Márquez-Ruiz Gloria, Holgado Francisca, Ruiz-Méndez María Victoria, Velasco Joaquín
Instituto de Ciencia y Tecnología de Alimentos y Nutrición, Consejo Superior de Investigaciones Científicas (ICTAN-CSIC), 28040 Madrid, Spain.
Instituto de la Grasa, Consejo Superior de Investigaciones Científicas (IG-CSIC), 41089 Sevilla, Spain.
Foods. 2021 Aug 29;10(9):2035. doi: 10.3390/foods10092035.
Chemical changes occurring in dietary lipid oxidation compounds throughout the gastrointestinal tract are practically unknown. The first site for potential chemical modifications is the stomach due to the strong acidic conditions. In this study, model lipids representative of the most abundant groups of dietary oxidation compounds were subjected to in vitro gastric conditions. Thus, methyl linoleate hydroperoxides were used as representative of the major oxidation compounds formed in food storage at low and moderate temperatures. Methyl 9,10-epoxystearate, 12-oxostearate and 12-hydroxystearate were selected as model compounds bearing the oxygenated functional groups predominantly found in oxidation compounds formed at the high temperatures of frying. Analyses were performed using gas-liquid chromatography/flame ionization detection/mass spectrometry and high performance-liquid chromatography/ultraviolet detection. Losses of methyl 9,10-epoxystearate and linoleate hydroperoxides in the ranges 17.8-58.8% and 42.3-61.7% were found, respectively, whereas methyl 12-oxostearate and methyl 12-hydroxystearate remained unaltered. Although quantitative data of the compounds formed after digestion were not obtained, methyl 9,10-dihydroxystearate was detected after digestion of methyl 9,10-epoxystearate, and some major volatiles were detected after digestion of linoleate hydroperoxides. Overall, the results showed that significant modifications of dietary oxidized lipids occurred during gastric digestion and supported that the low pH of the gastric fluid played an important role.
目前，人们对膳食脂质氧化化合物在整个胃肠道中发生的化学变化几乎一无所知。由于胃部酸性较强，所以胃部是潜在化学修饰的首个作用部位。在本研究中，具有代表性的膳食氧化化合物被置于体外模拟胃部环境中。因此，亚油酸甲酯氢过氧化物被用作低温和中温食物储存过程中形成的主要氧化化合物的代表。9,10-环氧硬脂酸甲酯、12-氧代硬脂酸甲酯和12-羟基硬脂酸甲酯被选作模型化合物，这些化合物带有在高温油炸形成的氧化化合物中主要存在的含氧官能团。采用气液色谱/火焰离子化检测/质谱联用以及高效液相色谱/紫外检测进行分析。结果发现，9,10-环氧硬脂酸甲酯和亚油酸甲酯氢过氧化物的损失率分别在17.8%至58.8%和42.3%至61.7%之间，而12-氧代硬脂酸甲酯和12-羟基硬脂酸甲酯未发生变化。虽然未获得消化后形成的化合物的定量数据，但在9,10-环氧硬脂酸甲酯消化后检测到了9,10-二羟基硬脂酸甲酯，在亚油酸甲酯氢过氧化物消化后检测到了一些主要挥发性物质。总体而言，结果表明膳食氧化脂质在胃消化过程中发生了显著修饰，并支持胃液的低pH值起到了重要作用。
