The Studies On Extration And Oxidation Characteristics Of Sesame Plant Sterols

Sesame is one of traditional oil crops in China, the current study of sesame more concentrated in the lignans, tocopherol, protein, flavor and process improvement, adulteration detection ect. While the phytosterol in seame is studied poorly. Previous research did not involve about extraction and oxidation characteristics on sesame phystestrol, this paper mainly studied these two aspects. In this paper the loss of phytosterol in sesame oil extracted by different methods is studied; it is concluded that sesame phytosterol retain the most content by supercritical CO2; On this basis, this paper discusses the optimum process conditions of extracting sesame phytosterothe by supercritical CO2 method; Finally the antioxidant characteristics in vitro and the high-temperature oxidation characteristics of sesame phytosterol in different media environment were studied.Comparing different extracting processes of sesame oils, to find the content of phytosterols in sesame oil extracted by aqueous method is lowest. The relative content of phytosterol is 70.99mg/kg. The content of phytosterol has little difference between in cold-pressed sesame oil and hot-pressed sesame oil. The relative contents of phytosterol are 889.19mg/kg and 928.91mg/kg. For leaching sesame oil, the amount of sesame oil phytosterols declines with the deepening of refining. The total amount of plant sterols declines from 471.30 mg/kg to 29.65 mg/kg. In the two processes of decolorization and deodorization, the quantity of phytosterols can separately lose up to 43.78% and 81.08%. The content of phytosterols in sesame oils by supercritical CO2 and subcritical butane extraction methods are relatively high, the relative contents of phytosterol are 2486.18mg/kg and 2277.37mg/kg.Phytosterols can be retained mostly by the method of SCF-CO2, so the optimum conditions for this method to extract sesame phytosterol are studied. First the effects of pressure, temperature, extracting time and flow rate of CO2 on the extraction rate of phytosterol are analyzed. Process conditions of supercritical CO2 method for extracting phytosterols from sesame oil are optimized via orthogonal experiment. Influence factors: flow rate of CO2 >extraction temperature>extraction pressure>extraction time, flow rate of CO2 is the most significant influence on extrcating sesame phytosterol, and the effect of extraction time is least. Supercritical CO2 conditions: 25 MPa, 2.5h, CO2 flow rate 20 L/h, temperature 55℃. Under this condition, the extraction rate is 72.69%.Antioxidant enhancing with Sesame phytosterols increasing is found in the study of Sesame phytosterols Antioxidant. When the addition amount of phytosterols reaches to 0.1%, there is same oxidation induction time of the oil with TBHQ’s, proving phytosterols have some antioxidant effects. In addition, the hydroxyl radical scavenging assay and DPPH radical scavenging assay proved that the sesame plant sterols have some antioxidant activity. Phytosterols derived from sesame oil sesame scraps, with the characteristics of no toxicity, emulsification and stability, sesame phytosterols can be developed into antioxidant health food auxiliary materials or functional ingredients and applied in health care industry.The study on high temperature oxidation characteristics of sesame plant sterols mainly are concentrated in the high temperature oxidation characteristics of tsesame plant sterols in air stearic acid, oleic acid. By changing the heating temperature and heating time, because of different heating temperature and heating time, oxidation degree of sesame phytosterols is also different, and the generation of oxides shows certain regularity: The seame phytosterols in more than 120℃ will be oxidized, the oxides are mainly hydroxyl compounds, compounds, ketones epoxidation; Under the same temperature conditions, there are more amount of oxide production in the higher temperature. The same temperature, with the prolongation of heating time, the oxide is reduced after the first growth trend; Short-term heating(1.5h inside), stearic acid oxidation sterols have some retardation; oleic acid has unstable structure, so the oxidation rate of sesame phytosterols is faster; At 180℃, sterol oxides generated more in air, and the oxide formed slightly less when sterol is heated in the stearic acid and oleic acid; In the heating process, the oxidation reaction of sesame phytosterols is a dynamic process.