| Natural pigment has been one of the research and application focus in food.Dragon fruit peel contains a lot of water-soluble natural pigments, and the color isbright purple, which is natural edible red pigment extraction and processing applicationsfor high-quality source material. In the food industry, it is used for fruit juice, cakes,candy, and it also can be applied to cosmetics R&D and productions. It has a highresearch value and application of natural edible pigment. And Electrochemical analysistechnique can be used to analyze the substance with redox properties, which is a kind ofmethod for the determination of fast and efficient. Pigment from Pitaya was extractedwith ultrasonic, and the pigment was purified and refined. And study on the structureidentifications and electrochemical behaviors of Pigment. The main contents were asfollows:The effects of extraction condition including different solvents, ultrasonic time,liquid material ratio, pH value, and temperature were investigated. In this paper, theextraction conditions with volume percentage concentration of40%alcohol solution assolvent, the pH value was5, solid-liquid ratio was2:1, temperature is40℃, andultrasonic time was45min were optimal. The purified technology was improved asfollows: Crude extract was filtrated with0.22μm microporous membrane. Thepetroleum ether was instead of ether lipids as addition agent. Dialysis method was usedto removal of inorganic ions, sugars and other substances. This method was much moreconvenient operation and lower cost. And the color value of Pitaya pigment was120.6,which was1.6times of published values.The structures of Pitaya peel pigment were tested with the methods of UV-VIS,FTIR, and HPLC-MS. The results showed that there were7mainly substances in thepigment, which were Betanidin, Isobetanin, Phyllocactin, Isophyllocactin, Hylocereninb,Betanidin-5-O-β-sophoroside and Betanin. In addition, the methods of CV and DPVwere used to study the electrochemical behaviors of pigment. The research showed thatthe oxidation peak of pigment was Epc=0.223V, which explained the pigment wasoccurred irreversible redox reaction. And the reaction which occurred presumably asaldehyde group of cyclo-2-hydroxyphenylalanine-5-O-glycoside was oxidized into acid.With increasing concentrations of AA, the oxidation peak of pigment was moved from0.22V to0.275V and the oxidation peak current was increased. It was shown that the oxidation reaction capacity of the pigment was enhanced, which was conducive to thestability of the pigment.This paper also studied the light, temperature and metal ions on the stability of thepigment, and the antioxidant capacity of pigment by ABTS. The results as follows: theeffect of ultraviolet light was larger than monochromatic light on stability of pigment.The reason may that ultraviolet light destroyed structures and caused the ultravioletpeotolysis or photooxidation of the pigment. Pigment was relatively stable at below50℃. And Ca2+, Mn2+, Mg2+, Na+, K+metal ions had no great effects on pigment color.In addition, the preservation of pigment should be avoided Fe3+, Cu2+, Zn2+, Al3+metalion exposure. And the higher concentration of pigment, the more stronger of antioxidantpower. |
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