A rapid NMR-based approach for the direct determination of lipid oxidation metabolites in dry fermented cured Italian sausages containing α-tocopherol

Abstract

The research investigates and demonstrates the potential of the high resolution NMR analysis as a powerful, simple and rapid analytical method to study the extent of lipid oxidation in Italian dry-cured pork sausages containing α-tocopherol. The inclusion of this natural antioxidant additive in the meat products case of study, at levels of 40 mg/Kg and during the manufacturing, considerably increased the resistance to oxidative processes of the total lipid fraction. The effects of adding the natural antioxidant on the lipid oxidation was investigated by proton high-resolution nuclear magnetic resonance (1H HR-NMR) spectroscopy, in dry-cured sausages during storage under vacuum, at 4 °C for 160 days. Higher inhibition of lipid oxidation was observed on the basis of the determination of fatty acid acyl chain profiles in total lipid extracts (TLEs) obtained from sausages, according to a well-known model previously published. In particular, profiles of primary and secondary lipid oxidation products were established, and related to the variation of n-3 fatty acid acyl chains. Lowering of the initial amount of α-tocopherol was also observed on the basis of the variation of the intensities of detectable peaks generated by the resonances of protons present in the molecular structure of the natural antioxidant. The collected results demonstrated the enormous potential of the 1H HR-NMR spectroscopy in investigating the chemical composition of lipids as a meat product shelf-life parameter. Moreover, the findings showed that the application of the selected amount of α-tocopherol was sufficient to decrease lipid oxidation in dry-cured pork sausages, confirming the known properties of this natural antioxidant as a curing agent, as already proved by its use in other different series of fresh and dry-cured chicken sausages, pork salami and fish meat products, especially if fermentation with a nitrate-reducing starter culture is desired