| Auricularia auricula is a kind of natural functional food whose nutrition and food values are very high. A.a containing essential body protein, fat, carbohydrates, calcium, iron, carotene, vitamin B1, B2, carbohydrates and minerals, it can make body strong, relief of pain and some other effects. China is a major producer of A.a, annual accounts for more than 90% of world production, study of the activity of functional components of A.a, and find the benefit of A.a in the future have great meaning.In this paper, A.a are used as raw materials, and sodium hydroxide solution as the extraction solvent. Extract melanin with classic methods, purify, characterized and have a preliminary study of the melanin of A.a (MA.a) physicochemical properties and stability, which can provide a theoretical basis for the development of new food additives.The main results are as follows:1. By comparison of different extraction techniques, single factor test, orthogonal test and range analysis, the optimal extraction MA.a conditions:ultrasonic-assisted extraction, ultrasonic extraction time of 80min, extraction power 80W extract concentration of 1.25mol/L, solid to liquid ratio of 1:30g/mL. The size of MA.a extraction factors were:ultrasonic power> extraction time> extract concentration> solid to liquid ratio. Under optimum conditions, the yield of 9.107% melanin, the color value of 514. Ultrasonic extraction method compared with conventional method, it have a short extraction time, pigment extraction rate, etc., this method can greatly increase productivity.2. MA.a through the alkali solution, acid hydrolysis and organic solvent off several proteins, lipids, and then had Sephadex G-75 gelcolumn chromatography purified, Besides, ultraviolet-visible, fourier transform infrared spectra (FT-IR), Scanning electronic microscope (SEM), X-ray energy dispersion spectroscopy (X-EDS) and elemental analysis identified MA.a was plteomelanin. The results revealed that:MA.a synthesis of melanin and tyrosine UV absorption maximum absorption wavelength at 207nm and 210nm, reported by different sources with the maximum absorption of melanin have the same wavelength. MA.a synthesis and tyrosinase IR spectra fundamental waveform characteristics similar contain -OH,-NH2,-CH,-COOH,-C=O, C-CH3 and other functional groups. By scanning electron microscopy to the ultrastructural MA.a for the heterogeneity of the sheet structure. MA.a x-ray spectroscopy analysis showed that, in extraction process, the raw materials from A.a to MA.a, MA.a the percentage content S atom increasing, which can be further inferred MA.a which compounds containing S. Element analysis results show that, MA.a the N element content was 6.85%, can infer MA.a brown melanin support.3. By studying physicochemical properties and stability of MA.a melanin, we find MA.a can dissolve in acidic solution, chloroform water, acid, salt solution, butanol, chloroform and other organic solvents, soluble in alkaline solution. MA.a was brown-black color of the solution. It has good performance of salt-resistant, preservatives-resistant and heat resistance, while the light-resistant is poor.4. MA.a in pyrogallol-luminol chemiluminescence system, CuSO4-Phen-Vc-H2O2 chemiluminescence system, H2O2-luminol chemiluminescence system, superoxide radical, hydroxyl radical and Hydrogen peroxide scavenging obviously, when MA.a concentration increases, the inhibition increased, showing a significant dose dependent, inhibitory rates of each system, IC50 were 246μg/mL,4.7μg/mL,1.8μg/mL, MA.a protection DNA damage also work better, in the CuSO4-Phen-Vc-H2O2-DNA chemiluminescence system in the IC50 is 9.5μg/mL... |
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