Preparation of a curcumin oil bodies delivery system based on pH-Shift treatment: Physicochemical properties, protein structure, and digestive properties

Curcumin (Cur) was encapsulated in oil bodies (OBs) using pH-shift treatment. The physicochemical properties, surface protein structure, stability, and in vitro digestion of the prepared composite emulsion (COB) were characterized. The results showed a fading of Cur crystallization peak in COB. Besides, the highest encapsulation rate, largest particle size and zeta potential were observed at pH 0.5. Compared to OBs, the hydrophilic groups of COB surface proteins were unfolded and the central hydrophobic region remained relatively stable, with reduced COB storage stability and good oxidative stability. In vitro simulated digestion revealed that Cur was released in a sustained manner. The highest bioaccessibility (57.5%) and stability (67.3%) of COB were observed at pH 0.5. The present study suggested that pH-shift treatment is a viable method for the preparation of COB carriers. This information may provide new ideas for the preparation of lipophilic polyphenol delivery systems such as Cur, which can contribute to the application of OBs in a variety of food processing applications, including plant-based milk, fortified foods, etc.