Natural oil bodies from typical oilseeds: Structural characterization and their potentials as natural delivery system for curcumin

Natural oil body (OB), due to the fascinating surface membrane structure, has a great potential to be a typical natural delivery system. In this work, three kinds of OBs with different components and surface membrane structure were extracted from rapeseed, camellia and flaxseed, respectively. Their compositions and structural characteristics had been fully characterized by SDS-PAGE, low field nuclear magnetic resonance (NMR), the cryo-Scanning Electron Microscope etc. Furthermore, curcumin as bioactive compound was loaded into these OBs via pH-shift method. The impact of structural and membrane constructional differences between three kinds of OBs on both encapsulation and gastrointestinal digestion fate of curcumin were also investigated. The rapeseed OB had the highest surface membrane protein content and lowest particle size (0.77 μm), leading to a relative higher encapsulation efficiency (91.87%) and bioaccessibility (91.3%) of curcumin and the highest release of FFAs (18.19 μmol ml −1), while camellia OB the lowest. The stubborn flaxseed gum on flaxseed OB protected the surface membrane proteins from hydrolysis, which contribute to the highest bioaccessibility of curcumin (94.32%). The different surface membrane structure of the three kinds of OBs, especially the protein content, affected the loading process of curcumin and their digestion in gastrointestinal tract. The results of rheology also showed that OBs with high protein content might be more effective in encapsulation of bioactive molecules, coupled with a negative influence on the stability of interfacial layers. These results may contribute to the application of natural OBs from oilseeds in multiple food processing including plant-based milk, fortified food and so on.