核桃内生真菌LTS-6-6代谢产物的体外抗氧化活性及对油脂氧化稳定性的影响

In Vitro Antioxidant Activity of the Metabolites of Walnut Endophytic Fungus LTS-6-6 and Their Effects on Oil Oxidation Stability

摘要:

以核桃内生真菌LTS-6-6为研究对象，通过ABTS自由基清除法、羟基自由基清除法及Fe3+还原能力测定等明确其代谢产物不同极性萃取物的体外抗氧化活性；采用Schaal烘箱法，以油脂过氧化值、酸值作为指标，测定添加高活性萃取物对菜（籽）油氧化稳定性的影响。研究结果表明，4种萃取物中，乙酸乙酯萃取物（Ethyl acetate extract，EAE）显示出较强的抗氧化活性，其对ABTS自由基、羟基自由基有较强清除能力（清除率≥80%），清除率高出石油醚萃取物（Petroleum ether extract，PEE）71.39%；EAE总酚和总黄酮含量为643.71 mg没食子酸/g和102.05 mg芦丁/g。添加0.02% EAE处理的菜（籽）油，在70 ℃下储藏8 d的过氧化值、酸值分别为5.88 mmol/kg、达到0.85 mg/g。由阿伦尼乌斯公式预测，在菜（籽）油中添加0.02% EAE时，20 ℃下储藏期为256 d，与空白组相比，延长192 d，说明添加EAE有效抑制了菜（籽）油氧化酸败。

Abstract:

Taking the walnut endophytic fungus LTS-6-6 as the research object, the in vitro antioxidant activities of different-polarity extracts of its metabolites were determined by the ABTS free radical scavenging method, the hydroxyl free radical scavenging method and the Fe3+ reduction ability assay; The Schaal oven method was used to determine the effect of adding highly active extracts on the oxidation stability of rapeseed oil using the peroxide value and acid value of oil as indicators. The research results showed that among the four extracts, ethyl acetate extract (EAE) showed a stronger antioxidant activity, and exhibited strong scavenging abilities for ABTS radical and hydroxyl radical (scavenging rate ≥ 80%). The clearance rate of EAE was higher (by 71.39%) than that of petroleum ether extract (PEE). The contents of total phenols and flavonoids in EAE were 643.71 mg gallic acid/g and 102.05 mg rutin/g. The peroxide value and acid value of the rapeseed oil treated with 0.02% EAE and stored at 70 ℃ for 8 days were 5.88 mmol/kg and 0.85 mg/g, respectively. As predicted by the Arrhenius formula, the rapeseed oil with 0.02% EAE had a storage period of 256 days at 20 ℃, which was 192 days longer than that of the blank group, indicating that the addition of EAE effectively inhibited the oxidative rancidity of rapeseed oil.