Impact of surfactants on the lipase digestibility of gum arabic-stabilized O/W emulsions

• The effect of the low-molecule weight surfactants on the physical properties and lipase digestibility is evaluated.
• Low-molecule weight surfactants show different adsorptive behavior on the droplets interface coated with gum arabic.
• The lipolysis behavior is influenced by surfactant type and concentration.
• A combination of a digestion model in vitro with interfacial techniques is used.

The bioavailability of lipids from an emulsion can be controlled and regulated by the property of the stabilizing interfacial layer. Here we evaluate how low-molecular weight surfactants including hexadecyl trimethyl ammonium bromide (CTAB), sodium dodecyl sulfate (SDS), and Tween 80 (T80) influence the interfacial behavior of lipase and bile extract on the surface of lipid droplets stabilized with gum arabic (GA). The lipolysis behavior was influenced by surfactant type and concentration. The results showed that anionic SDS could completely displace GA from droplet surface. Cationic CTAB might either adsorb onto existing GA layers or displace GA, whereas non-ionic T80 could co-adsorb with GA on the interface. When the concentration of surfactants was much higher than the critical micelle concentration (CMC), all the surfactants would form a dense adsorption layer on the droplet interface to prevent lipase from the direct contact with lipids. A considerable amount of surfactant in the aqueous phase may also compete with the bile salt and lipase, thus leading to suppressed digestion of lipids. Ionic surfactants would denature the lipase resulting in reduced enzyme activity, and T80 micelles may interact with the lipase, hindering their adsorption onto the droplet interface as well. These results were confirmed both by the digestion model and interfacial techniques. The results provided guidance for the development of emulsion-based delivery systems for functional lipid foods.

Effect of surfactant type and concentration on digestion rate of 10 wt.% GA stabilized emulsions during in vitro digestion by lipase. T80 exhibited the slow and fast digestion rates in the lag period. Figure optionsDownload as PowerPoint slide