Extra virgin (EV) and ordinary (ON) olive oils: distinction and detection of adulteration (EV with ON) as determined by direct infusion electrospray ionization mass spectrometry and chemometric approaches

Abstract

Extra virgin (EV), the finest and most expensive among all the olive oil grades, is often adulterated by the cheapest and lowest quality ordinary (ON) olive oil. A new methodology is described herein that provides a simple, rapid, and accurate way not only to detect such type of adulteration, but also to distinguish between these olive oil grades (EV and ON). This approach is based on the application of direct infusion electrospray ionization mass spectrometry in the positive ion mode, ESI(+)-MS, followed by the treatment of the MS data via exploratory statistical approaches, PCA (principal component analysis) and HCA (hierarchical clustering analysis). Ten distinct brands of each EV and ON olive oil, acquired at local stores, were analyzed by ESI(+)-MS and the results from HCA and PCA clearly indicated the formation of two distinct groups related to these two categories. For the adulteration study, one brand of each olive oil grade (EV and ON) was selected. The counterfeit samples (a total of 20) were then prepared by adding assorted proportions, from 1 to 20% w/w, with increments of 1% w/w, of the ON to the EV olive oil. The PCA and HCA methodologies, applied to the ESI(+)-MS data from the counterfeit (20) and authentic (10) EV samples, were able to readily detect adulteration, even at levels as low as 1% w/w.

QA: Fraud Control for Foods and Other Biomaterials by Product Fingerprinting

“…This adulteration is difficult to detect at levels below 20% by conventional methods due to the compositional similarity between the two oils. Similarly, PCA and HCA methodologies, applied to the ESI(+)-MS data were able to readily detect adulteration of EVOO with ordinary olive oils, at levels as low as 1% w/w [11]. Mono-, di-and triglycerides together with vitamins and antioxidants were detected and quantified with this method.…”

Electron Impact–Mass Spectrometry Fingerprinting and Chemometrics for Rapid Assessment of Authenticity of Edible Oils Based on Fatty Acid Profiling

“…These steps are presented as a dendrogram which represents the similarity clustering between samples. The method is defined as hierarchical since once two cases are joined in a cluster they remain joined (Alves et al 2010). The HCA clustering plot (dendrogram) is presented in Fig.…”

“…Remarkable efforts have been invested in developing experimentally simple, rapid, accurate, and cost-effective analytical methods for the authentication of edible oils (Catharino et al 2005;Alves et al 2010). More recently, numerous spectroscopic methods based on Fourier transform infrared spectroscopy (FTIR) (Luna et al 2013;Gouvinhas et al 2015;Georgouli et al 2017), near infrared (NIR) (Yang and Irudayaraj 2001;Mendes et al 2015), nuclear magnetic resonance (NMR) (Gouilleux et al 2018;Sani et al 2018;Zhang et al 2018), Raman (Teresa et al 2017; Yildiz Tiryaki and Ayvaz 2017), and fluorescence (Tan et al 2017;Durán et al 2018) techniques combined with multivariate analysis have fabricated good results, though the fingerprint spectra cannot be resolved into individual mass numbers or compounds (Goodacre et al 2002;Wu et al 2004;Eide and Zahlsen 2005).…”

“…Moreover, most of the reported methodologies require hazardous chemical usage (Catharino et al 2005;Eide and Zahlsen 2005;Alves et al 2013;Ng et al 2018). To eliminate these disadvantaged fingerprint analyses, recently, there has been a great of interest in the use of soft or hard ionization MS methods based on matrix-assisted laser desorption ionization (MALDI), electrospray ionization (ESI), or electron impact (EI) ionization for the authentication and adulteration of various food analyses (Wu et al 2004;Thurnhofer and Vetter 2005;Alves et al 2010;Yang et al 2013).…”

“…Several studies have reported the employment of EI-MS to obtain fingerprints of many types of food samples such as potato tubers (Roessner et al 2000), meat (Mottier et al 2000), vegetable oils (Vichi et al 2003;Thurnhofer and Vetter 2005;Yang et al 2013), cereal-based foods (Pittet et al 2004), and honey samples (Rissato et al 2007). Thanks to the several advantages and the omission of chromatographic separation, the mass fingerprinting methodology by using different ionization techniques has been also applied for rapid detection of crude oil or vegetable oil adulteration, after dilution of triglycerides or sterols and extraction of phenolic compounds and fatty acids (FAs) (Goodacre et al 2002;Catharino et al 2005;Alves et al 2010).…”