Effect of olive polyphenols on lipid oxidation of high-fat beef during digestion

Olive oil is one of the most important ingredients in the Mediterranean diet, in which its polyphenols adversely affect dietary lipid oxidation. In this study, the effect of olive oil polyphenols on lipid oxidation of high-fat beef during digestion was determined. Thirty-three phenolic compounds were tentatively identified, and the contents of 3,4-dihydroxyphenylethanol-elenolic acid dialdehyde (3,4-DHPEA-EDA), 3,4-dihydroxyphenylethanol-elenolic acid (3,4-DHPEA-EA), p-hydroxyphenylethanol elenolic acid (p-HPEA-EA) and hydroxytyrosol were higher than those of other compounds. In an in vitro model, the production of lipid oxidation products, including hydroperoxides, malondialdehyde, 4-hydroxy-2-hexenal and 4-hydroxy-2-nominal, were significantly inhibited by olive polyphenol in the gastrointestinal digests. Compared with the other four groups, the inhibition was better when the polyphenol content reached 600 mg GAE/kg. The 3,4-DHPEA-EDA and 3,4-DHPEA-EA played a better antioxidant role in the stomach stage, while hydroxytyrosol showed the more potent antioxidant activity in the intestinal phase. Electron spin resonance technology showed that two main free radicals, including alkyl radical and alkoxy radical, were detected during the high-fat beef digestion, and olive polyphenols could significantly reduce their formation. All these results showed that the lipid oxidation could be significantly inhibited by olive oil with higher polyphenol content, indicating that the consumption of olive oil with abundant levels of polyphenols could reduce lipid oxidation of high-fat meat during digestion.