The impact of environmental factors on molecular and stable isotope compositions of n-alkanes in Mediterranean extra virgin olive oils

Mihailova, Alīna; Abbado, Dimitri; Kelly, Simon; Pedentchouk, Nikolai

doi:10.1016/j.foodchem.2014.10.003

Cited by 29 publications

(24 citation statements)

References 26 publications

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“…Olive oils are complex matrices with high chemical variability due to genetic and changing environmental factors, different states of ripening of the fruit, ages, different ways of harvesting and extraction prepared with different varieties of different geographical origins resulting in different organoleptic properties and different chemical patterns . Thus, each olive oil has its unique fingerprint characterized by changing contents and types of metabolites such as FA and triacylglycerols (TAG), sterols, n ‐alkanes, volatile compounds, carotinoides, tocopherols, or stable isotopes . Especially, the possibilities of the variations in the FA pattern and their combination in TAG molecules lead to enormous complexity in all vegetable fats and oils.…”

Section: Introductionmentioning

confidence: 99%

A Systematic Chemometric Approach to Identify the Geographical Origin of Olive Oils

Gertz¹,

Gertz²,

Matthäus

et al. 2019

Euro J Lipid Sci & Tech

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The verification of the geographical origin of olive oils by analytical techniques is still a challenge. The goal of this work is to explore the application and accuracy of different chemometric tools combined with near infrared spectroscopy (NIR) based analytical methods in the field of geographical authenticity of olive oils. As olive oils associated with different geographical origins are mainly characterized by different fatty acid (FA) and triacylglycerol (TAG) compositions, NIR methods for the fast and reliable determination of these parameters are developed. Next, these NIR methods are used to characterize a comprehensive set of olive oils (n > 5000) derived from 19 different countries. This set of data is used to build a statistical workflow, which allows the determination of the geographical origin of unknown olive oil samples. First of all, the untreated data set is pretreated by k‐means clustering and the selection of the relevant analytical variables by principal component analysis (PCA) and linear discriminant analysis (LDA) and min/max normalization of all parameters. Subsequently, classification is performed with a reduced sample set of the 200 most similar samples identified by k‐nearest neighbor tool (kNN). For classification purpose kNN, LDA, naïve Bayes classifier, and logit regression are applied. Practical Applications: The established statistical workflow can be used to verify the geographical origin of olive oils. The application and usage of up to four different statistical models for classification purpose results in a superior probability of the predicted origin in comparison to the application of only one single statistical classification test. As standardized methods are used as reference methods for building the NIR methods, the FA and TAG composition and the iodine value can be either determined by the standard methods or by the described NIR method. The presented statistical approach will help to build up a system for the verification of the geographical origin of olive oils.

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Section: Introductionmentioning

confidence: 99%

A Systematic Chemometric Approach to Identify the Geographical Origin of Olive Oils

Gertz¹,

Gertz²,

Matthäus

et al. 2019

Euro J Lipid Sci & Tech

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“…The n -alkane composition and concentrations are not likely to change during washing, handling, or transport, due to their hydrophobic nature. Previous research has shown that molecular distributions of n -alkanes can be used to determine the geographical origin of plant-based products, for example, for assessing the quality and authenticity of olive oils [ 10 – 12 ]. These studies indicated it was possible, using the n -alkane pattern and composition, to distinguish between crude and refined oils of different plants and geographical origins.…”

Section: Introductionmentioning

confidence: 99%

Determination of n-alkanes in C. annuum (bell pepper) fruit and seed using GC-MS: comparison of extraction methods and application to samples of different geographical origin

et al. 2015

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An efficient extraction and analysis method was developed for the isolation and quantification of n-alkanes from bell peppers of different geographical locations. Five extraction techniques, i.e., accelerated solvent extraction (ASE), ball mill extraction, ultrasonication, rinsing, and shaking, were quantitatively compared using gas chromatography coupled to mass spectrometry (GC-MS). Rinsing of the surface wax layer of freeze-dried bell peppers with chloroform proved to be a relatively quick and easy method to efficiently extract the main n-alkanes C27, C29, C31, and C33. A combined cleanup and fractionation approach on Teflon-coated silica SPE columns resulted in clean chromatograms and gave reproducible results (recoveries 90–95 %). The GC-MS method was reproducible (R2 = 0.994–0.997, peak area standard deviation = 2–5 %) and sensitive (LODs, S/N = 3, 0.05–0.15 ng/μL). The total main n-alkane concentrations were in the range of 5–50 μg/g dry weight. Seed extractions resulted in much lower total amounts of extracted n-alkanes compared to flesh and surface extractions, demonstrating the need for further improvement of pre-concentration and cleanup. The method was applied to 131 pepper samples from four different countries, and by using the relative n-alkane concentration ratios, Dutch peppers could be discriminated from those of the other countries, with the exception of peppers from the same cultivar.Graphical AbstractProcedure for pepper origin determination

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“…n ‐C 15 Alkane (Sigma–Aldrich) was used as an internal standard (concentration 1.92 mg/L) and added to the olive oil/hexane solution. n ‐Alkanes were separated from the oil/hexane mixture using column chromatography as described in our previous study .…”

Section: Methodsmentioning

confidence: 99%

“…GC was performed using HP Agilent 7820A Gas Chromatograph (Agilent Technologies, Inc., Wilmington, USA) with a flame ionisation detector (FID) following the protocol described in our previous work . n ‐Alkane average chain length (ACL) was determined using peak areas for n ‐C 21 to n ‐C 35 alkanes according to the following formula:

ACL = \frac{(21 A_{21}) + (22 A_{22}) + \dots + (35 A_{35})}{(A_{21} + A_{22} + A_{23} + \dots + A_{35})}

where A x corresponds to n ‐alkane peak area.…”

Section: Methodsmentioning

confidence: 99%

Differences in n‐alkane profiles between olives and olive leaves as potential indicators for the assessment of olive leaf presence in virgin olive oils

Mihailova

Abbado²,

Pedentchouk

2015

Euro J Lipid Sci & Tech

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The olive (Olea europaea) is one of the most important crops in the Mediterranean region for economic and culinary reasons. Cuticular waxes coat olives and olive leaves and play a significant role in plant physiology and resistance against environmental stresses. The present study describes n-alkane profiles in cuticular waxes of olives and leaves of three Italian varieties (Frantoio, Leccino and Maraiolo) during different stages of olive development. Additionally, the study investigates the differences between n-alkane profiles of extra virgin olive oils with low and high leaf content. Olive leaves are characterised by the predominance of n-alkanes with longer carbon chains (n-C 29 -C 33 ) compared with olives (n-C 25 -C 29 ). During all stages of olive ripening period, n-alkane average chain length (ACL) values of olive leaves are significantly higher compared with those of olives. Extra virgin olive oils with admixture of leaves have significantly different n-alkane profiles than those free from leaf material. Practical applications:The results of this study will contribute significantly to the currently very limited information on n-alkane data from olive tree varieties used for oil production. The presence of leaves increases the concentrations of long chain n-alkanes (n-C 31 -C 35 ) in extra virgin olive oils, therefore studying the differences between n-alkane profiles of olives and olive leaves could help establishing the presence of leaf material in produced extra virgin olive oils. Information about the relative and absolute concentrations of n-alkanes in olives, olive leaves and olive oil will also be useful for biochemical and metabolic studies of the olive tree.

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The impact of environmental factors on molecular and stable isotope compositions of n-alkanes in Mediterranean extra virgin olive oils

Cited by 29 publications

References 26 publications

A Systematic Chemometric Approach to Identify the Geographical Origin of Olive Oils

A Systematic Chemometric Approach to Identify the Geographical Origin of Olive Oils

Determination of n-alkanes in C. annuum (bell pepper) fruit and seed using GC-MS: comparison of extraction methods and application to samples of different geographical origin

Differences in n‐alkane profiles between olives and olive leaves as potential indicators for the assessment of olive leaf presence in virgin olive oils

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