An aqueous enzymatic extraction method was developed to extract oil from camellia seed (Camellia oleifera Abel.). Individual enzymes and combinations of enzymes, pH, the ratio of material to water, reaction time and methods of demulsification were studied. The effects of hexane and aqueous enzymatic extraction on the oil's physicochemical properties (acid value, peroxide value, fatty acid profile, phenolics, and phospholipids content) were compared. The combination of protease/cellulase yielded significantly more oil than did other combinations. Under the optimal reaction conditions, a free oil yield of 82.37% was obtained. Four types of demulsification methods were compared. After demulsification with 20% ethanol (v/v), the highest total free oil yield of 91.38% was achieved. Compared with hexane-extracted oil, aqueous enzymatic-extracted oil was more acidic; had a higher percentage of monounsaturated fatty acid and contents of vitamin E and squalene; and had lower peroxide values, percentage of total saturated fatty acid, polyunsaturated acid, and content of both total phenolics and total phospholipids.Practical applications: The current work will contribute to an efficient enzymatic extraction method for camellia seed oil and help with the develop a method to demulsify the emulsion.

Volatile compounds of Camellia seed oils from 5 different varieties were characterized by headspace solid phase microextraction/ gas chromatography/mass spectrometry (HS-SPME/GC/MS). Four parameters of SPME were optimized and the best extraction conditions were: 50/30 μm DVB/CAR/PDMS fiber, 45℃ and 45 min of SPME, and 4.00 g sample size. Forty-six volatiles were identified, including 16 aldehydes, 10 alcohols, 4 acids, ketones, 3 terpenes and 6 esters. Further correlation analysis between aroma compounds and sensory attributes revealed pentanal, hexanal, (E)-2-hexenal, octanal, (E)-2-heptenal, nonanal, (E)-2-octenal, (E)-2-decenal, (E,E)-2,4-heptadienal, 2-hexanol, 2-heptanol, hexanol, octanol, acetic acid, pentanoic acid, 1-p-menthene, limonene, γ-terpinene, ethyl-2-methylbutanoate, 2-methylbutyl acetate, ethyl 2-methyl-2-butenoate, γ-butyrolactone, γ-hexalactone were the important characteristic aroma compounds of Camellia seed oils. Additionally, electronic nose (e-nose) was applied to analyze the aroma of Camellia seed oils. HS-SPME/GC/MS and e-nose techniques combined with multivariate analysis can be used to distinguish between different Camellia seed oils.

To understand the influence of different extraction methods on properties of Camellia seed oil, the physicochemical properties, fatty acid composition, bioactive compounds content of camellia seed oil extracted by aqueous enzymatic extraction, expeller pressing, organic solvent extraction and supercritical CO 2 extraction were investigated. No significant differences were found among acid values of extracted oils. The peroxide value of hexaneextracted oil and expeller-pressed oil was significant higher than aqueous enzymatic-extracted oil and supercritical CO 2 -extracted oil. The major fatty acids present in camellia seed oil were palmitic acid, stearic acid, oleic acid, and linoleic acid. No significant differences were found in the amounts of the major fatty acids in the oils. The aqueous enzymatic-extracted oil had a higher content of total monounsaturated fatty acids, α-tocopherol, β-carotene, squalene and phytosterol than hexane-extracted and expeller-pressed oils. Nine phenolic acids were detected in camellias seed oils, and 3-hydroxytyrosol, benzoic acid, catechins, 4-hydroxybenzoic acid and chlorogenic acid were the predominant compounds. The content of phenolic compounds in the aqueous enzymatic-extracted camellia seed oil was lower than that of other extracted oils. The phospholipid content of the aqueous enzymatic-extracted oil and the supercritical CO 2 -extracted oil was significantly lower than that of hexane extracted oil and expeller pressed oil.Keywords: Camellia seed oil (Camellia oleifera Abel.), aqueous enzymatic extraction, expeller pressing, organic solvent extraction, supercritical CO 2 extraction, physicochemical properties, lipid composition IntroductionCamellia (Camellia oleifera Abel.) is a common oil-bearing woody plant in southern China, and camellia seed oil has been used extensively in China for cooking over 1,000 years (Zhong et al., 2007) and also as a traditional medicine for stomachaches and burns (Lee et al., 2006). At present, the planting area of the Camellia plant is more than 4 million hectares, and camellia seed oil production is approximately 250 million kilograms (Zhuang, 2008). Camellia seed oil is important edible oil that is pleasanttasting and has a fatty acid profile similar to that of olive oil, with oleic acid as the predominant fatty acid (74 _ 85%). Oils high in oleic acid have been demonstrated to be very stable, even at high temperatures such as those used to fry food (Abdulkarim et al., 2005; Warner et al., 1997).Hydraulic pressing, expeller pressing and organic-solvent extraction are the most common methods for recovering oil from seeds (Rosenthal et al., 1996). At present, camellia seed oil is obtained either through hexane extraction or a process that combines expeller pressing and hexane extraction (Zhang et al., 2012). These methods are very effective, providing an oil yield greater than 95% (Xie et al., 2011). However, considering the safety and environmental issues associated with the use of hexane, methods other than hexane-based extraction h...