Study On The Separation, Identification And Stability Of Carotenoids From Persimmon Peel

As a big family of the ecosystem in the world, carotenoids provide the beautiful color for every creature. Carotenoids are also an assistance dye for photosynthesis and, they can participate to some important physiological process such as transform light to energy, quench single oxygen and free radical. Carotenoids can protect creatures from suffering the deleterious environmental factors, which is a significant meaning for the normal running of the ecosystem ^[1].In this thesis, a study on the extraction of carotenoids from persimmon peel was carried out. The persimmon peel was used as the research object to extract carotenoids. The extraction conditions of carotenoids have been investigated. The purification and the analytical method of carotenoids have been established. In order to provide some theoretical reference for the application and preservation, the stability of carotenoids were also studied.Carotenoids were extracted by solvent method and the extraction rate was analyzed by ultraviolet-visible absorption spectroscopy (UV-vis). The factors that influence the extraction result such as the type of solvent, the granularity of raw materials, solid-to-liquid ratio, the temperature and the extraction time have been studied. By the experiments above, the influence trend of each factor has been detected and the factors that have significant effect on the extraction were found out. Through orthogonal experiment, the best extraction technological condition of persimmon carotenoids was: acetone as extraction solvent, solid-to-liquid ratio 1:20 g/mL , at 60 ℃ for 2.5 h and extracted twice. Under that condition, the extraction rate of carotenoids was 80.74 mg every 100 gram dry persimmon peel. Some large-scale experiments were conducted based on the condition above and the results suggested that the industrialization of the extraction of carotenoids from persimmon peel was feasible.The carotenoids compound of persimmon peel were separated and purified by thin layer chromatography (TLC) and column chromatography. Four kinds of main ingredient in the persimmon peel were determined by TLC, the R_f were 0.901, 0.794,0.378,0.299 respectively. Through the main experiments, the optimal separation condition of column chromatography was: solid-phase was silica gel, the quality of silica gel-to-carotenoids ratio was 20:1, petroleum ether-acetone (10:3,V/V) as washing solvent, washing velocity was 3.0mL/min. The carotenoids were separatedbased on the condition above and the results suggested there were four compounds in the persimmon carotenoids, which were consistent with TLC. By color reaction, the mensuration of Rf, and the measurement of UV-vis, high performance liquid chromatography (HPLC), infrared spectroscopy (IR) and nuclear magnetic resonance(NMR), at the same time, with the relevant results of standard substances from UV-vis, HPLC, IR and NMR , we can give a qualitative conclusion that the four kinds of main ingredients in persimmon peel are 3 -carotene, lycopene, zeaxanthin and lutein respectively.Finally, the various factors that influence the stability of the persimmon peel carotenoids were studied and the results indicated: Light, heat, solvent medium and oxygen have great effect on carotenoids compound;Sugar, vitamin C, salt and other common food additives have protective function to carotenoids;Carotenoids are stable in the environment of Mg2+, Ca2+, Zn2+, Sn2+ and K+, Fe3+, Fe2+, Al3+, Cu2+and I" can destroy the compound greatly and they will accelerate the decomposition of carotenoids. The whole study of this thesis will provide some theoretical and experimental reference for the application, transportation and preservation of persimmon peel carotenoids.