【摘要】 本研究采用电子顺磁共振波谱仪和紫外分光光度计,分别测定不同热处理方式和时间下,亚麻酸中持久性自由基信号和化学结构特征,以期探究亚麻酸结构变化及其自由基形成位点间的关系.结果表明,亚麻酸在电炉加热和微波复热后均能产生自由基,且复热后样品中的自由基信号强度明显增强,并随微波复热时间的增加而增强.这归因于电炉加热对亚麻酸起到启动作用,并提高其分子极性,而后在氧气的引入和微波辐射的作用下,导致其共轭双键断裂,进而产生以氧为中心的自由基（g因子值> 2.0040）.微波复热时间增加时,衰减速率常数K随之增加,相应的,半衰期t_1/2随之减少.这是由于随着微波复热时间的增加,产生的较短寿命、高自旋的自由基增多.亚麻酸样品的羟基自由基随微波加热时间的增加而增强,这是因为微波加热有利于促进过氧化物的生成及其O—O键的断裂,进而贡献羟基自由基的形成.更多还原

【Abstract】 This study aims to investigate the relationship between the linolenic acid（LNA） structure alternation and generation of persistent free radicals（PFRs）. In the experiments, LNA samples were heated by electric stove and microwave for different time. The structure of the treated samples and PFRs generation were characterized by（UV-Vis） spectroscopy and electron paramagnetic resonance（EPR） techniques. The results showed that both electric stove heating and microwave reheating of LNA generated PFRs. The intensity of the PFRs signal increased with the microwave reheating time. Breaking of chemical bonds in LNA with consequent rise in polarity initiated PFRs generation due to electric stove heating. In the presence of oxygen, destruction of the conjugated double bonds enabled growth of oxygen-centered free radicals（g factor value > 2.0040）. Increasing microwave reheating time elevated the decay rate constant K and reduced the half-life(t_1/2). Significant rise in the number of short-lived high-spinning radicals with increasing microwave reheating time attributed to this phenomenon. The increasing concentration of hydroxyl radicals indicated that microwave heating led to the peroxide generation and subsequent breakage of O—O bonds during LNA degradation.更多还原