Structural and interfacial characterization of oil bodies extracted from Camellia oleifera under the neutral and alkaline condition

Camellia oleifera seed oil contains nearly 80% oleic acid, which accounts for health-benefits, and it is stored in the subcellular oil bodies (OBs) organelles. To utilize C. oleifera OBs as a dietary supplement of unsaturated fatty acid, the physical properties need to be investigated. The physical stabilities of extracted OBs against ionic strength (0.01–1M) and temperature (30–90 °C) were evaluated via Turbiscan analysis and confocal microscope. The results showed that OBs extracted at alkaline conditions (pH 9.0–11) exhibited uniform dispersion. The surface charge of the OBs decreased dramatically with increasing NaCl content, and OBs droplet aggregation occurred under a NaCl concentration of 0.1 mol/L. Moreover, high temperature (up to 90 °C) had a positive effect on OBs stability. Overall, OBs extracted under alkaline pH were more stable than those extracted under neutral pH. Differences in the interfacial proteins of OBs extracted at the neutral and alkaline pHs were studied via sodium dodecyl sulfate-acrylamide gel electrophoresis (SDS-PAGE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). Six types of oleosins, including Ole Ⅲ, the fragment of Ole Ⅱ, oleosin, Ole Ⅳ, Ole Ⅴ, and Ole Ⅰ, were found in the extracted membrane proteins. Oleosins and some coextracted endogenous proteins played a certain role in OBs stability. • Alkaline condition was favorable for extracting of oil bodies' interfacial proteins. • Turbiscan monitored the stability of oil bodies against ionic strength and heating. • Interfacial proteins for stabilizing oil bodies were identified by LC-MS/MS. • Oleosin, OleⅢ, OleⅡ, OleⅣ, OleⅤ, and OleⅠ were the main oil bodies' interfacial proteins.