Low vs high field ¹ h Nmr spectroscopy for the detection of adulteration of cold pressed rapeseed oil with refined oils

Cold pressed rapeseed oil (CPRO)is a relatively recent development in rapeseed processing, which produces a quality product with a high market value. High field NMR (400 MHz)is a well-established tool in food analysis, while low-field NMR (60 MHz)is much less studied. This study aims to establish the effectiveness of both techniques in identifying binary adulteration in CPRO. Three adulteration scenarios were investigated: a)CPRO and refined rapeseed oil (RRO); b)CPRO and refined sunflower oil (RSO); and c)CPRO and RRO or RSO. A range of classification techniques were trialled as well as partial least squares regression to gauge predictive quantification performance. The 400 MHz NMR achieved classification rates of 100% in the scenarios with a single adulterant, and 93% in the multiple adulterant scenario. The 60 MHz NMR produced lower but still encouraging classification rates (RSO 92%; RRO 85%; both RRO and RSO 87%).