1H-NMR fingerprinting to evaluate the stability of olive oil

1H-NMR fingerprinting is used to evaluate the stability of olive oil at room temperature while protected from light. Principal component analysis (PCA) of the 1H-NMR spectral data allows to visualize the evolution of virgin olive oil (VOO) with time. The PCA loadings disclose the chemical compounds responsible for the compositional changes taking place in VOO. None of the 1H-NMR signals present at time zero disappeared or experienced significant decreases or increases within the 3 years and seven months of the study. However, some small changes in the signals, and the appearance of some low intensity ones, indicate that some oxidative and hydrolytic degradation of the VOO started after one year. The presence of 1H-NMR signals of hydroperoxides (primary oxidation products) with relative small intensities indicates that the oxidative degradation was taking place at a very low rate and yield. Moreover, the characteristic resonances of aldehydes (main secondary oxidation products) were not detected in the VOO over the studied time period, therefore the secondary oxidation process had not yet occurred. These results confirm the high oxidative stability of VOO at room temperature. On the other hand, slight changes in the 1H-NMR signal intensity of tryglycerides and sn-1,3-diglycerides indicates that some hydrolytic degradation of the VOO had started.