Determination of saturated aliphatic hydrocarbons in vegetable oils

Optimization of sample clean-up for the determination of small amounts of MOSH and MOAH in edible oils - method DGF C-VI 22 (20)

Methods for determining MOSH and MOAH in edible oils showed major problems with interlaboratory comparability of analytical results, especially in the lower concentration range below 10 mg/kg. However, a method with improved sensitivity and reproducibility is urgently needed to obtain a valid data basis for minimization efforts. To cope this problem a new method was created in 2020. The method was established as the standard method DGF C-VI 22 (20) of the German Society for Fat Science e.V. (DGF). For the development of this method different sample epoxidation approaches have been performed, evaluated and improved. Additionally, a saponification, a decision tree for sample preparation, an upstream clean-up column and a system suitability test were introduced. The focus was on reliability and interlaboratory comparability over all edible oil matrices up to a LOQ of 1 mg/kg. The optimized method was validated in terms of trueness and precision in a collaborative trail with 11 laboratories. The achieved recovery rates of 89-105% MOSH and 70-105% MOAH met the JRC requirements. Method and validation results were obtained with HorRat values between 1.3 and 1.8 for MOSH and MOAH.

The Mineral Oil Hydrocarbon Paradox in Olive Pomace Oils

The aim of this work was to understand the actual content of mineral oil hydrocarbons (MOH) in olive pomace oil in order to contribute to the monitoring requested by EFSA for the food groups making a relevant impact on human background exposure. Such information will complement both the information inferred from the limits established by the EU and the interpretation of the coming toxicological risk assessment. At the same time, the origin of such a group of compounds is discussed. From the raw material to the commercial product, olive pomace oils were sampled and analyzed at different points and/or conditions. Through the ultimate online HPLC-GC-FID system, we gathered information on the MOH concentrations and molecular mass profiles (C-fractions), and through GCxGC-TOF/MS, we identified the key structures that prove the innocuousness of the mineral oil aromatic hydrocarbon (MOAH) fraction. Our approaches provided chromatographic signals on the C10-C50 range, rendering 33-205 mg/kg mineral oil saturated hydrocarbon (MOSH) and 2-55 mg/kg MOAH in the commercial product. The results confirmed that the C25-C35 cut is the main fraction to which humans are exposed via olive pomace oil, showing concentrations highly dependent on the extraction process. Moreover, the identification of the main MOAH groups showed that in olive pomace oil, mainly 1- and 2-ring species were present, being virtually free of the carcinogenic 3-7 ring aromatics.

Offline Solid-Phase Extraction and Separation of Mineral Oil Saturated Hydrocarbons and Mineral Oil Aromatic Hydrocarbons in Edible Oils, and Analysis via GC with a Flame Ionization Detector

A method was developed for the determination of mineral oil saturated hydrocarbons (MOSH) and mineral oil aromatic hydrocarbons (MOAH) in edible oils, achieving similar limits of quantification than those obtained by online extraction methodologies, i.e., 0.5 mg/kg. The isolation of MOSH and MOAH was performed in a silver nitrated silica gel stationary phase prior to their analysis by gas chromatography–flame ionization detector (GC-FID). To improve the sensitivity, the simulated on-column injection method, using a suitable liner, was optimized. The method was validated at 0.5, 10.0 and 17.9 mg/kg, and recoveries ranged from 80 to 110%. Intra and inter-day precision were evaluated at the same levels, and relative standard deviation (RSD) was lower than 20%. The method was applied to a total of 27 samples of different types of oil previously analyzed in an accredited laboratory, detecting MOSH up to 79.2 mg/kg and MOAH up to 22.4 mg/kg.

Occurrence of n-Alkanes in Vegetable Oils and Their Analytical Determination

Vegetable oils contain endogenous linear hydrocarbons, namely n-alkanes, ranging from n-C21 to n-C35, with odd chain lengths prevalent. Different vegetable oils, as well as oils of the same type, but of different variety and provenience, show typical n-alkane patterns, which could be used as a fingerprint to characterize them. In the first part of this review, data on the occurrence of n-alkanes in different vegetable oils (total and predominant n-alkanes) are given, with a focus on obtaining information regarding variety and geographical origin. The second part aims to provide the state of the art on available analytical methods for their determination. In particular, a detailed description of the sample preparation protocols and analytical determination is reported, pointing out the main drawbacks of traditional sample preparation and possible solutions to implement the analysis with the aim to shift toward rapid and solvent-sparing methods.

Chemical composition and oxidative stability of eleven pecan cultivars produced in southern Brazil

Nuts are considered highly nutritious foods and a source of health-promoting compounds. Therefore, the aim of this study was to evaluate the chemical composition (proximate composition, fatty acids, volatile compounds, total phenolics, squalene, and β-sitosterol) of eleven pecan cultivars harvested in Rio Grande do Sul State (Brazil) and investigate their oxidative stability by the Rancimat method. 'Barton' is the main cultivar produced in Brazil and presented the highest protein, linoleic acid, and linolenic acid values and the lowest saturated fatty acid values, which provide health benefits. 'Mahan' showed the highest oxidation induction time, both in extracted oil and ground samples, low abundance of lipid oxidation compounds, low polyunsaturated fatty acids, high levels of oleic acid and β-sitosterol, which suggests potential for storage. 'Stuart' and 'Success' had the highest total dietary fiber values. Moreover, analysis showed that 'Chickasaw' and 'Success' had large quantities of compounds correlated to lipid oxidation, suggesting low stability for long-term storage. These results imply that the physicochemical characteristics and proximate composition of pecan nut cultivars from southern Brazil have variable parameters that may depend on their genetic variability.

Markers of quality and genuineness of commercial extra virgin sacha inchi oils

This work tackles the study of the quality and authenticity of oils labeled and commercialized as extra virgin sacha inchi oil. Major and minor components as triglycerides, fatty acid methyl esters, tocopherols, sterols and hydrocarbons are determined as well as other physicochemical parameters (density, viscosity, acidity and peroxide value). The results showed that some of the commercialized oils do not fulfill the basic requirement established in the regulation such as the content of α-linolenic acid, higher than 44.7 or 55.0% in the cases of P. volubilis and P. huayllabambana, respectively. The calculated stigmasterol/campesterol ratio for genuine sacha inchi oils should be around 4, however not all commercial oils analyzed comply with this requirement. The presence of the flavons sesamin and sesamolin indicates the addition of compounds from sesame oils. Finally, some of the commercial oils showed to contain trans fatty acids although this was not accompanied by the sterene hydrocarbon presence.