Impact On Trace Nutrients And Antioxidant Activity Of Camellia Seed Oil In Processing

Camellia seed oil is a high quality woody edible oil endemic to China. In 2004, annul output of camellia seed and camellia seed oil are about 835000 and 835000 ton, respectively, in our country. The resource of camellia seed and oil are both very rich. The fatty acid of camellia seed oil is similar to olive oil. The unsaturated fatty acid content is over 90%, mainly are oleic acid and linoleic acid. Meanwhile, camellia seed oil is rich in tocopherol, sterol, squalene, polyphenol and carotenoids, which is a kind of high quality edible oil resources. But at present, the domestic processing of camellia seed oil still use the same as the bulk vegetable oil. The processing is relatively rough, which is easily lead to a substantial loss on trace nutrients. It will affect the quality and antioxidant activity of camellia seed oil. The quality of camellia seed oil can not compare with olive oil. Thus, this paper compares the quality of different varieties camellia seed oil, and the change of trace nutrients and antioxidant activity of camellia seed oil in the process have been discussed to analyze its quality vatiation. Besides, the correlation between trace nutrients and antioxidant activity is also studied.Firstly, the basic indicators, trace nutrients and antioxidant activity of twelve different camellia seed oil samples extracted with solvent are analyzed. Oil content of camellia seed is 38% to 57%, and moisture content is 1.80% to 6.12%. The acid value of camellia seed oil is 0.39 to 1.55 mg KOH/g and peroxide value is 0.14 to 1.32 mmol/kg, which both comply with the quality requirements of GB. The Oxidation stability index is 4.92 to 9.80 h, which express a good oxidative stability. Camellia seed oil mainly has palmitic acid, stearic acid, oleic acid and linoleic acid, the mean content respectively are 8.63%, 2.21%, 80.23%, 8.06%; the total tocopherol content is 138.44 to 371.67 mg/kg; total sterol is 1868 to 3382 mg/kg; squalene is 63.14 to 169.71 mg/kg; polyphenol is 7.34 to 21.87 mg/kg; β-carotene is about 4.00 mg/kg. The total polyphenol content shows a highly correlation with DPPH, ABTS, ORAC and FRAP free radical scavenging capacity(P<0.01); wherease, the highest correlation coefficients between the polyphenol content and antioxidant activity are obtained by the ABTS assay(R2=0.874).Next, the quality of camellia seed rude oil obtained by cold pressing, solvent extraction, aqueous enzymatic extraction and hot pressing are determined. Aqueous enzyme extraction oil has the lowest acid value(0.51 mg KOH/g) and the highest peroxide value(5.89mmol/kg); hot pressing oil(130 ℃) has the lowest peroxide value(2.78 mmol/kg). The proper heat treatment increases the content of sterol, squalene and polyohenol, while it reduces the tocopherol and β-carotetne content. What’s more, the harmful ingredient benzo(α) pyrene content is also increased. Thus, the following process should be controlled. Moreover, the heat treatment also improved the ability on free radical scavenging activity of camellia seed oil, and the antioxidant activity.Then, the camellia seed rude oil is stored under five conditions: at room temperature in dark, room temperature in light, 25 ℃ in dark, 25 ℃ in light and 4 ℃ in dark. This is order to investigate the effect of storage conditions on the quality of crude oil. During storage, tha acid value and peroxide value both increase obviously; oxidation stability index, tocopherol, squalene and polyphenol content declined sharply,while the decrease of sterol content is smaller, about 10%. Constant and low temperature in dark place can effectively slow down the quality of camellia seed rude oil deterioration.Finally, the change of quality of camellia seed oil in refining is studied. What’s more, the relationship between trace nutrients and antioxidant activity is also studied. After refining, acid value and peroxide value of camellia seed oil both decreased, which both can meet the National Standard. Tocopherol, sterol, squalene and polyphenol content are all losed during refining. Tocopherol and sterol content have the biggest loss in deodorization. The loss rates are 20.69% and 13.09% respectively. Squalene has the biggest loss in decolortion(24.99%). Polyphenol has the biggest loss in deacidification(80.50%). At the same time, benzo(α) pyrene which is harmful to human health also greatly decreased in decolortion(92.45%). The antioxidant activity of camellia seed oil is downward trend overall, especially after deacidification, the ability on free radical scavenging activity of camellia seed oil declined significantly, the rate of decrease are 54.70%, 50.54%, 60.07%, 58.80%, respectively. What’s more, polyphenol content is ratelated to ABTS, ORAC and FRAP assay(P<0.01), and to DPPH assay(P<0.05).