The interfacial destabilization of bile salt-emulsified oil droplets, essential for lipase function, is mediated by Lycium barbarum L. leaf polysaccharides

A bile salt (BS)-stabilized water/oil interface is a prerequisite for the pancreas lipase (PL) mediated hydrolyzation of triacylglycerol. Previous fat digestion research mainly focused on direct lipase inhibition by bioactive substances while ignoring the destructive role of these substances on BS-stabilized lipid emulsions. Here, we showed that polysaccharides (LP) weakly suppressed PL but destroyed BS-stabilized emulsions and thus inhibited free fatty acid (FFA) release. Physicochemical analysis showed that LP actions toward emulsion stability were mainly due to endogenous minerals (28%) in LP which affected aggregation and amphiphilic properties of BSpolysaccharide composites. This was evidenced by high wettability and low interfacial tension in demineralized polysaccharide and BS composites, with three phase contact angles which were identified as 80.4 degrees and 95.6 degrees as well as interfacial tensions as 9.26 and 9.37 mN/m, respectively. However, the low wettability, which was detected as 76.2 degrees and 78.6 degrees as well as high interfacial tension as 10.77 and 11.02 mN/m, respectively, was only observed in mineral-containing polysaccharides and BS composites. Further investigations showed that interactions with mineral-containing polysaccharides occupied hydrophobic sites in BS thereby elevating composite hydrophilicity. These findings provided novel insights into the effects of plant-sourced polysaccharides on fat digestion from an interface chemistry perspective, and in particular, they deepened our understanding of polysaccharide interactions with intestine-secreted lipid digestants.

Automated summary

A stable water/oil interface stabilized by bile salts is essential for the hydrolysis of triacylglycerol by pancreatic lipase. Polysaccharides weakly inhibit the activity of pancreatic lipase, but they also disrupt the stability of bile salt-stabilized emulsions, resulting in the inhibition of free fatty acid release. These findings provide insights into the interface chemistry of polysaccharides in fat digestion and enhance our understanding of their interactions with lipid digestants.