番木瓜籽粕亚临界水提取物抗氧化活性研究

Study on antioxidant activities of extract by sub-critical water from papaya seed residues

目的评价亚临界水萃取条件对番木瓜籽粕抗氧化活性影响。方法采用不同温度的亚临界水对番木瓜籽粕进行不同时间的提取,通过测定番木瓜籽粕亚临界水提取液的FRAP值、对DPPH、ABTS·^+自由基的清除作用及还原能力评价其抗氧化能力。结果 FRAP法与还原能力评价番木瓜籽亚临界水提取液抗氧化活性呈相同趋势,随反应时间延长呈现先增大、后降低的变化规律;在温度上呈阶梯式分布,随温度升高而增大,低于160℃时,FRAP均值小于200μmol/L,还原能力的均值小于0.50;温度高于200℃时,FRAP均值大于280μmol/L,达260℃开始降低。对DPPH自由基在160℃、220℃这两个温度具有较高清除能力,清除ABTS·^+自由基则出现在160℃、240℃。结论亚临界水对番木瓜籽抗氧化活性的影响:温度>时间,对总抗氧化能力高温短时比低温长时间效果更佳,从节能高效角度采用亚临界温度240℃,反应10 min为最佳条件,可高效、环保、无试剂污染萃取出番木瓜籽粕中的抗氧化成分。

Objective To evaluate the effects of antioxidant activities of extraction of papaya seed residues in sub-critical water. Methods The antioxidant activities of extraction of papaya seed residues made in sub-critical water by different temperature and time were assessed by the methods of FRAP value, the clearance rate of DPPH and ABTS·+ and the reducing power. Results It was found that the same trend of antioxidant activities of extraction by FRAP value and reducing capacity which changed with time. The FRAP value and reducing power of extraction were increased with the rising of temperature till 260 ℃, which were revealed multistep distribution on temperature. When the temperature was lower than 160 ℃, the average FRAP was less than 200μmol/L, the average reducing capacity was lower than 0.50;when higher than 200 ℃, the average FRAP was more than 280μmol/L. The clearance rates of free radical of DPPH and ABTS·+had the same trend, the maximal clearance of DPPH was indicated at the temperature of 160 ℃ and 220 ℃, the ABTS·+ was emphasized at 160 ℃ and 240 ℃. Conclusion The factor was impacted significantly on the antioxidant activity of extraction preferred temperature than time. The effect of total antioxidant activity of extraction in sub-critical water of instantaneous high temperature was superior to that of low temperature for a long time. In consideration of energy-efficient, it was suggested that the extract of subcritical temperature 240 ℃ for 10 min could be as a preferable conditions.