Study Of Technologies On Refining High Quality Tea Seed Oil And Comprehensively Utilizing Tea Seed

Tea plant (Camellia sinensis (L.) O,Kuntze), native to tropical and subtropical regions in China, belongs to Family Theaceae. It is a small evergreen tree up to 16 m tall, usually pruned back to shrubs in cultivation for its leaves. Tea seed is a sideline product in tea cultivation. The tea seed production per year is about 450 million kg in China, based on 1.2 million ha of tea gardens (not including Taiwan Province) with 375 kg seed per ha. My dissertation research was focused on tea seed biochemistry ingredient, oil fatty acid composition, oil extraction and refining conditions, and production conditions with the procedures of extracting tea starch, tea saponin, and activated carbon. This extensive study is to provide the technical support for comprehensively utilizing the tea seed resources, which is significantly important to the tea industry's enhancing the economic efficiency and development.The dissertation study covers the following six topics:1. Cell morphology of tea seed and physical and chemical analysis: The research of the cell morphology included observing the cotyledon cell structures of the tea seed with an optical microscope and measuring the cell size, cell wall thickness, and the sizes of fat body and starch granules within the cell. The contents of tea seed, such as fat, starch, tea saponin, protein, and total sugar were determined with chemical methods. The data will provide the theoretical basis to screen the tea seeds from appropriate varieties of tea plants as raw materials for tea seed oil extraction and comprehensive utilization.2. Analysis of the fatty acid components in tea seed oil: The fatty acid components of tea seed oil were measured by gas chromatography from 24 varieties of tea plants, showing 38.763%～56.609% oleic acid, 20.296%～37.502% linoleic acid, 14.152%-18.828% palmitic acid, and 2.905%～5.560% stearic acid in content range with the averages of 49.786% oleic acid, 27.456% linoleic acid, 16.159% palmitic acid, and 3.994% stearic acid. Comparing the components of tea seed oil with other cooking oil, provides the foundation for the tea seed oil distinction and quality evaluation.3. Study of tea seed oil extraction: The tea seed oil was extracted separately with aqueous-enzyme method, organic solvent method, and supercritical CO₂ method. For the aqueous-enzyme method, the optimum condition is with the granule size 40-60μm, 3.5: 1 ratio of water to tea seed material, and for 40 min at 90℃. For the organic solvent method, the favorable condition is solvent leaching for 1.5 hours at 35℃, with 2: 1 ratio of solvent to tea seed material and drying raw material at 80℃. For the supercritical CO₂ method, the optimal condition is with the extracting pressure 35MPa at 40℃for 3.0 hours and 40～60mesh of the granule size of raw material. After comparing the pros and cons with these three methods, it was found that the organic solvent method was the best for the tea seed oil extraction, while aqueous-enzyme method was better for both tea seed oil extraction and tea seed comprehensive utilization.4. Study of the procedures of refining tea seed oil: Using the conventional methods, the fatty acid components and several important physical and chemical measurements were compared with various procedures of refining tea seed oil. The optimum condition for refining is with the temperature at 30℃and the concentrations of 18°B'e caustic soda and 0.2% extra caustic soda. The optimal condition for bleaching is with the temperature at 100-110℃for 25 minutes and the dose of bleaching clay 2.5%～3.0% . The deodorization temperature is suitable from 180℃to 200℃for 1 hour. Winterizing time requires at least 8 hours with temperature maintained within 6-8℃for lipid crystallite forming and filter temperature maintained at 10℃during chilled oil filtration.5. Comprehensive utilization of tea seeds: The production procedures and conditions of extracting tea starch, tea saponin, and activated carbon were studies.(1) The conditions for tea starch production: Soak tea seed kernel in water for 2 hours at 40℃. When beating, the liquid-solid ratio is 1.7:1. For separation, temperature is 50℃. With these conditions, the starch extraction rate is 82.61%. The components of the starch extraction include 0.35% crude protein, 0.28% crude fat, 8.51% moisture, and 87.5% starch. The starch pellet looks circular with smooth surface, containing 23.16% amylose and 74.39% amylopectin with good stability of cool viscosity. The pellet size is between 4.1～13.2μm with the mean diameter 7.92μm. The characteristics of tea starch are similar to the sweet potato starch.(2) The conditions for tea saponin production: To make better outcome, for the tea saponin extraction, the optimum condition is suggested with water temperature at 80℃, with the 4:1 ratio of water to tea seed materials, leaching for 2 hours, and 3 times of stage countercurrent contact extractions. For tea saponin purification and concentration, it is found to be better when 30% poly aluminum chloride is used at impurities coagulating with the amount of 1.0%～1.5% liquid total weight .For precipitating, the amount of precipitating agent used is 2.5% -4.0% of total weight. It is suitable for 1 unit of CaO to react with 2-2.7 units of tea saponin.(3) The conditions for making activated carbon from tea seed shell: To produce activated carbon form tea seed shell with the zinc chloride activation method, the ratio of liquid (50% zinc chloride) to tea seed shell materials should be 2.5:1. The temperature for 1 hour activation is 400℃.