Pectic polysaccharides with different structural characteristics as inhibitors of pancreatic lipase

The effect of molecular weight (MW) and methoxylation degree (MD) of apple (A) and citrus (C1-C5) pectic polysaccharides (PPs) on both the digestion of emulsified lipids and the pancreatic lipase activity was evaluated by using a static in vitro digestion system and a simplified system, respectively. The first system consisted in the simulated digestion [composed of an initial (before digestion), oral, gastric, and intestinal phases] of a soybean oil-in-water emulsion containing PPs at initial concentrations of 0 (control) and 0.1% (w/w) of PPs with pancreatic lipase. The microstructure and particle size distribution of the soybean oil-in-water emulsions were characterized before (initial phase) and after (intestinal phase) the in vitro digestion process. During the intestinal phase the free fatty acid released were measured as well. The second system consisted of an acidic (H2SO4) back titration of Tris-HCl buffer after the hydrolysis of triacetin with pancreatic lipase, in the presence of PPs at concentrations of 0 (control) and 0.01% (w/v). Among tested PPs A [MW, 209 kDa; and MD, 73.3% (mol/mol)] was the most effective one in inhibiting the activity of pancreatic lipase in both the static in vitro digestion model (63% activity as compared to the control) and the simplified model (61% activity as compared to the control). From the contour plot, after mathematical modelling, MD of PPs had a greater influence as compared to MW on the inhibition of the activity of pancreatic lipase, with higher inhibition of enzymatic activity as the MD was increased.