Unilever R&D Vlaardingen, Olivier van Noortlaan 120, 3133 AT, Vlaardingen, The Netherlands.
Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands.
Anal Bioanal Chem. 2018 Sep;410(22):5421-5429. doi: 10.1007/s00216-018-1101-z. Epub 2018 May 10.
Lipid oxidation reactions in foods rich in healthy unsaturated fatty acids result in the formation of a wide range of oxidation products that can have adverse effects on food quality and safety. To improve the understanding of oxidation reactions and methods for their inhibition, detailed information on the type and levels of the oxidation products formed is required. Accurate measurement of lipid oxidation products, especially of the non-volatile aldehyde products, has so far been a challenge due to the low sensitivity and limited specificity of most analytical methods. Here, a novel normal-phase LC method that uses selective labeling of aldehydes and epoxides with 7-(diethylamino)coumarin-3-carbohydrazide (CHH) is described. Labeling of alkanals is quantitative within 10 h. For alkenals, conversion is only around 50% at 24 h reaction time. Detailed MS identification of all aldehydes and epoxides is possible by using high-resolution MS and data-dependent MS acquisition. Fluorescence detection was successfully used to quantify groups of oxidation products. Sensitivity was high enough to allow accurate quantification even in fresh mayonnaises, where levels of around only 0.3 g total aldehydes/kg oil were found. Individual species can be quantified by MS if suitable reference standards are available. If no standards can be used, semi-quantification using an average response factor is an option. Clearly, the novel derivatization method is suitable for monitoring secondary lipid oxidation products in the early stages of shelf life. This makes it an important tool for developing improved food products. Graphical abstract Selective labeling of low and high molecular weight lipid oxidation products with 7-(diethylamino) coumarin-3-carbohydrazide for identification and semi-quantification.
富含健康不饱和脂肪酸的食物中的脂质氧化反应会导致形成广泛的氧化产物，这些产物可能对食品质量和安全产生不利影响。为了更好地了解氧化反应及其抑制方法，需要详细了解形成的氧化产物的类型和水平。由于大多数分析方法的灵敏度低且特异性有限，因此准确测量脂质氧化产物，尤其是非挥发性醛类产物，一直是一个挑战。在这里，描述了一种新的正相 LC 方法，该方法使用 7-(二乙氨基)香豆素-3-甲酰肼 (CHH) 选择性标记醛和环氧化物。在 10 h 内定量测定烷醛。对于烯醛，在 24 h 的反应时间内转化率仅约为 50%。通过使用高分辨率 MS 和数据依赖 MS 采集，对所有醛和环氧化物进行详细的 MS 鉴定。可以使用荧光检测成功地对氧化产物组进行定量。灵敏度足够高，即使在新鲜蛋黄酱中也可以进行准确的定量，在新鲜蛋黄酱中发现的油中总醛含量约为 0.3 g/kg。如果有合适的参考标准，则可以通过 MS 对单个物质进行定量。如果无法使用标准，则可以使用平均响应因子进行半定量。显然，新的衍生化方法适用于在货架寿命的早期阶段监测次要脂质氧化产物。这使其成为开发改良食品的重要工具。示意图 用 7-(二乙氨基)香豆素-3-甲酰肼选择性标记低和高分子量脂质氧化产物，用于鉴定和半定量。
