Ultrasonic-assisted extraction (UAE) and maceration extraction (ME) were optimized using response surface methodology (RSM) for total phenolic compounds (TPC) from fresh olives. The main phenolic compounds and antioxidant activity of TPC were also investigated. The optimized result for UAE was 22mL/g of liquid-solid ratio, 47°C of extraction temperature and 30min of extraction time, 7.01mg/g of yielding, and for ME was 24mL/g of liquid-solid ratio, 50°C of extraction temperature and 4.7h of extraction time, 5.18mg/g of yielding. The HPLC analysis revealed that the extracts by UAE and ME possessed 14 main phenolic compounds, and UAE exhibited more amounts of all phenols than ME. The most abundant phenolic compounds in olive extracts were hydroxytyrosol, oleuropein and rutin. Both extracts showed excellent antioxidant activity in a dose-dependent manner. Taken together, UAE could effectively increase the yield of phenolic compounds from olives. In addition these phenolic compounds could be used as a potential source of natural antioxidants.

Seed cake protein (SCP) from Camellia oleifera was hydrolyzed by five commercial proteases (Flavorzyme, Trypsin, Neutrase, Papain, Alcalase). Amino acid composition, molecular weight distribution, antioxidant activity and functional property of the seed cake protein hydrolysates (SCPH) were investigated. Enzymatic hydrolysis improved protein solubility significantly but impaired the foaming and emulsifying property. Hydrolysate generated by alcalase had the highest hydrolysis degree (DH) and antioxidant activity, and displayed excellent protein solubility over wide range of pH, while hydrolysate prepared by flavorzyme showed better copper chelating capacity and emulsifying stability with low molecular weight distribution. Trypsin-treated SCPH showed better foaming property than original protein. The results indicated that enzyme type greatly influenced the molecular weight, functional property and antioxidant activity of SCPH. It was also found that electing appropriate protease and controlling the DH could be enhanced or reduced functional property according to actual applications.

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