Abstract
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.
Highlights
Lipid oxidation products have attracted much attention because of the wide variety of degenerative processes and diseases associated, including cardiovascular disease, cancer and chronic inflammatory diseases [1,2,3]
Still practically unknown is the contribution of lipid oxidation compounds coming from the diet and those formed endogenously
The objective of this study was to analyze some of the main chemical changes occurring to model lipid oxidation compounds due to simulated gastric digestion
Summary
Lipid oxidation products have attracted much attention because of the wide variety of degenerative processes and diseases associated, including cardiovascular disease, cancer and chronic inflammatory diseases [1,2,3]. In the last few years, a number of reports have shown that lipid oxidation can occur under gastrointestinal conditions. In this regard, Kanner and coworkers described for the first time the stomach as a “bioreactor” in which oxidation and antioxidation reactions take place [4]. Kanner and coworkers described for the first time the stomach as a “bioreactor” in which oxidation and antioxidation reactions take place [4] They carried out interesting in vitro experiments using simulated or human gastric fluids [1,5,6,7,8]. In other studies, using an in vitro static gastrointestinal digestion model, and proton nuclear magnetic resonance spectroscopy and solid phase microextraction-gas chromatography/mass spectrometry for analyses, several kinds of primary and secondary
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