基于天然绿色棉色素含有多酚类物质以及其结构的不稳定性，采用清除1，1⁃二苯基⁃2⁃苦基肼（ DPPH）自由基法，探讨温度、光辐射、酸碱条件对绿色棉色素的抗氧化活性的影响。结果表明，高碱条件对绿色棉色素的抗氧化影响较大。经pH值为13的碱溶液处理后，色素的DPPH自由基清除率下降至2�97％，调回中性后，自由基清除能力恢复至原先的81�38％，说明碱性条件导致抗氧化性的消失大部分可以恢复。结合紫外光谱可以看出，碱性条件下色素主体结构不变，但部分组分结构发生了不可逆的破坏。光辐照对天然绿色棉色素的抗氧化活性有明显的影响，日晒5 d后，绿色棉色素自由基清除能力下降57�10％。高温150℃处理1 h对绿色棉色素的自由基清除能力影响不大。%Based on polyphenols pigment of natural green cotton and its structural instability, the 1⁃diphenyl⁃2⁃picrylhydtazyl ( DPPH ) radical scavenging method was used to study the effects of temperature, light irradiation and acid⁃base condition on the antioxidant activity of green cotton pigment. The results showed that high alkali conditions had great influence on the antioxidant stability of natural green cotton. The DPPH radical scavenging activity of green cotton pigment decreased to 2�97% when the pigment was treated in the alkali solution with the pH value of 13. When adjusted to be neutral, green cotton pigment recovered to 81�38% of its original radical scavenging capability, indicating that most of radical scavenging capability lost resulted from the alkaline condition was recoverable. The ultraviolet spectra measurements demonstrated that the main structure of pigment was unchanged under the alkaline condition, but some components structure of the pigment had changed irreversibly . Light irradiation had significant effect on antioxidant activity of the pigment of naturally green cotton. The radical scavenging capability of green cotton pigment dropped to 57�10% when the pigment was exposed to the sun light for 5 d. It was found that no significant change in radical scavenging capability of green cotton pigment was caused when treating the pigment at 150 ℃ for 1 h.
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