Nanocellulose (NC) has become a topic of increasing interest due to its potential applications and special characteristics, including its rheological and structural properties (specifically viscous property and large specific surface area). The objective of this research was to investigate the influence of three types of nanocellulose (nano-fibrillated cellulose (also called cellulose nanofibrils (CNF)), TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical) oxidized CNF (TEMPO-CNF) & nano-crystalline cellulose (also called cellulose nanocrystals (CNC))) on food digestion and nutrient absorption as well as its behavior during gastrointestinal digestion using a simulated static in vitro digestion model. It was found that all three types of nanocellulose exerted hypoglycemic potential, delayed lipid digestion and free amino nitrogen (FAN) absorption at high NC concentrations. The viscosity was observed to play a major role in the effects of all three types of NC on food (starch, lipid and protein) digestion and nutrient absorption. Specifically, the addition of higher concentrations of NC (corresponding to higher viscosity) resulted in lower initial digestion rates, even though the final amount of digestion products released were almost the same with 4% (w/w) CNC as an exception (which resulted in significantly lower amounts of FAN released). Nanocellulose at higher concentrations (0.5~1% (w/w) CNF, 0.36% (w/w) TEMPO-CNF and 2~4% (w/w) CNC) was found to significantly retard nutrient absorption, especially glucose and FAN diffusion. Furthermore, compared to cellulose, CNF had higher glucose and cholesterol adsorption capacity as well as bile acid retardation effects. Interactions can also occur between NC and food products. TEMPO-CNF and CNC bound with whey protein isolate (WPI) at the initial and gastric phase, resulted in changes in mean particle size and viscosity. Three types of NC showed different behaviors during digestion. In particular, CNF and cellulose were morphologically stable during the digestion, while TEMPO-CNF became aggregated and CNC formed hydrogels at the gastric phase. This study indicates that all three types of nanocellulose are advantageous than cellulose in the gastrointestinal (GI) tract in terms of increasing digesta viscosity, delaying food digestion and nutrient absorption, and has potential to be used in the development of functional foods to control nutrient absorption and promote satiety.
