Statistical classification of pumpkin seed oils by direct infusion mass spectrometry: Correlation with GC‐FID profiles

Abstract

A method to classify pumpkin seed oils according to their species (Cucurbita maxima, Cucurbita pepo, and Cucurbita moschata), and C. moschata oils according to their genetic variety (RG, Inivit C‐88 and Inivit C‐2000) using fatty acid profiles obtained by direct infusion mass spectrometry (DIMS) has been developed. For DIMS, pumpkin seed oils were 1:4 (v/v) diluted with an 85:15 propanol/methanol (v/v) mixture containing 40 mM ammonia and directly infused into the mass spectrometer using a syringe pump. The establishment of ratios of the peak abundances of the free fatty acids followed by linear discriminant analysis was employed to predict both pumpkin seed oil species and C. moschata genetic variety. Moreover, the profiles obtained with this methodology were compared with the profiles obtained by the traditional GC‐FID. Since a good correlation between both methodologies was obtained, the proposed DIMS method is a promising alternative for fatty acid fingerprinting of pumpkin oils, with the advantage that prior chromatographic separation is not required.Practical applications: Pumpkin seed oils from several species and variety, differing in their organoleptic, antioxidant, and pharmaceutical properties, are found at high prices within the organic farming and gastronomical commercial circuits. Therefore, authentication methods capable of establishing the origin and other quality parameters of pumpkin seed oils are required. In this work, a simple and quick DIMS method, capable of predicting the species and genetic variety of pumpkin seed oils has been developed. The MS intensities of the free fatty acids can be measured after a simple dilution of the oils; in this way, the conventional GC‐FID separation is avoided, being only necessary to rinse the spectrometer for 5 min between successive infusions to achieve low backgrounds and reproducible oil profiles. Thus, the proposed method is a promising alternative to the traditional GC‐FID method for fatty acid fingerprinting, with the additional advantage that previous chromatographic separation is not required.Fatty acid profiles obtained by direct infusion MS were used to predict the species and genetic variety of pumpkin seed oils.