Quantitative C-13 NMR method using the DEPT pulse sequence for the determination of the geographical origin (DOP) of olive oils

Nuclear magnetic resonance (NMR) spectroscopy is applied to measure the hig h-field (500 MHz) C-13 spectra at natural abundance in olive oil samples in order to ascertain the suitability of NMR for discriminating oils from dif ferent Italian geographical areas of production and, in particular, from ar eas labelled with the 'Denomination of Protected Origin' (DOP). The NMR met hodology, which uses the distortionless enhancement by polarization transfe r (DEPT) pulse sequence for improving the signal-to-noise ratio of C-13 spe ctra, is optimized for the acquisition, processing and integration paramete rs to validate the quantitative measurements of the intensities of C-13 res onances of the whole olive oil spectrum. Principal components analysis, whi ch is applied to the C-13 intensity data, correlates the oil samples from t he same geographical area provided the composition of the olive oil is mono varietal. The correlation is obtained from properties related to the fatty acid composition of the triglyceride fraction of olive oils. Copyright (C) 2001 John Wiley & Sons, Ltd.