase. Specifically, cellulose nanocrystals (CNC) formed hydrogel networks during the gastric phase, resulting in increased digesta viscosity. Cellulose nano-fibrils (CNF) were stable and had no morphological changes during digestion. TEMPO-oxidized cellulose nano-fibrils (TEMPO-CNF) de-swelled and showed aggregation at the gastric phase. Results showed that all three types of nanocellulose at high concentrations (1% CNF, 0.25-0.36% TEMPO-CNF or 2-3% CNC) delayed initial in vitro digestion of emulsions, though the final lipolysis extent was nearly the same amongst all (47-55%). (C) 2019 Elsevier Inc. All rights reserved.