Phenolic compounds can limit the nitrosation of secondary amines in a cooked ham model

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Nitrite is a common additive in cured meat formulation that provides microbiological safety, lipid oxidation management and typical organoleptic properties. However, nitrite is also associated with the formation of nitrosamines, some of them being genotoxic and associated with colon carcinogenesis. Nitrite addition is thus pointed at and mechanisms leading to nitroso-compounds formation should be elucidated before establishing strategies to control those reactions during meat processing and digestion. The first aim of this study was to evaluate the anti-nitrosative capacity of phenolic compounds (PC) selected among various phenolic classes representing plant diversity. Commercially-available plant extracts rich in the most anti-nitrosative PC were then evaluated. Mechanisms underlying the PC anti-nitrosative capacity will also be discussed. We designed an anti-nitrosative test using N-acetyltryptophan (AcTRP) as a marker in an oil/water emulsion model. The model was studied at pH 5 to simulate secondary amine nitrosation during product storage and beginning of the digestion and at pH 2.5 in order to mimic the end of gastric digestion. Concentrations in AcTRP, sodium nitrite, myoglobin, free iron, and lipids were as in ham. AcTRP nitrosation and PC metabolisation were followed by UPLC-DAD-MS. In the absence of PC, AcTRP nitrosation was found to be three-fold higher at pH 2.5 compared to pH 5 suggesting that the pH decrease occurring during gastric digestion can favor secondary amine nitrosation. Additionally, all the PC tested except naringin were able to limit NO-AcTRP formation at pH 2.5 and 5. The anti-nitrosative effect of PC decreased in the same following order for both pH: caffeic acid > epicatechin > chlorogenic acid ≈ rutin. Ascorbic acid showed the strongest effect at pH 5 but no effect at pH 2.5. Plant extracts from green tea leaves, rosemary, olive among others and dehydrated juices (acerola…) proved to be anti-nitrosative at pH 5, suggesting that, even when involved in a complex matrix, PC could limit NO-AcTRP formation. Last, UPLC-DAD-MS analyses highlighted the ability of PC to react with nitrite undergoing C-nitration, C-nitrosation and oxidation. Thus, PC are able to scavenge part of the nitrite thus reducing residual nitrite available for N-nitrosation of AcTRP. This major finding suggests that some plant extracts rich in PC could be used as additives to reduce nitrosamine formation during cured meat processing, storage and digestion.