Impact of Emulsifier Structure and Concentration on Lipolysis Dynamics and Curcumin Bioaccessibility in the Nanoemulsions Stabilized by Polyglycerol Fatty Acid Esters

Polyglycerol fatty acid esters (PGFEs), a type of nonionic surfactants, have been widely used in food industry. However, the effects of the aliphatic chain lengths in PGFEs and the concentrations of PGFEs on digestive profiles in emulsion-based systems are poorly understood. The present study has investigated the physicochemical stability, lipolysis dynamics and curcumin bioaccessibility in the nanoemulsions stabilized by synthesized PGFEs with different aliphatic chains (C10-C18) at various concentrations using an in vitro gastrointestinal tract (GIT) model. Shorter aliphatic chain or higher concentrations of PGFEs resulted in smaller droplets in the emulsions before and during digestion. PGFEs concentration had different impacts on lipolysis dynamics of nanoemulsions depending on the aliphatic chain lengths of PGFEs. Furthermore, long aliphatic chain of PGFEs contributed to a greater rate and extent of lipolysis, but a lower bioaccessibility of curcumin compared with medium ones, which was attributed to the formation of insoluble calcium soaps induced by calcium ions. These results are expected to facilitate the application of PGFEs for developing optimized nanoemulsions in encapsulating poorly water-soluble nutraceuticals in functional food industry.