Simultaneous extraction of oil and tea saponin from Camellia oleifera Abel. seeds under subcritical water conditions

Camellia oleifera Abel. (Camellia oleifera) seeds oil and tea saponin were simultaneously extracted under subcritical water extraction (SWE) conditions. A response surface methodology (RSM) was used for optimizing the SWE process by varying independent variables temperature (×1: 110–150 °C), extraction time (×2: 20–40 min) and solvent to material ratios (×3: 5:1–15:1 mL/g). The highest extraction yield of oil is 94.07% at the condition of 133.59 °C, 32.03 min, 10.79 mL/g with the tea saponin yield 71.38%, and the highest extraction yield of tea saponin is 74.21% with the oil yield 91.27% of the total content at the condition of 121.11 °C, 32.07 min, 8.33 mL/g. Analytical results showed that extracted oil has a similar fatty acid profile and quality as those of the cold Soxhlet extraction(SE) oils, and the oils extracted by SWE were even more resistant to lipid oxidation and more abundant valuable bioactive compounds than those of the cold-pressed(CP) oils.