Papers by Wenceslao Moreda
Food Additives & Contaminants: Part A, Jan 29, 2016
Olive fruits contain an n-alkane series of saturated hydrocarbons mainly in the pulp. Lower amoun... more Olive fruits contain an n-alkane series of saturated hydrocarbons mainly in the pulp. Lower amounts of a complex mixture of paraffins, unresolved by gas chromatography (UCM), have been found in cuticle, stone (woody shell and seed), olive leaves, and talc used as an aid to olive oil extraction. The amounts of both kinds of hydrocarbons are related to the olive cultivar and are transferred to oils in a proportion depending on the oil obtaining process (centrifugation or solvent extraction). In olive oil obtained by centrifugation only n-alkanes were detected. However in olive oil extracted by second centrifugation, small amounts of UCM paraffins were detected together with the n-alkanes. Olive-pomace oils showed a
Proceedings of the Virtual 2021 AOCS Annual Meeting & Expo, May 3, 2021
Fast and effective analytical screening tools providing new suitable authenticity markers and app... more Fast and effective analytical screening tools providing new suitable authenticity markers and applicable to a large number of samples are required to efficiently control the global olive oil (OO) production, and allow the rapid detection of low levels of adulterants even with fatty acid composition similar to OO. The present study aims to develop authentication models for the comprehensive detection of illegal blends of OO with adulterants including different types of high linoleic (HL) and high oleic (HO) vegetable oils at low concentrations (2-10%) based on shotgun triacylglycerol (TAG) profile obtained by Flow Injection Analysis-Heated Electrospray Ionisation-High Resolution Mass Spectrometry (FIA-HESI-HRMS) at a large-scale experimental design. The sample set covers a large natural variability of both OO and adulterants, resulting in more than one thousand samples analysed. A combined PLS-DA binary modelling based on shotgun TAG profiling proved to be a fit for purpose screening tool in terms of efficiency and applicability. The external validation resulted in the correct classification of the 86.8% of the adulterated samples (diagnostic sensitivity = 0.87), and the 81.1% of the genuine samples (diagnostic specificity = 0.81), with an 85.1% overall correct classification (efficiency = 0.85).
Food Chemistry, Jun 1, 2020
The commercialization of declared blends of olive oil and seed oil is something long approved by ... more The commercialization of declared blends of olive oil and seed oil is something long approved by the European Union. There, the olive oil percentage must be at least 50 % if the producer aims to advertise its presence on the front label, i.e., somewhere other than in the ingredients list. However, the Regulation did not propose any method to verify such proportion. For this purpose, we recommend the use of decisional trees, being the parameters under study those in which the greatest differences between olive and seed oils are shown: triacylglycerols, acyclic saturated hydrocarbons, free sterols, and tocopherols. In this way, to guarantee the presence of olive oil at 50 %: i) palmitodiolein must be above 11-15 %; ii) the ß/γ-tocopherol ratio must be below 2.4; iii) the alkane sum C21-C25 should be higher than 3.5-6 %; and iv) the total sterol content cannot surpass 2400 mg/kg.
Grasas Y Aceites, Jun 30, 2014
Olive Anthracnose and its effect on oil quality. Olive (Olea europaea subsp. europaea var. europa... more Olive Anthracnose and its effect on oil quality. Olive (Olea europaea subsp. europaea var. europaea) is one of the first domesticated and cultivated trees that is widely distributed in the Mediterranean regions. The Anthracnose, caused by the two complex fungal species Colletotrichum acutatum and C. gloeosporioides, is the most important disease adversely affecting the olive oil quality. Even so, the effect of Anthracnose on oil quality is largely unknown and many questions remain unanswered. This offers a unique opportunity to study how Colletotrichum species, cultivars, infection type (latent or visible) and severity, and other factors that may affect different parameters of oil quality, such us acidity, peroxide value, K232, K270, phenolic compounds, or alkyl esters. This review focuses on the current knowledge of the biology, epidemiology, and management of Anthracnose and its effect on olive oil quality.
Food Chemistry, Jun 1, 2012
Long-chain aliphatic aldehydes are natural minor components occurring in the cuticle of numerous ... more Long-chain aliphatic aldehydes are natural minor components occurring in the cuticle of numerous plant species and also evidenced in virgin olive oils. The fraction containing these compounds can be isolated from the oil samples by using a solid-phase extraction silica-gel cartridge and then directly analysed by GC on a 5% diphenyl-95% dimethylsiloxane capillary column, using an on column-injection system. The proposed methodology showed that extra virgin olive oils contain long-chain aliphatic aldehydes, with even carbon-atom numbers from C 22 to C 30. Quantitative results, using the synthesised aldehyde C 21 as internal standard, give concentrations of total long-chain aliphatic aldehydes in a variable range below 116 mg kg-1 , being hexacosanal (C 26-al) the most abundant aldehyde. The different experimental conditions utilized during olive oil extraction processes influence the total aldehydes concentration. Besides contribution to the knowledge of the minor-component composition present in olive oil, their interest and relationship with wax esters, aliphatic alcohols and n-alkanes are discussed.
Grasas Y Aceites, Jun 30, 2000
Olive oil is a key product of our Mediterranean climate. Owing to its chemical composition, it pr... more Olive oil is a key product of our Mediterranean climate. Owing to its chemical composition, it provides excellent health benefits to its consumers. Hence, nowadays, it is of the upmost importance for scientists to determine the factors that influ ence its concentration in beneficial chemical compounds and the extent of their influence. In this investigation the influence of harvesting time and variety of olive oil was studied in terms of phenolic concentration. All varieties were evaluated and opt imal harvest dates were associated for each variety in terms of greatest concentration of beneficial phenolic compounds
Foods, 2021
Minor compounds in vegetable oils are distributed between free and esterified forms, and the rati... more Minor compounds in vegetable oils are distributed between free and esterified forms, and the ratio of these two fractions could represent an important parameter for assessment of oil authenticity. A simple method based on offline SPE-GC-FID for the analysis of free and esterified hydroxylated minor compounds in olive and sunflower oils has been developed and in-house validated. A satisfactory repeatability relative standard deviation (<7.5%) was obtained in all cases. The method, which requires simple instrumentation, allows for reliable quantification in a single chromatographic run with the advantages of minimizing sample manipulation, use of toxic solvents and reagents, and time consumption. The analytical procedure was applied to pure oil samples, including 15 authentic extra virgin olive oils collected from different European countries (Spain, Italy, Greece, and Portugal). Finally, the proposed SPE-GC-FID methodology could detect changes in the ratio between the free and est...
Food Control, 2021
Fast and effective analytical screening tools providing new suitable authenticity markers and app... more Fast and effective analytical screening tools providing new suitable authenticity markers and applicable to a large number of samples are required to efficiently control the global olive oil (OO) production, and allow the rapid detection of low levels of adulterants even with fatty acid composition similar to OO. The present study aims to develop authentication models for the comprehensive detection of illegal blends of OO with adulterants including different types of high linoleic (HL) and high oleic (HO) vegetable oils at low concentrations (2-10%) based on shotgun triacylglycerol (TAG) profile obtained by Flow Injection Analysis-Heated Electrospray Ionisation-High Resolution Mass Spectrometry (FIA-HESI-HRMS) at a large-scale experimental design. The sample set covers a large natural variability of both OO and adulterants, resulting in more than one thousand samples analysed. A combined PLS-DA binary modelling based on shotgun TAG profiling proved to be a fit for purpose screening tool in terms of efficiency and applicability. The external validation resulted in the correct classification of the 86.8% of the adulterated samples (diagnostic sensitivity = 0.87), and the 81.1% of the genuine samples (diagnostic specificity = 0.81), with an 85.1% overall correct classification (efficiency = 0.85).
Grasas y Aceites, 2018
This work aimed to determine the major and minor compounds of avocado oils. Mono-varietal oils fr... more This work aimed to determine the major and minor compounds of avocado oils. Mono-varietal oils from the Bacon, Fuerte, Hass, and Pinkerton cultivars were obtained by means of an Abencor® system, while commercial oils from Brazil, Chile, Ecuador and New Zealand were purchased locally. The content of triacylglycerols, fatty acids, aliphatic and terpenic alcohols, desmethyl- methyl- and dimethyl-sterols, squalene and tocopherols were determined. The main triacylglycerols were those with ECN48. In addition, the oleic, palmitic and linoleic acids prevailed. Desmethyl-sterols were the principal minor compounds. Low amounts of aliphatic and terpenic alcohols were also found. Squalene concentrations were higher in Bacon, Fuerte and Pinkerton oils than in the other oils. The most abundant tocopherol was α-tocopherol. Partial least squares discriminant analysis made it possible to express the differences among the samples. To summarize, this work brings a different approach to the complete ch...
Food Chemistry, 2022
1 H-NMR fingerprinting of edible oils and a set of multivariate classification and regression mod... more 1 H-NMR fingerprinting of edible oils and a set of multivariate classification and regression models organised in a decision tree is proposed as a stepwise strategy to assure the authenticity and traceability of olive oils and their declared blends with other vegetable oils (VOs). Oils of the 'virgin olive oil' and 'olive oil' categories and their mixtures with the most common VOs, i.e. sunflower, high oleic sunflower, hazelnut, avocado, soybean, corn, refined palm olein and desterolized high oleic sunflower oils, were studied. Partial least squares (PLS) discriminant analysis provided stable and robust binary classification models to identify the olive oil type and the VO in the blend. PLS regression afforded models with excellent precisions and acceptable accuracies to determine the percentage of VO in the mixture. The satisfactory performance of this approach, tested with blind samples, confirm its potential to support regulations and control bodies.
Trends in Food Science & Technology, 2019
Background: The physical, chemical and organoleptic characteristics of olive oil (OO) are regulat... more Background: The physical, chemical and organoleptic characteristics of olive oil (OO) are regulated by the European Union (EU) by Reg. (EEC) 2568/91 as amended, which also establishes methods for their analysis. Despite the fact that the OO sector is highly regulated, it is acknowledged that there are still problems; fats and oils, including OOs, are ranked third, after meat and meat products and fish and fish products, in the 2016 EU Food Fraud report on non-compliances per product category. For this reason, EU legislation, among the most advanced in the field, continuously chases after the emerging frauds. The process of proposing new methods or reviewing those current is constantly in progress, to ensure the robustness and the clarity required by official standardised procedures. Scope and approach: This review will identify current gaps in EU legislation and discuss drawbacks of existing analytical methods with respect to OO. Suggestions for replacement of specific steps within the present EU methods with more efficient analytical solutions to reduce time and/or solvent consumption will be proposed. Key findings and conclusions: This review critiques existing regulatory methods and standards, highlights weaknesses and proposes possible solutions to safeguard the consumer and protect the OO market.
Grasas y Aceites, 2016
This work tackles the study of the quality and authenticity of oils labeled and commercialized as... more 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 hyd...
Food Additives & Contaminants: Part A, 2016
Olive fruits contain an n-alkane series of saturated hydrocarbons mainly in the pulp. Lower amoun... more Olive fruits contain an n-alkane series of saturated hydrocarbons mainly in the pulp. Lower amounts of a complex mixture of paraffins, unresolved by gas chromatography (UCM), have been found in cuticle, stone (woody shell and seed), olive leaves, and talc used as an aid to olive oil extraction. The amounts of both kinds of hydrocarbons are related to the olive cultivar and are transferred to oils in a proportion depending on the oil obtaining process (centrifugation or solvent extraction). In olive oil obtained by centrifugation only n-alkanes were detected. However in olive oil extracted by second centrifugation, small amounts of UCM paraffins were detected together with the n-alkanes. Olive-pomace oils showed a
American Journal of Agricultural Science and Technology, 2015
This work extends previous research regarding the role of (esterified) steryl glucosides-(E)SG-in... more This work extends previous research regarding the role of (esterified) steryl glucosides-(E)SG-in olive oil. In line with previous research and to contribute to a comprehensive olive oil chemical characterization, we have determined the profile and content of these compounds in different mono-variety virgin olive oils using cholesterol β-D-glucoside (ChSG) as single internal standard. To do this, we have collected 22 types of olive cultivars, extracted the oils by the Abencor® method and applied a formerly developed SPE protocol. We have also determined the corresponding response factors with respect to the internal standard. Additionally, we have analyzed some of the purity and quality parameters included in the Regulations with the aim of understanding their relationship with those sterol derivatives. Results show the feasibility of using ChSG as internal standard, shortening the global time of analysis. They also confirm the suitability of the limits previously established for the presence of ESG in olive oil (0.2-14.0 mg. kg-1), but almost double those for SG (up to 4.77 mg. kg-1). Data also indicates the lack of a direct, stoichiometric relationship between some possible substrates (sterols, free fatty acids and related compounds) and the products-(E)SG-. Future lines of research are therefore outlined.
Grasas y Aceites, 2003
Método mejorado para la determinación de triglicéridos en aceites de oliva mediante cromatografía... more Método mejorado para la determinación de triglicéridos en aceites de oliva mediante cromatografía líquida de alta eficacia. El análisis de triacilgliceroles tiene gran importancia como herramienta en el control de calidad y en la determinación del origen de los aceites de oliva. Nuevas mejoras en el análisis de triacilgliceroles en aceite de oliva mediante cromatografía líquida de alta eficacia se han desarrollado para mejorar la separación entre las parejas críticas LLL/OLLn y OLL/OOLn usadas en la detección de aceites de semilla en aceite de oliva. Eluciones con acetona/acetonitrilo (55:45) usando gradiente de temperatura y elución con propionitrilo en condiciones isotérmicas han sido investigadas en comparación con el método oficial de la Unión Europea. La mejor resolución se consiguió usando propionitrilo como eluyente a 20 ºC. Aunque el perfil cromatográfico obtenido usando propionitrilo fue similar al obtenido usando acetona/acetonitrilo, se encontraron diferencias en los triacilgliceroles minoritarios que contribuyen a cada pico cromatográfico. La precisión del método fue buena.
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Papers by Wenceslao Moreda