The peroxidizing effect of α-tocopherol on autoxidation of methyl linoleate in bulk phase
The peroxidizing effect of α-tocopherol on autoxidation of methyl linoleate in bulk phase
复制标题
α-生育酚对亚油酸甲酯本体相自氧化的过氧化作用
作者：
Junji Terao;S. Matsushita
为了了解α-生育酚在储存条件下对食用油自氧化机理的影响，在没有任何自由基引发剂的情况下，允许亚油酸甲酯在50℃下进行体相自氧化。还原后用高效液相色谱仪测定四种异构体过氧化氢(13-顺，反；13-反，反；9-顺，反；9-反，反)的生成量来监测反应。在没有α-生育酚的情况下，自氧化速率取决于样品大小，诱导期的持续时间受初始过氧化氢水平的影响。然而，无论样本量大小，c-t和t-t氢过氧化氢异构体的分布在繁殖期间保持不变。加入0.1%和1.0%的α-生育酚后，过氧化氢的量呈线性增加，c-t异构体的分布增加。氢过氧化速率似乎由α-生育酚的初始浓度决定，而不是由样品大小或初始氢过氧化值决定。抗坏血酸棕榈酸酯的存在抑制了α-生育酚的这种过氧化作用。对于α-生育酚对体相脂质自氧化的影响，提出了一种铬氧自由基参与的机制。因此，我们认为高浓度的α-生育酚影响食用油自氧化的机理。
In order to understand the effect of α‐tocopherol on the autoxidation mechanism of edible oil under storage conditions, methyl linoleate was allowed to autoxidize at 50 C in bulk phase without any radical initiator. The reaction was monitored by determining the production of four isomeric hydroperoxides (13‐cis,trans; 13‐trans,trans; 9‐cis,trans; 9‐trans,trans) by high performance liquid chromatographic analysis after reduction. In the absence of α‐tocopherol, the rate of autoxidation depended on the sample size, and the duration of the induction period was affected by the initial level of hydroperoxides. However, the distribution of c‐t and t‐t hydroperoxide isomers remained constant during the propagation period regardless of the sample size. The addition of α‐tocopherol at 0.1 and 1.0% caused a linear increase in the amount of hydroperoxides and elevated the distribution of the c‐t isomers. The rate of hydroperoxidation appeared to be governed by the initial concentration of α‐tocopherol rather than the sample size or the initial hydroperoxide level. This peroxidizing effect of α‐tocopherol was suppressed by the presence of ascorbyl palmitate. A mechanism in which chromanoxy radical participates is proposed for the effect of α‐tocopherol on lipid autoxidation in bulk phase. It is therefore suggested that α‐tocopherol at high concentrations influences the mechanism of autoxidation of edible oil.