Restored Intensities from Customized Crops of NMR Experiments (RICC-NMR) to Gain Better Insight on Chemometrics of Sicilian and Sardinian Extra Virgin Olive Oils

The paper describes the application of mono-dimensional high-resolution nuclear magnetic resonance (NMR) spectroscopy to extra virgin olive oil (EVOO) samples to extract the chemical composition reasonably featured by specific genotype (<i>cultivar</i>) and detailed environmental conditions (<i>terroir</i>). To achieve this goal, we designed a suitable spectroscopic protocol made up of four NMR experiments: (I) standard ¹H{¹³C}, (II) multiple pre-saturated ¹H{¹³C}, (III) ¹H selective excitation at 9.25 ppm, and (IV) ¹³C{¹H} acquisition. The three ¹H-NMR experiments (I-III) were merged into a single informative ¹H-NMR trace. This "Restored Intensities from Customized Crops" (RICC-NMR) allowed us to extract, in just one ¹H-NMR dataset, combined information about (a) main components, (b) less-represented components, and (c) minor but key-ruling secoiridoid species, respectively. Selected integrations of the RICC-NMR trace, together with selected integrations gathered from the ¹³C-NMR profile, led, for each sample, to the quantification of variables able to sort out distinct EVOOs. In this paper, this original methodology was applied to rationalize eighteen EVOOs from Sicily and nineteen from Sardinia, which were chemometrically compared and discussed.