| China is the country which has the highest yield, the most abundance cultivars and the most widely distributed of oil-tea camellia seeds in the world. With the expanding of the camellia acreage and the deepening of its processing technology, the production of oil-tea seed cake, the squeezed byproduct, was increasing rapidly. Because the tea saponin, contained in the oil-tea seed cake, has a bitter taste and a pungent smell, which makes it toxic to cold-blooded animals, it is not ideal for the tea seed cake to be used as a fertilizer or a feed. Tea seed cake is often discarded as waste or accumulated, resulting in a lower utilization of processing. It will have good economic and social benefits if we can extract the active substances, such as, tea saponin, tea polysaccharide, tea polyphenols, and make the residue into feed or compound fertilizer. In this paper, the tea seed cake was utilized. The extraction, separation and purification process of tea saponin, the separation and purification method of tea polysaccharide and tea polyphenols in byproduct, as well as the physical and chemical properties of tea saponin ending product were system studied.Firstly, the extraction process of tea saponin was comparatively studied.(1)Heating reflux extraction(HRE) process was used. The optimal conditions were confirmed by experiments via single factor and orthogonal methodology:ethanol concentration was60%, solid-liquid ratio is1:20(g/mL), temperature is controlled at70℃, extracting time is2h and extracting times is twice. Under the optimal conditions, the extracting efficiency was (17.43±0.13)%.(2)The optimized conditions of the simultaneous ultrasonic and microwave assisted extraction(UMAE) technique were as follows:using ethanol of60%concentration as extracting solvent, microwave power was500W, solid to solvent ratio was1:15(g/mL),120s of extraction time and two times of extraction. The yield of UMAE was (17.84±0.09)%.(3)Selecting the ionic liquids [bmin]BF4of2.0mol/L as solvent, creatively, the ultrasonic and microwave-assisted solvent extraction of tea saponin from tea seed cake were investigated, the yield can reach (18.49±0.08)%, the results indicated that the method had a reduction of extraction time and an improvement of efficiency compared with HRE and UMAE, and provided a new way of thinking for the extraction of tea saponin.Secondly, the separation and purification of tea saponin was studied. AB-8was chose to isolate tea saponin. On adsorption, the loading volume was100mL, the concentration of tea saponin in feed solution100.18mg/mL, flow velocity1BV/h; on desorption, gradient elution step was firstly pure water, secondly the40%ethanol, finally80%ethanol, flow rate2BV/h. Under the optimal conditions above, gradient elution part1-,2and3were obtained. The part3was the tea saponin ending product with the purity of tea saponin of (98.33±1.12)%.And then, further separation and purification of gradient elution part1and2were studied. Using n-butanol extraction method to purify part1(purity of tea saponin:30.76%, tea polysaccharide:68.35%), the purity of tea polysaccharide obtained was (95.97±0.62)%after six times of extraction; adopting heating reflux method to purify part2(purity of tea saponin:85.26%, tea polysaccharide:13.96%) with anhydrous ethanol, the purity of tea saponin in residue reached (99.00±0.56)%after a return. Finally, the basic physical and chemical properties of tea saponin ending product were identified and analyzed. We can confirm that tea saponin of high purity is light in color and has good foamability, foam stability and surfactivity by comparing with that of low purity. The melting point of tea saponin was verified by Differential Scanning Calorimetry technology. The chemical constitution of tea saponin ending product was consistent with that of standard product, verified by Infrared Spectrum. |
PDF Full Text Request