超声处理核桃仁及其提取物的抗氧化性分析

目的]提取活性较高的核桃多酚,提高核桃的利用价值。方法]采用添加0.05 mol/L盐酸的70%乙醇溶液超声辅助的方法处理核桃仁,Folin-Ciocalteau法测定总酚含量,并测定其清除自由基能力及铁离子还原能力表征抗氧化活性。结果]4次超声提取(65℃,10 min)的核桃多酚提取液多酚含量为(12.03±0.16)mg/g,核桃仁中的多酚残留量为0.38 mg/g,低于碱处理后的核桃仁多酚残留量。此外,核桃多酚提取物在清除1,1-二苯基-2-三硝基苯肼(DPPH)自由基、2,2-联氮-二(3-乙基-苯并噻唑-6-磺酸)二铵盐(ABTS)自由基能力及铁离子还原能力均高于叔丁基对苯二酚(TBHQ)、VC和VE。结论]酸化乙醇超声处理核桃仁不仅可以有效去除核桃多酚,还为食品工业提供了高活性的天然抗氧化剂。

Ultrasonic Extraction of Walnut (Juglans regia L.) Kernel and Analysis of the Oxidation Resistance of the Extracts

Objective] To extract polyphenols from Juglans regia L.with realtivley high activity, and to enhance the utilization value of J.regia. Method] Ultrasonic extraction was applied directly to process J.regia kernel by adding 70% ethanol containing 0.05 mol/L hydrochloric acid. The total phenol content was measured by Folin-Ciocalteu method.The antioxidant activity was evaluated using free radicals scavenging capacity and iron ion reducing ability.Result] As for the four times ultrasonic extraction (65 ℃, 10 min) of J.regia extracting solution, polyphenols content was (12.03 ±0.16)mg/g walnut kernel;The remained polyphenols in the kernel was 0.38 mg/g walnut kernel, which was lower than that in walnut kernel treated with conventional alkali soaking method.Compared with t-butyl hydroqumone (TBHQ) and vitamin C, walnut poly-phenol extract showed superior antioxidant capacity in terms of scavenging free radicals and reducing iron ion . Conclusion] Direct ultrasonic ex-traction of walnut kernel not only removed polyphenols with high efficiency but also provided potential antioxidant additive for food industry .