采用PEG/盐的双水相系统纯化茶叶黄酮,探究萃取机理及其抗氧化活性。以茶叶为原料,茶叶黄酮得率为指标;采用单因素和响应面法试验设计,研究PEG的种类和用量、盐的种类和用量、温度、pH对茶叶黄酮提取率的影响,根据Box-Behnken中心组合方法进行3因素（Na2SO4的质量分数、PEG600、MgCl2添加量）3水平的试验设计,进行响应面（RSM）分析。通过分析还原力和DPPH体系,评估不同浓度黄酮的抗氧化活性,并与参照抗氧化剂BHT和Vc进行比较。结果显示最佳条件：pH为5,萃取温度30℃,5mL 15% Na2SO4,6g PEG600,MgCl2的添加量为2.9%,萃取率为96.31%。本方法所形成双水相体系,操作简便,萃取率高,方法重现性好;茶叶黄酮有较强的铁还原能力和清除DPPH自由基能力,茶叶黄酮是一个潜在的天然安全的有效的抗氧化剂。
To explore antioxidation capability and the extraction mechanism of the separation-purification of flavonoids from tea in aqueous two-phase systems, flavonoids from tea was taken as an index, to optimize the conditions for the extraction of flavonoids from tea, the effect of each factor such as weight and amounts of PEG, kinds and amounts of salt, temperature, pH have been studied by single factor and response surface methodology. Based on the single factor experiments, a three-factor (the amount of Na2SO4, PEG600, MgCl2) and three-level experiment design has been developed by Box-Behnken central composite design method. The antioxidant activity of different concentration flavonoids were assessed through reducing power assay, Scavenging effects on DPPH radicals and results were compared to reference antioxidant BHT and Vc. The result showed that the optimum conditions as follows, pH 5, the extracting temperature 30℃, the amount of 5mL Na2SO4 15%, the amount of 6g PEG600, the amount of MgCl2 2.9%, the extraction field 96.31%. The two aqueous phase system for flavonoid extraction is easy to get good reproductivity, and applied in mass production. The flavonoids from tea showed strong antioxidant activity. The flavonoids from tea are a potential product of natural safe and effective antioxidant.
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