Novel Strategy for the Recognition of Adulterant Vegetable Oils in Essential Oils Commonly Used in Food Industries by Applying ¹³C NMR Spectroscopy

Abstract

Essential oils (EOs) are valuable products commonly employed in the food industry and intensively studied as biopreservatives for the extension of food shelf-life. Unfortunately, EOs might be counterfeit to increase industrial profits. Among the possible adulterants, vegetable oils (VOs) must be considered for their characteristics and low costs. We aimed to apply nuclear magnetic resonance (NMR) spectroscopy for the detection and identification of VOs in mixtures with EOs. This innovative strategy is based on comparing the peak area ratio matrices of characteristic VO 13 C NMR fatty acid signals with those of adulterated EOs. The identification of the VOs was achieved by calculating the matrix similarity at different confidence levels. The strategy demonstrated the capacity to efficiently recognize the presence of adulteration and the type of VO adulterant in mixtures. Thus, the method was applied to 20 commercial EOs, and VOs were detected and then identified in four samples.

A Novel qNMR Application for the Quantification of Vegetable Oils Used as Adulterants in Essential Oils

“…In our previous work, an efficient method for the detection and identification of vegetable oils in mixtures with EOs was developed and validated. The recognizing method was based on the creation of specific chemical fingerprints for the most common vegetable oils, which can be employed as adulterants [ 21 ]. Here, the actual quantification of the adulterant content was attempted by employing qNMR both on proton and carbon spectra.…”

“…All the experiments were performed at 300 K and non-spinning. The assignments of vegetable oils' signals were carried out using standard compounds and by comparison of 1 H-NMR and 13 C-NMR spectra with literature data in our previous work [21].…”

“…In our previous work, the application of 13 C-NMR was attempted for the identification of the vegetable oil used as adulterant in the mixture with EOs. This approach demonstrated to successfully recognize the adulterant in all cases, regardless of the kind of EO employed in the analysis [ 21 ]. Therefore, as a continuation of the previous work, a versatile method was set up for the quantification of vegetable adulterants in EOs.…”

Adulteration of Essential Oils: A Multitask Issue for Quality Control. Three Case Studies: Lavandula angustifolia Mill., Citrus limon (L.) Osbeck and Melaleuca alternifolia (Maiden & Betche) Cheel

“…These methods, however, generally require the use of multivariate statistical elaborations (principal component analysis and independent component analysis) or the building up of artificial neural networks, thus implying a further step of data processing. Very recently, Truzzi et al reported a method based on NMR spectroscopy without a further statistical step not only able to detect the presence of an adulteration with vegetable oils but, also, to identify the added adulterant through its 13 C-NMR fingerprint [ 12 ].…”

“…However, the precise identification of vegetable oil is often difficult due to the signal overlap of similar molecules [ 11 ]. Very recently, Truzzi et al introduced a new method based on 13 C-NMR spectroscopy to recognise adulterant vegetable oils in EO; the method does not require additional data elaboration with a multivariate analysis [ 12 ].…”