Influence of Ginkgo biloba extracts and of their flavonoid glycosides fraction on the in vitro digestibility of emulsion systems

The objective of this study was to investigate the influence of Ginkgo biloba extracts (GBE) and of their flavonoid glycosides fraction (FA) on the in vitro digestibility of emulsion systems. A soybean oil-in-water emulsion (10 wt% oil) was prepared using GBE or FA particles as emulsifiers. We showed that the droplet size distribution in the FA and GBE particle-stabilized emulsions was monomodal with mean droplet sizes of 0.8 and 1.0 μm, respectively. Moreover, after storage, the emulsions were relatively more stable against coalescence than Tween 20-stabilized emulsions. Our emulsions were also compared to conventional Tween 20 (0.1 wt%)-stabilized emulsions in terms of their lipid digestion kinetics by using an in vitro digestion model at pH 7.0 and pH 8.9. At both pH conditions, lipolysis in the FA- or GBE-stabilized emulsions was appreciably slower, and the total concentration of released fatty acids was much lower than in Tween 20-stabilized emulsions. The flavonoids adsorbed at the oil-water interface could barely be displaced by Tween 20, even at high concentrations (0.3 wt%), suggesting that the slower lipolysis observed in FA- or GBE-stabilized emulsions could be a result of the strong and irreversible adsorption of FA and GBE particles at the emulsion oil droplets. Furthermore, the bioaccessibility of flavonoids in FA-stabilized emulsions (39%) was considerably higher than in GBE-stabilized emulsions (11%).