Effects of superheated steam pretreatment on phenolics and its antioxidant activity in camellia oleifera oil

Camellia oleifera oil (COO) is a high-quality woody edible oil, and the oilseed pretreatment is an important part of the oil processing in the edible oil production. This study investigated the effect of superheated steam (SHS) pretreatment on the phenolics and the corresponding antioxidant properties of COO. Results showed that SHS pretreatment time and temperature had significant impact on oil yield and the phenolic content of different forms of camellia seeds (P<0.05). SHS pretreatment at 150 °C and 180 °C increased the free phenolics (FP) content, and the antioxidant properties of FP and conjugated phenolics (CP) in COO after SHS pretreatment under optimal condition. Then, the effect of SHS on two phenolic substances with high contents of COO, di-O-methylquercetin and 4-chloro-2-hydroxybenzoic acid was studied. SHS pretreatment had a positive effect on COO, and it may increase its biological activity and reduce its irritation. In addition, four phenolics that were significantly associated with the antioxidant properties of camellia phenolics were found. This study can provide new ideas and directions for oilseed pretreatment.