Psomiadou Eleni, Tsimidou Maria
Laboratory of Food Chemistry and Technology, School of Chemistry, Aristotle University of Thessaloniki, 54006 Thessaloniki, Greece.
J Agric Food Chem. 2002 Feb 13;50(4):722-7. doi: 10.1021/jf010847u.
Virgin olive oil samples with similar oxidative stabilities and fatty acid compositions were exposed to 12100 lx (25 +/- 1 degrees C) in closed bottles until bleached. The observed low changes in the substrate and polar phenols were related to oxygen availability. HPLC monitoring showed that pheophytin agradual degradation (> 90%) was accompanied by a considerable alpha-tocopherol loss (22-35%) due to the reaction of the latter with singlet oxygen. No changes were recorded for carotenoids, which acted as physical quenchers and light filters. Squalene loss was confined (4-12%). Complementary experiments on the activity of pheophytin a, using olive oil models, indicated a concentration dependence, enhanced by oxygen availability. In closed bottles, the degradation rate constant was higher at low amounts of pheophytin a. Squalene was preferentially consumed to protect alpha-tocopherol. An urgent change in the practice of packaging is needed to preserve the precious characteristics of the product during commercialization.
将具有相似氧化稳定性和脂肪酸组成的初榨橄榄油样品置于密闭瓶中，在12100勒克斯（25±1℃）条件下照射直至漂白。观察到底物和极性酚类的变化较小，这与氧气供应有关。高效液相色谱监测表明，由于脱镁叶绿素a与单线态氧反应，脱镁叶绿素a逐渐降解（>90%），同时伴随着大量α-生育酚损失（22-35%）。类胡萝卜素作为物理猝灭剂和滤光剂，未观察到变化。角鲨烯损失有限（4-12%）。使用橄榄油模型对脱镁叶绿素a活性进行的补充实验表明，其具有浓度依赖性，且氧气供应会增强这种依赖性。在密闭瓶中，脱镁叶绿素a含量较低时，降解速率常数较高。角鲨烯优先被消耗以保护α-生育酚。在商业化过程中，需要对包装方式进行紧急改变，以保留产品的珍贵特性。
