Abstract

There is a recognized need for exploring new natural antioxidants that have high antioxidant potential. Thus, the aim of this study was to optimize the extraction process of onion peels using ultrasound- and enzymatic-assisted extractions (UAE and EAE) methods to utilize the optimal extracts as natural antioxidants. Box–Behnken Design (BBD) was implemented to reach the optimal extracts with the highest simultaneous content of total phenolic content (TPC) and total flavonoid content (TFC). The optimal UAE and EAE extracts were subjected to High Performance Liquid Chromatography (HPLC) analysis to identify their chemical profile. The antioxidant activities of optimal extracts obtained by UAE and EAE were evaluated in vitro using DPPH and FRAP assays and their abilities to increase the oxidative stability of sunflower oil were studied using Rancimat test. The optimal conditions for UAE were 34.02 W, 26.87 mL/g solid, and 45.43 min, meanwhile they were 30.00 mL/g solid, 45.43 min at enzyme concentration of 0.52% for EAE method. DPPH and FRAP assays results revealed that EAE optimal extract show superior antioxidant activity over UAE optimal extract. The protection factor of optimal EAE extract against sunflower oil oxidation was close to that of butylated hydroxytoluene (BHT).

摘要

人们认识到需要探索具有高抗氧化潜力的新型天然抗氧化剂。因此，本研究的目的是使用超声波和酶辅助提取（UAE 和 EAE）方法优化洋葱皮的提取工艺，以利用最佳提取物作为天然抗氧化剂。采用 Box-Behnken 设计 (BBD) 以获得总酚含量 (TPC) 和总黄酮含量 (TFC) 同时含量最高的最佳提取物。对最佳的 UAE 和 EAE 提取物进行高效液相色谱 (HPLC) 分析，以确定其化学特征。体外评估了 UAE 和 EAE 获得的最佳提取物的抗氧化活性使用 DPPH 和 FRAP 测定法，并使用 Rancimat 试验研究了它们提高葵花籽油氧化稳定性的能力。最佳UAE条件为34.02 W、26.87 mL/g固体和45.43 min，而EAE方法在酶浓度为0.52%时为30.00 mL/g固体、45.43 min。DPPH 和 FRAP 测定结果表明，EAE 最佳提取物显示出优于 UAE 最佳提取物的抗氧化活性。最佳 EAE 提取物对葵花籽油氧化的保护系数接近丁基羟基甲苯 (BHT)。