Author
L.F.Vilas Boas
Bio: L.F.Vilas Boas is an academic researcher from Instituto Superior Técnico. The author has contributed to research in topics: Circular dichroism & Potentiometric titration. The author has an hindex of 13, co-authored 18 publications receiving 720 citations.
Papers
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TL;DR: In this paper, a reverse phase HPLC with diode array detection and mass spectrometry (MS) was used to identify common phenolic compounds, such as verbascoside, rutin, luteolin-7-glucoside and hydroxytyrosol.
Abstract: Extracts of leaves, fruits and seeds of olive tree cultivars of Tras-os-Montes e Alto Douro (Portugal) were analysed by reverse phase HPLC with diode array detection and mass spectrometry (MS). This methodology allowed the identification of some common phenolic compounds, namely, verbascoside, rutin, luteolin-7-glucoside, oleuropein and hydroxytyrosol. Moreover the hyphenation of HPLC with MS enabled the identification of nuzhenide in olive seeds. An oleuropein glucoside was also detected in olive tree leaves. The total phenolic content was determined with the Folin Denis reagent and the total antioxidant activity with the ABTS method. There is a correlation between total antioxidant activity and total phenolic content with the exception of the seed extracts analysed. The apparent high antioxidant activity of seed extracts may be due to nuzhenide, a secoiridoid that is the major phenolic component of olive seeds. These results suggest a possible application of olive seeds as sources of natural antioxidants.
264 citations
TL;DR: A liquid chromatography method associated with mass spectrometry and diode array, fluorescence and electrochemical detectors was used in order to study phenolic composition of Muscatel sweet wines from Set´ ubal region in Portugal.
131 citations
TL;DR: In this article, the equilibria in aqueous solution in the system L -alanine+VO 2+ have been studied by a combination of pH-potentiometric and spectroscopic methods (EPR, visible absorption and circular dichroism) in the pH range 1.5-13.
55 citations
TL;DR: In this paper, the free fatty acids, triglycerides and volatile compounds in Serra da Estrela cheese were analysed and changes throughout ripening were examined, showing that free fatty acid showed a general increase until the 3rd week of ripening.
46 citations
TL;DR: In this article, the equilibria in the system l -aspartic acid +VO 2+ in aqueous solution for 1.5 ⪕ pH ⫕ 11 have been studied by a combination of pH-potentiometric and spectroscopic methods [electron paramagnetic resonance (EPR), visible absorption and circular dichroism (CD)].
38 citations
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TL;DR: Aqueous V(III) Chemistry 877 6.2.1.
Abstract: 6.1.2. Aqueous V(III) Chemistry 877 6.1.3. Oxidation State of Vanadium in Tunicates 878 6.1.4. Uptake of Vanadate into Tunicates 879 6.1.5. Vanadium Binding Proteins: Vanabins 879 6.1.6. Model Complexes and Their Chemistry 880 6.1.7. Catechol-Based Model Chemistry 880 6.1.8. Vanadium Sulfate Complexes 881 6.2. Fan Worm Pseudopotamilla occelata 883 7. Vanadium Nitrogenase 883 7.1. Nitrogenases 883 7.2. Biochemistry of Nitrogenase 884 7.3. Clusters in Nitrogenase and Model Systems: Structure and Reactivity 885
1,184 citations
TL;DR: In this article, the main forms of caprine and ovine caseino-macropeptides (CMP), which are the soluble C-terminal derivatives from the action of chymosin on β-casein during the milk clotting process of cheesemaking, have been identified and are a good source of antithrombotic peptides.
1,120 citations
TL;DR: A survey on phenolic compounds of virgin olive oils bearing in mind their chemical-analytical, healthy and sensory aspects is realized, starting from the basic studies, the results of researches developed in the last ten years will be focused.
Abstract: Among vegetable oils, virgin olive oil (VOO) has nutritional and sensory characteristics that to make it unique and a basic component of the Mediterranean diet. The importance of VOO is mainly attributed both to its high content of oleic acid a balanced contribution quantity of polyunsaturated fatty acids and its richness in phenolic compounds, which act as natural antioxidants and may contribute to the prevention of several human diseases. The polar phenolic compounds of VOO belong to different classes: phenolic acids, phenyl ethyl alcohols, hydroxy-isochromans, flavonoids, lignans and secoiridoids. This latter family of compounds is characteristic of Oleaceae plants and secoiridoids are the main compounds of the phenolic fraction. Many agronomical and technological factors can affect the presence of phenols in VOO. Its shelf life is higher than other vegetable oils, mainly due to the presence of phenolic molecules having a catechol group, such as hydroxytyrosol and its secoiridoid derivatives. Several assays have been used to establish the antioxidant activity of these isolated phenolic compounds. Typical sensory gustative properties of VOO, such as bitterness and pungency, have been attributed to secoiridoid molecules. Considering the importance of the phenolic fraction of VOO, high performance analytical methods have been developed to characterize its complex phenolic pattern. The aim of this review is to realize a survey on phenolic compounds of virgin olive oils bearing in mind their chemical-analytical, healthy and sensory aspects. In particular, starting from the basic studies, the results of researches developed in the last ten years will be focused.
728 citations
TL;DR: In this article, the progress of lipolysis and its effect on flavour development during cheese ripening is reviewed and the current methods for quantification of free fatty acids in cheese are compared and compared.
634 citations
TL;DR: Hyphenated techniques involving a highly efficient separation and a highly sensitive detection have resulted in the determination of new arsenic species, contributing to a better understanding of arsenic metabolism and biogeochemical cycling.
359 citations