Environmental pollution, agricultural practices, climate change, and the various stages of edible oil production are responsible for oil contamination with various chemicals. Among vegetable fats, ...olive pomace oils (OPOs) have higher polycyclic aromatic hydrocarbon (PAH) contents, exceeding the limits in some cases. Several methods for the determination of PAHs in animal and vegetable fats and oils have been published over the years, but they have often failed to eliminate matrix-specific interferences in OPO. The few methods proposed or applied for the specific analysis of PAHs in OPO over the past 20 years are mainly based on two different analytical approaches, namely liquid chromatography-fluorescence detector (LC-FLD) and gas chromatography-mass spectrometry (GC–MS). In the case of the LC-FLD approaches, liquid–liquid extraction with appropriate solvents and one or more purification steps on stationary phases of different compositions are performed. In the case of GC techniques, on the other hand, the most commonly used sample preparation is liquid–liquid partitioning. Due to widespread public concern about PAH contamination, several studies have been conducted to explore ways to mitigate the presence of PAHs in OPOs (i.e., refining processes).
The potential of endogenous
-alkane profiling for the assessment of extra virgin olive oils (EVOO) adulteration (blends with cheaper vegetable oils) has been studied by relatively few authors. ...Analytical methods used for this purpose often involve tedious and solvent-intensive sample preparation prior to analytical determination, making them unattractive. A rapid and solvent-sparing offline solid phase extraction (SPE) gas chromatography (GC) flame ionization detection (FID) method for the determination of endogenous
-alkanes in vegetable oils was, therefore, optimized and validated. The optimized method demonstrated good performance characteristics in terms of linearity (R
> 0.999), recovery (on average 94%), and repeatability (residual standard deviation, RSD < 11.9%). The results were comparable to those obtained with online high-performance liquid chromatography (HPLC)-GC- FID ( RSD < 5.1%). As an example of an application to prove the potentiality of endogenous
-alkanes in revealing frauds, the data set obtained from 16 EVOO, 9 avocado oils (AVO), and 13 sunflower oils (SFO), purchased from the market, was subjected to statistical analysis and principal component analysis. Two powerful indices, namely (
-C
+
-C
)/(
-C
+
-C
) and
-C
/
-C
, were found to reveal the addition of 2% SFO in EVOO and 5% AVO in EVOO, respectively. Further studies are needed to confirm the validity of these promising indices.
Pressurized liquid extraction (PLE) is considered an advanced extraction technique developed in the mid-1990s with the aim of saving time and reducing solvent with respect to traditional extraction ...processes. It is commonly used with solid and semi-solid samples and employs solvent extraction at elevated temperatures and pressures, always below the respective critical points, to maintain the solvent in a liquid state throughout the extraction procedure. The use of these particular pressure and temperature conditions changes the physicochemical properties of the extraction solvent, allowing easier and deeper penetration into the matrix to be extracted. Furthermore, the possibility to combine the extraction and clean-up steps by including a layer of an adsorbent retaining interfering compounds directly in the PLE extraction cells makes this technique extremely versatile and selective. After providing a background on the PLE technique and parameters to be optimized, the present review focuses on recent applications (published in the past 10 years) in the field of food contaminants. In particular, applications related to the extraction of environmental and processing contaminants, pesticides, residues of veterinary drugs, mycotoxins, parabens, ethyl carbamate, and fatty acid esters of 3-monochloro-1,2-propanediol and 2-monochloro-1,3-propanediol from different food matrices were considered.
Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental and processing contaminants generated by both spontaneous and anthropogenic incomplete combustion processes of organic matter. ...Contamination of PAHs in vegetable oils can result from several factors and processes, including environmental contamination, oil processing, and migration from food contact materials. The determination of PAHs in edible oil presents a challenge because of the complexity of the matrix. Since PAHs are present at lower levels than triglycerides, it is necessary to isolate the compounds of interest from the rest of the matrix. To this purpose, a new purification approach based on a double solid-phase extraction (SPE) step followed by high performance liquid chromatography–fluorometric detector (HPLC-FLD) analysis was developed. The method involves a first purification step by using a 5 g silica SPE cartridge, previously washed with dichloromethane (20 mL), dried completely, and then conditioned with n-hexane (20 mL). The triglycerides are retained by the silica, while the PAH-containing fraction is eluted with a mixture of n-hexane/dichloromethane (70/30, v/v). After evaporation, the residue is loaded on a 5 g amino SPE cartridge and eluted with n-hexane/toluene (70/30, v/v) before HPLC-FLD analysis. The focus was the evaluation of the contribution of the various phases of the pomace oil supply chain in terms of the heavy PAHs (PAH8) concentration. Data collected showed that pomace contamination increased (by 15 times) as storage time increased. In addition, the process of pomace drying, which is necessary to reduce its moisture content before solvent extraction of the residual oil, appeared to significantly contribute to the total heavy PAHs content, with increases in value by up to 75 times.
•MOSH and MOAH determination in cereal-based products.•Microwave assisted saponification and extraction followed by on-line LC–GC.•Method performance and recovery tests on different ...matrices.•Comparison with other extraction methods.•Applications to dry pasta, bread, biscuits and cakes.
A high throughput, high-sensitivity procedure, involving simultaneous microwave-assisted extraction (MAS) and unsaponifiable extraction, followed by on-line liquid chromatography (LC)–gas chromatography (GC), has been optimised for rapid and efficient extraction and analytical determination of mineral oil saturated hydrocarbons (MOSH) and mineral oil aromatic hydrocarbons (MOAH) in cereal-based products of different composition. MAS has the advantage of eliminating fat before LC–GC analysis, allowing an increase in the amount of sample extract injected, and hence in sensitivity. The proposed method gave practically quantitative recoveries and good repeatability. Among the different cereal-based products analysed (dry semolina and egg pasta, bread, biscuits, and cakes), egg pasta packed in direct contact with recycled paperboard had on average the highest total MOSH level (15.9mgkg−1), followed by cakes (10.4mgkg−1) and bread (7.5mgkg−1). About 50% of the pasta and bread samples and 20% of the biscuits and cake samples had detectable MOAH amounts. The highest concentrations were found in an egg pasta in direct contact with recycled paperboard (3.6mgkg−1) and in a milk bread (3.6mgkg−1).
•Validation of the fully integrated LC-GC × GC-ToFMS/FID platform.•MOSH and MOAH quantification.•Interlaboratory comparisons on mineral oil in infant formula and vegetable oils.•Reduction of the ...variability during the integration and interpretation steps.
Mineral oils, classified into two main fractions, namely saturated (MOSH) and aromatic hydrocarbons (MOAH), originate from petroleum. Their determination in food is challenging due to the difficulty of isolating them from the matrix and the presence of natural interferences, leading to low reproducibility of the results among different laboratories. Therefore, standardized procedures are highly required to minimize the uncertainty caused by various sources (e.g., integration, interference removal, etc.). However, at present, a few sample preparation procedures have been standardized, while the analytical determination is mainly performed using the hyphenated liquid-gas chromatographic technique coupled with a flame ionization detector (LC-GC-FID). However, LC-GC-FID is still not enough for confirmatory purposes, for which the use of comprehensive 2D GC (GC × GC) has been suggested. Recently, the use of a fully integrated platform for routine and confirmatory purposes has been proposed by Bauwens and co-workers (2022), namely LC-GC × GC-time-of-flight mass spectrometer (ToFMS)/FID.
The aim of this work is to validate the quantification of MOSH and MOAH performed by LC-GC × GC-FID supported by the use of a recently developed integration software. The validation was performed by taking advantage of the participation in several recently organized interlaboratory comparisons organized by the Joint Research Center (to harmonize and validate the method for the determination of MOAH in infant formula products) and by the German Society for Fat Science and the French Technical Institute for the Study and Research of Fats (to improve the standardized European method for MOSH and MOAH in fats, i.e. EN 16995:2017). Data obtained by using LC-GC × GC-FID were in good agreement with those from the ILCs, in terms of recovery, precision, accuracy, and repeatability.
Waxes and fatty acid alkyl esters are minor components used as official parameters to control the authenticity and quality of a high‐value olive oil product. A poor measurement can lead to a ...misleading classification of the oil. The official method requires their analysis together by capillary gas chromatography equipped with a flame ionization detector and an on‐column injector to avoid discrimination and thermal degradation. The degradation can occur to a different extent if different (and not properly optimized) injectors are used. However, other injection techniques, such as programmed‐temperature vaporizer, are much more versatile and more widespread. The aim of the present work was to compare the performance of a programmed‐temperature vaporizer injector, in on‐column and splitless mode, with the on‐column injector to analyze alkyl esters and waxes. Discrimination among high‐boiling compounds was evaluated, as well as the occurrence of thermal degradation, especially of sterols and diterpene alcohol (phytyl and geranylgeraniol) esters. A proper optimization of a programmed‐temperature vaporizer injection, with particular attention to the liner selection, was proven to provide comparable results to the traditional on‐column injection. A performance comparison was carried out both on standard mixtures and on real oil samples.
The authenticity of coffee beans was addressed in this study using an analytical method with minimal sample preparation to achieve simple oil extraction and through the implementation of ...cost-effective equipment. For this purpose, methods using UHPLC with CAD and FLD detectors were applied to detect triglycerides and tocopherols in coffee, respectively. The coffee samples included two main varieties: Arabica from Brazil, Colombia, Ethiopia, and Uganda, as well as the Robusta variety from Cambodia, Guatemala, India, and Vietnam. The samples were either in their green state or subjected to different roasting levels. The used methods successfully distinguished the Arabica and Robusta variants targeted in this study based on their tocopherols and TAG profiles, with the latter being particularly effective for discriminating the origins of the Arabica coffee, while tocopherols excelled at differentiating the origin of the Robusta coffee. TAGs and tocopherols were not affected by the type of roasting, from medium to very dark, suggesting it is possible to distinguish between coffee varieties independently from their degree of roasting. The obtained results hold valuable implications for future research regarding coffee fraud and authenticity.
The present investigation deals with a method improvement to increase data throughput and reduce solvent consumption for both saturated and aromatic mineral oil hydrocarbon determination using a ...coupled liquid–gas chromatographic system. The starting point of this work was the method proposed by Biedermann, Fiselier, and Grob in 2009. A total time and solvent reduction of 34 and 23%, respectively, was obtained by speeding up the GC run and reducing the LC‐reconditioning step. The band broadening, occurring in the LC column during stop‐flow in the multitransfer mode, was assessed by comparing the variances of the perylene peak width recorded in the stop‐flow and normal modes. Band broadening directly proportional to the stop time of the LC pumps was observed, however, it did not affect the analytical reliability. A series of real samples (paperboards and pasta) was analyzed obtaining comparable results using both the reference and proposed method, both in the normal and multitransfer modes.
The effect of ultrasound (20 kHz, 153 μm) on the prefermentation extraction mechanisms in Sauvignon Blanc grapes was studied, focusing on 3-mercaptohexan-1-ol (3MH) and ...4-mercapto-4-methyl-pentan-2-one (4MMP) precursors linked to glutathione (GSH) and cysteine (Cys). The treatment determined a positive extraction trend between the duration (untreated, 3 and 5 min) and the conductivity or the concentration of catechins and total phenols, significantly differentiated after 5 min. Nevertheless, the concentration of the thiol precursors in grape juice not only remained undifferentiated, but that of 3-S-glutathionyl mercaptohexan-1-ol showed a negative trend with the treatment time applied (168 ± 43, 156 ± 36, and 149 ± 32 μg/L, respectively, for control, 3 and 5 min). The divergence on the effect between families of compounds suggests an interaction between the sonication treatment and thiol precursor molecules. In order to evaluate the possible degradation properly, ultrasound was applied in a model solution spiked with 3MH and 4MMP precursors, reproducing the conditions of grapes. Except for Cys-3MH, the mean concentration (
= 5) for the rest of the precursors was significantly lower in treated samples, predominantly in those linked to glutathione (~-22% and ~18% for GSH-3MH and GSH-4MMP) rather than to cysteine (~-6%~-8% for Cys-3MH and Cys-4MMP). The degradation of precursors was associated with a significant increase of 3MH and 4MMP. The formation of volatile thiols following sonication is interesting from a technological point of view, as they are key aroma compounds of wine and potentially exploitable in the wine industry through specific vinification protocols.
PDF