A simulated in vitro digestion model was used to elucidate the impact of dietary fibers on the digestion rate of emulsified lipids. The influence of polysaccharide type (chitosan (cationic), methyl cellulose (non-ionic), and pectin (anionic)) and initial concentration (0.4 to 3.6% (w/w)) was examined. 2% (w/w) corn oil-in-water emulsions stabilized by 0.2% (w/w) Tween-80 were prepared, mixed with polysaccharide, and then subjected to an in vitro digestion model (37 °C): initial (pH 7.0); oral (pH 6.8; 10 min); gastric (pH 2.5; 120 min); and, intestinal (pH 7.0; 120 min) phases. The impact of polysaccharides on lipid digestion, ζ-potential, particle size, viscosity, and stability was determined. The rate and extent of lipid digestion decreased with increasing pectin, methyl cellulose, and chitosan concentrations. The free fatty acids released after 120 min of lipase digestion were 46, 63, and 81% (w/w) for methyl cellulose, pectin, and chitosan, respectively (3.6% (w/w) initial polysaccharide), indicating that methyl cellulose had the highest capacity to inhibit lipid digestion, followed by pectin, and then chitosan. The impact of the polysaccharides on lipid digestion was attributed to their ability to induce droplet flocculation, and/or due to their interactions with molecular species involved in lipid hydrolysis, such as bile salts, fatty acids, and calcium. These results have important implications for understanding the influence of dietary fibers on lipid digestion. The control of lipid digestibility within the gastrointestinal tract might be important for the development of reduced-calorie emulsion-based functional food products.

Protein nanoparticles are often not very stable in a complex food matrix because they are primarily stabilized by electrostatic repulsion. In this study, we envisaged the stabilization of zein nanoparticles through Maillard conjugation reactions with polysaccharides of different molecular mass. Zein nanoparticles (0.5% w/v) containing resveratrol (0.025% w/v grape skin extract) were produced by liquid antisolvent precipitation and coated with Maillard conjugates (MC) of sodium caseinate and different molecular mass carbohydrates during particle production. Zein nanoparticles coated with conjugated polysaccharides of 2.8, 37, and 150 kDa had diameters of 198 ± 5, 176 ± 6, and 180 ± 3 nm, respectively. The encapsulation efficiency (∼83%) was not affected by conjugation, but the conjugates significantly improved particle stability against changes in pH (2.0-9.0), CaCl2 addition (up to 100 mM), and heat treatment (30-90 °C, 30 min). Zein nanoparticles coated by MC may therefore be suitable delivery systems for hydrophobic bioactive molecules in a wide range of commercial products.

a b s t r a c tMedium methoxylated pectin (52% mol/mol, MMP) was isolated from banana passion fruit (Passiflora tripartita var. mollisima) by hot acidic extraction. The impact of MMP on lipid digestion was compared to that of commercial citrus pectins with high (71% mol/mol, HMP) and low (30% mol/mol, LMP) methoxylation degree. A static in vitro digestion model was used to elucidate the impact of pectin properties (methoxylation degree and molecular weight) on the gastrointestinal fate of emulsified lipids. A 2.0% (w/ w) corn oil-in-water emulsion stabilized with 0.2% (w/w) Tween 80 was prepared, mixed with 1.8% (w/w) pectin samples, and then subjected to the static in vitro digestion model (37 C): initial (pH 7.0); oral (pH 6.8, 10 min, mucin); gastric (pH 2.5, 120 min, pepsin); and intestinal (pH 7.0, 120 min, bile salts, and pancreatic lipase) phases. The impact of the three pectin samples on surface particle charge (z-potential), particle size distribution of lipid droplets, microstructure, rheology, and lipid digestion (free fatty acids (FFAs) released) was determined. The rate and extent of lipid digestion decreased with increasing simultaneously both the molecular weight and pectin methoxylation, with the FFAs released after 120 min of intestinal digestion being 47, 70, and 91% (w/w) for HMP, MMP, and LMP, respectively. These results have important implications for understanding the influence of pectin on lipid digestion. The control of lipid digestibility within the gastrointestinal tract might be important for the designing and development of novel functional foods to control bioactive release or to modulate satiety.