Fatty acid composition and δ13C isotopic ratio characterisation of pumpkin seed oil

This study aimed to verify the authenticity and geographical origin of pumpkin seed oil using chemical analysis by gas chromatography (GC) and isotopic characterisation by gas chromatography combustion stable isotope ratio mass spectrometry (GC/C/IRMS) combined with chemometric analysis. Thirty-eight pumpkin seed samples from various parts of the world were collected and authentic oils were prepared. Pumpkin seed oils are highly unsaturated, oleic acid varies from 26.8 to 43.6% and the content of linoleic acid is between 37.2 and 54.9%. The average delta C-13 values of the main fatty acids are -29.2 +/- 1.2 parts per thousand, -30.3 +/- 1.6 parts per thousand, -27.9 +/- 1.7 parts per thousand and -28.1 +/- 1.7 parts per thousand. for C-16:0, C-18:0, C-18:1, C-18:2, respectively. To determine adulteration, rapeseed, sunflower and soybean oil, were added to pumpkin seed oil in varying percentages (1-10%). A 100% correct classification of both geographical and botanical origin was achieved based on the composition and delta C-13 values of fatty acids. Principal component analysis (PCA) and regularised discriminant analysis (RDA) analysis gave comparable results. (C) 2016 Elsevier Inc. All rights reserved.