Authentication of vegetable oils.

Authenticity of vegetable oils continues to be a challenge and the target of many studies. Consumers expectancy on healthier products that conform to the labelled information, and the vast amount of legislation a bout the correct characterisation and classification of vegetable oils have boosted a number of scientific works on this subject. Analytical t echniques to face this challenge are, at least, as manifold as ar e the ways of adulteration, ranging from classical determination of chemical parameters to highly sophisticated instrumental and molecular biology techniques. Rather than being an exhaustive revision of published works, the aim of the present chapter is to summarise: i) the analytical methods used in the determination of the main oil components such as fatty acids, triacylglycerols, phytosterols, tocopherols and tocotrienols, phenolic compounds, pigments and volatile compounds, emphasising their importance in authenticity evaluation; ii) the alternative tech niques based on spectroscopic

Quantification of tocopherols and tocotrienols in Portuguese olive oils using HPLC with three different detection systems

Three different HPLC detection systems were compared for the determination of tocopherols and tocotrienols in olive oil: fluorescence and diode array connected in series, ultraviolet, and evaporative light scattering. The best results were obtained with the fluorescence detector, which was successfully applied in the quantification of tocopherols and tocotrienols in 18 samples of Portuguese olive oils. To support the validity of the method, the parameters evaluated were linearity, detection limits, repeatability, and recovery. All of the studied samples showed similar qualitative profiles with six identified compounds: R-T, -T, γ-T, δ-T, R-T3, and γ-T3. R-Tocopherol (R-T) was the main vitamin E isomer in all samples ranging from 93 to 260 mg/kg. The total tocopherols and tocotrienols ranged from 100 to 270 mg/kg. Geographic origin did not seem to influence the tocopherol and tocotrienol composition of the olive oils under evaluation

Classification PDO olive oils on the basis of their sterol composition by multivariate analysis

The sterol compositions (GLC/FID/capillary column) of monovarietal olive oils (51 samples) from the most important cultivars of northeastern Portugal (Cvs. Cobranc¸osa, Madural and Verdeal Transmontana) and 27 commercial samples of olive oils with protected denomination of origin (PDO) from the same region and cultivars were evaluated. Δ-sitosterol, Δ5-avenasterol and campesterol were the most representative sterols. Cholesterol, stigmasterol, clerosterol and Δ7-stigmastenol were also found in all samples. All studied samples respected EC Regulation N. 2568, and in all cases total sterols were remarkably higher than the minimum limit set by legislation, ranging from 2003 to 2682 mg/kg. Results were analysed with the help of several statistical techniques, including reduction of dimensionality by principal component analysis with cross-validation of the number of components, followed by the use of canonical variate predictive biplots for model development and canonical variate interpolative biplots for approximate classification of monovarietal and PDO olive oils. These biplots proved to be a very interesting solution in the present case study, overcoming the problems of interpretation and classification that arise whenever different multivariate analyses are coupled together

Caracterização química de azeites elementares da região de Trás-os-Montes.

Trás-os-Montes é uma das principais regiões produtoras de azeite a nível nacional, onde é produzido azeite com a Denominação de Origem Protegida “Azeite de Trás-os-Montes”. De uma forma geral, estes azeites resultam de uma mistura de diferentes cultivares, maioritariamente Cobrançosa, Madural e Verdeal Transmontana, sendo permitida a presença de outras, ainda que em menor proporção. Com o presente trabalho pretendeu-se contribuir para a caracterização química de azeites elementares produzidos na região de Trás-os-Montes. Assim, foram analisadas 80 amostras de azeite das cultivares Cobrançosa (20), Verdeal Transmontana (11), Madural (11), Santulhana (11), Negrinha de Freixo (11), Cordovil (10), Borrenta (2), Bical (1), Cordovesa (1), Lentisca (1) e Madural Negra (1), num total de 11 cultivares, tendo sido caracterizados no que respeita à acidez, índice de peróxidos, absorvência no ultravioleta, teor em clorofilas e carotenóides e composição em ácidos gordos

Angolan cymbopogon citratus used for therapeutic benefits: nutritional composition and influence of solvents in phytochemicals content and antioxidant activity of leaf extracts

Folk medicine is a relevant and effective part of indigenous healthcare systems which are, in practice, totally dependent on traditional healers. An outstanding coincidence between indigenous medicinal plant uses and scientifically proved pharmacological properties of several phytochemicals has been observed along the years. This work focused on the leaves of a medicinal plant traditionally used for therapeutic benefits (Angolan Cymbopogon citratus), in order to evaluate their nutritional value. The bioactive phytochemical composition and antioxidant activity of leaf extracts prepared with different solvents (water, methanol and ethanol) were also evaluated. The plant leaves contained ~60% of carbohydrates, protein (~20%), fat (~5%), ash (~4%) and moisture (~9%). The phytochemicals screening revealed the presence of tannins, flavonoids, and terpenoids in all extracts. Methanolic extracts also contained alkaloids and steroids. Several methods were used to evaluate total antioxidant capacity of the different extracts (DPPH; NO; and H2O2 scavenging assays, reducing power, and FRAP). Ethanolic extracts presented a significantly higher antioxidant activity (p < 0.05) except for FRAP, in which the best results were achieved by the aqueous extracts. Methanolic extracts showed the lowest radical scavenging activities for both DPPH; and NO; radicals

Advances in isoflavone profile characterisation using matrix solid-phase dispersion coupled to HPLC/DAD in medicago species

Analytical methods used in phytochemistry analysis are limited by the sample preparation step, which should ideally be fast, accurate, ecofriendly and achievable using low quantities of the sample. Matrix solid-phase dispersion (MSPD) may be a good alternative for combining extraction and purification procedures, thereby reducing the indicated limitations. Objective-Applying an MSPD extraction procedure coupled to high-performance liquid chromatography diode-array detection (HPLC/DAD) as an alternative methodology to evaluate isoflavone profiles. Methods-Isoflavone profiles were determined for the leaves of nine species of Medicago in the late flower phenological stage (one or more nodes with 50% open flowers, no seed pods). Extraction was performed following MSPD, and isoflavone profiles were characterised using HPLC/DAD. The quantified amounts were compared with previous results in different species commonly recognised as good sources of isoflavones. Results-Formononetin was the major isoflavone in most species, except M. polymorpha and M. truncatula. The isoflavone amounts were significantly different among the assayed species, with M. orbicularis and M. arabica as the major isoflavone sources, while M. rigidula presented the lowest contents. Furthermore, the detected differences allow electing the best species as a primary source of a specific isoflavone. Conclusion-The MSPD allowed good extraction efficiency, reproducibility and recovery. Some of the species showed relevant isoflavone contents, even when compared with acknowledged plant sources such as soy or red clover. To the best of our knowledge the results presented are reported for the first time in these species.T. Visnevschi-Necrasov and João C.M. Barreira are grateful to ‘FCT - Fundação para a Ciência e a Tecnologia’ for their grants (BD/ 31734/2006 and SFRH/BPD/72802/2010, respectively). S.C. Cunha is grateful to ‘POPH-QREN - Tipologia 4.2, Fundo Social Europeu e Fundo Nacional MCTES’.info:eu-repo/semantics/publishedVersio

Medicago spp. as potential sources of bioactive isoflavones: Characterization according to phylogenetic and phenologic factors

A high variety of plant species are often proposed as potential natural sources of specific bioactive components, with emphasis in phenolic compounds. However, the ability to produce a determined phytochemical might be variable, even among species with close phylogeny. Furthermore, the metabolic dynamics vary greatly according to phenologic factors. Herein, it was verified whether isoflavone production in Medicago spp. is more associated with phylogenetic or phenologic determinants, to define the optimal productive conditions. Isoflavone profiles were characterized in field-grown Medicago species in three phenologic stages. Isoflavones were extracted by matrix solid-phase dispersion method and analyzed using high-performance liquid chromatography coupled with a diode-array detector. The obtained data were evaluated by a generalized linear model (GLM) and linear discriminant analysis (LDA). Formononetin, genistein and irilone were the most abundant isoflavones, reaching values higher than those present in acknowledged plant sources like soy or red clover. Outputs from GLM and LDA indicate that the phylogenetic factors are the most defining criteria. This study promotes Medicago spp. as potential isoflavone sources, particularly because the effects of these compounds are highly dependent on their type and concentration, with potential application as foodstuff, feedstuff, or in the nutraceutical and pharmaceutica l industry.Visnevschi-Necrasov and João C.M. Barreira are grateful to ‘‘FCT – Fundação para a Ciência e a Tecnologia’’ for their Grants (SFRH/BD/31734/2006 and SFRH/BPD/72802/2010, respectively). S.C. Cunha is grateful to ‘‘POPH-QREN – Tipologia 4.2, Fundo Social Europeu e Fundo Nacional MCTES’’.info:eu-repo/semantics/publishedVersio

Teores de vitamina E em diferentes variedades de castanea sativa

Vitamina E é a designação comum de uma familia de compostos relacionados, nomeadamente as tocoferóis e as tocotrienóis, caracterizada por conter uma cadeia lateral isoprénica Iigada ao cromanol [1]. A caracterização qualitativa e quantitativa dos diferentes vitâmeros, apesar de estruturalmente similares, é fundamentada pelas diferenças nas respectivas actividades biológicas

Phylogenetic insights on the isoflavone profile variations in Fabaceae spp.: Assessment through PCA and LDA

Legumes (Fabaceae) are important crops, known as sources of food, feed for livestock and raw materials for industry. Their ability to capture atmospheric nitrogen during symbiotic processes with soil bacteria reduces the need for expensive chemical fertilizers, improving soil and water quality. Several Fabaceae species are acknowledged for the high levels of secondary metabolites. Isoflavones are among the most well-known examples of these compounds, being recognized for their several types of biological activity. Herein, isoflavone profiles were characterized in nine species of four Fabaceae genera (Biserrula, Lotus, Ornithopus and Scorpiurus). Plants were harvested in the late flower physiological stage to prevent biased results due to naturally occurring variations along the vegetative cycle. Isoflavones were extracted using matrix solid-phase dispersion and analyzed by high performance liquid chromatography/diode-array detection. The detected profiles revealed significant differences, inclusively among species belonging to the same genus, indicating that other factors besides the genotypic features contribute to the expression of these phenolic compounds. The classification of the results by principal component analysis placed species belonging to the same genus in different clustering groups, proving this latter assumption. However, the detected profiles proved to be characteristic of the assayed, as it was proved by the applied linear discriminant analysis.info:eu-repo/semantics/publishedVersio