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- Atividade antioxidante de Passiflora edulis Sims edulis ao longo da maturaçãoPublication . Souza, Nathália Bertoto Mercante de; Pereira, J.A.; Lopes-da-Silva, M.F.; Malheiro, RicardoO maracujá-roxo (Passiflora edulis Sims edulis) tem ganho destaque pelo elevado valor organolético do seu fruto e pelas propriedades biológicas que apresenta. No entanto, as cascas e as sementes são subprodutos industriais que poderão ser valorizados tendo em vista o seu potencial bioativo. A maturação é um fator preponderante na composição do fruto, não havendo informação sobre alterações nas diferentes partes do fruto. Neste sentido, no presente trabalho estudou-se o efeito da maturação do fruto ao nível da atividade antioxidante e composição fitoquímica das diferentes partes do maracujá-roxo (polpa, casca e sementes). Assim sendo, as diferentes partes do maracujá-roxo foram separadas em cinco graus de maturação de acordo com a coloração da casca (G1 – mais verde a G5 – mais maduro). Para cada grau de maturação e matriz estudada, procedeu-se à preparação de extratos metanólicos, onde foi avaliada a atividade antioxidante (atividade antiradicalar e poder redutor) e o teor em compostos fenólicos (fenóis totais, derivados do ácido hidroxicinâmico e flavonóis). Na polpa registaram-se maiores rendimentos de extração, no entanto, o maior potencial antioxidante foi observado nos extratos das cascas, seguido das sementes e polpa. A atividade antioxidante das cascas aumentou com o avanço da maturação, tendo-se verificado menor potencial antioxidante e teor em fitoquímicos na polpa. As sementes apresentaram valores mais elevados de fenóis totais, derivados do ácido hidroxicinâmico e flavonóis. Nas diferentes partes do maracujá-roxo verificou-se uma correlação entre a atividade antioxidante registada e o teor em fenóis totais. A maturação provoca alterações ao nível das diferentes partes do maracujá-roxo, sendo importante conhecê-las para estabelecer uma época de colheita que permita obter produtos com elevado potencial bioativo e teor em fitoquímicos, sendo também importante para se poder valorizar os seus subprodutos, principalmente as cascas.
- Aromatized olive oils: Influence of flavouring in quality, composition, stability, antioxidants, and antiradical potentialPublication . Sousa, Anabela; Casal, Susana; Malheiro, Ricardo; Lamas, Hugo; Bento, Albino; Pereira, J.A.In the present work different flavourings (garlic, hot chili peppers, laurel, oregano and pepper) commonly used in Mediterranean cuisine were added to olive oils from Cv. Cobrançosa. Flavouring influence in olive oils quality, fatty acids profile, tocopherols and tocotrienols composition, antiradical activity, total phenols content and oxidative stability were evaluated. Garlic addition induced an increase in free acidity values (from 0.6 to 0.8%), but the remaining quality indices weren't negatively affected. Fatty acids profile changed but values remained under the limits of extra-virgin olive oils. Olive oils were nutritionally enriched due to the increase in vitamin E, mainly in oils flavoured with hot chili pepper (198.6 mg/kg). Antioxidant properties were influenced as well. Total phenols content decreased in all flavoured olive oils (control with 345.7 mg CAE/kg; oregano 293.8 mg CAE/kg) but the capability to counteract oxidation was generally improved (control with 9.4 h and oregano with 10.4 h). The addition of flavouring influenced quality, composition and olive oils characteristics being possible to separate them according to the flavouring used by applying chemometrics.
- Influence of fruit traits on oviposition preference of the olive fly, Bactrocera oleae (Rossi) (Diptera: Tephritidae), on three Portuguese olive varieties (Cobrançosa, Madural and Verdeal Transmontana)Publication . Gonçalves, Fátima M.; Malheiro, Ricardo; Casal, Susana; Torres, Laura; Pereira, J.A.The olive fly, Bactrocera oleae (Rossi), is the major pest of olives in Mediterranean countries. Previous studies have stated that different olive tree varieties are not infested at the same time. Thus, in this work, the objective was to investigate several fruit physical and chemical parameters that could influence the B. oleae infestation progress in three olive varieties with different susceptibility degrees (Cobranc¸ osa, Madural and Verdeal Transmontana). Concerning physical parameters, the influence of maturity index, weight, volume and puncture resistance was studied, while in chemical parameters moisture, oil content and fatty acids composition were determined. Physical factors do not seem to be a determinant factor for selection of varieties. However, such factors could be important within the variety since the oviposition was correlated with some of them, being positively correlated with maturity index and negatively correlated with hardness in all varieties, with the stronger correlations observed in Cobranc¸ osa. For Madural and Cobranc¸ osa, a positive correlation was also established between oviposition and weight and volume. Concerning the chemical parameters, based on the principal component analysis, it was possible to separate the three varieties, which allows for concluding that they are chemically distinct. There are reasons to believe that some of these chemical parameters, namely the fatty acids composition, may influence the olive fly in the selection of the olive variety for oviposition.
- Olive volatiles from portuguese cultivars Cobrançosa, Madural and Verdeal Transmontana: role in oviposition preference of Bactrocera oleae (Rossi) (Diptera: Tephritidae)Publication . Malheiro, Ricardo; Casal, Susana; Cunha, Sara C.; Baptista, Paula; Pereira, J.A.The olive fly, Bactrocera oleae (Rossi), a serious threat to the olive crop worldwide, displays ovipositon preference for some olive cultivars but the causes are still unclear. In the present work, three Portuguese olive cultivars with different susceptibilities to olive fly (Cobrançosa, Madural, and Verdeal Transmontana) were studied, aiming to determine if the olive volatiles are implicated in this interaction. Olive volatiles were assessed by SPME-GC-MS in the three cultivars during maturation process to observe possible correlations with olive fly infestation levels. Overall, 34 volatiles were identified in the olives, from 7 chemical classes (alcohols, aldehydes, aromatic hydrocarbons, esters, ketones, sesquiterpenes, and terpenes). Generally, total volatile amounts decrease during maturation but toluene, the main compound, increased in all cultivars, particularly in those with higher susceptibility to olive fly. Sesquiterpenes also raised, mainly α-copaene. Toluene and α-copaene, recognized oviposition promoters to olive fly, were correlated with the infestation level of cvs. Madural and Verdeal Trasnmontana (intermediate and highly susceptible cultivars respectively), while no correlations were established with cv. Cobrançosa (less susceptible). No volatiles with inverse correlation were observed. Volatile composition of olives may be a decisive factor in the olive fly choice to oviposit and this could be the basis for the development of new control strategies for this pest.
- How Agronomic Factors Affects Olive Oil Composition And QualityPublication . Malheiro, Ricardo; Casal, Susana; Baptista, Paula; Pereira, J.A.Olive oil is one of the most popular vegetable oils worldwide but several factors might affect its quality and composition, from the tree to the spoon. Olive oil quality and composition is mainly influenced by olive fruit characteristics, and therefore all aspects that influence their development have a crucial effect on olive products. Those factors include the selection of olive cultivar, its cultivation, degree of crop intensification and production systems, agricultural practices, including irrigation and fertilization, olive pests and diseases management, all these factors clearly defining the composition of olive fruits and the inherent quality and properties of olive products. In the last decades, huge modifications in olive tree cultivation have been observed, related essentially with two great factors: development of olive cultivations in new producing areas and crop intensification in traditional producing areas. Generally, most agronomic factors, including crop density, farming system, irrigation and fertilization, have no substantial effects on fresh olive oil quality parameters and classification. Nevertheless, a considerable incidence of olive pests and diseases can easily take fresh olive oils to the lampante category. In opposition, all agronomic factors seem to influence olive oil composition. Antioxidants are the main affected components, with a crucial effect on olive oil sensorial attributes, bioactive and nutritional properties, as well as its oxidative stability. In present chapter the influence of diverse agronomic factors on olive fruits and olive oils production, composition and quality, is reviewed and discussed, giving special importance to olive farming-systems, fertilization and irrigation, as well as the incidence of olive pests and diseases.
- Physicochemical characterization of a traditional portuguese bread (pão transmontano) towards its future certification – preliminary resultsPublication . Magalhães, Agostinho; Pereira, Ermelinda; Pawlak, Chalissa; Malheiro, Ricardo; Ferreira, Elisabete; Pereira, J.A.; Ramalhosa, ElsaThe Trás-os-Montes region, Northeast of Portugal, is a region rich in traditions and typical products with different flavors, being the bread one of the most appreciated products. Its importance derives not only from the direct consumption, but also of its inclusion as an ingredient in different products of which it stand out the sausages so famous in the region. In this regard the preservation of knowledge, genuineness and authenticity associated with the production of bread in Trás-os-Montes region according to traditional processes, is one of the most important and current aspects so as not to miss this accumulated knowledge over generations. In the present work two breads from Vale de Nogueira and Bragança were physicochemical characterized in order to collect data for Pão Transmontano future certification. Results regarding dimensions, colour, water activity, pH, moisture, ash, salt, fat, protein and total dietary fibre contents are presented and discussed, being both breads compared with the "common" wheat bread. The mean composition of this bread is described on the Food Composition Table that is a national reference paper for the composition of food products and is regularly updated by “Instituto Ricardo Jorge”, a well-known Portuguese institution. The breads of Vale de Nogueira and Bragança showed lower fat and protein contents than the "common" wheat bread. In terms of the colour coordinates for the crust and crumbs, both breads presented similar values in relation to L*, a*, b*, chroma or saturation (C*) and hue angle (h*), indicating that the major differences are found in their nutritional composition instead format and colour.
- Olive oil stability under deep-frying conditionsPublication . Casal, Susana; Malheiro, Ricardo; Sendas, A.; Oliveira, Beatriz; Pereira, J.A.The suitability of different commercial olive oil categories for domestic frying was investigated. Oil samples were taken every 3 h of frying and evaluated for free acidity, peroxide and p-anisidine values, specific extinction coefficients, oxidative stability, fatty acids, vitamin E, b-carotene and total phenols, until the total polar compounds achieved the maximum legal value (25%). All olive oils were fried during more time than the commercial vegetable oil blend taken for comparison (from 24 to 27 h, against 15 h). The extra-virgin Protected Designation of Origin (PDO) olive oil was characterized by reduced levels of oxidation and hydrolysis, and superior amounts of minor antioxidant compounds. The ‘‘olive oil” commercial category behaves similarly, but ‘‘Cobrançosa” olive oils performance was slightly worse, and clearly different between years, highlighting the importance of blending different cultivars. The vegetable oil, despite containing significantly higher amounts of vitamin E, was highly susceptible to oxidation under frying conditions when compared to all olive oils. The results also show that the chemical composition of olive oils, particularly the amount of natural antioxidants, are important parameters in their predictive behavior along the frying process, but mostly that olive oil is clearly resistant to frying conditions, independently to the commercial category chosen.
- Effect of cultivar on sensory characteristics, chemical composition, and nutritional value of stoned green table olivesPublication . Malheiro, Ricardo; Casal, Susana; Sousa, Anabela; Pinho, P. Guedes de; Peres, António M.; Dias, L.G.; Bento, Albino; Pereira, J.A.The effect of olive cultivar on sensory characteristics, chemical composition, and nutritional value of traditional stoned green table olives “alcaparras” was studied. The most representative cultivars from Trás-os-Montes region, Portugal (Cv. Cobrançosa, Madural, Negrinha de Freixo, Santulhana, and Verdeal Transmontana) were studied. The results showed that, regardless the cultivar, water was the main constituent with values greater than 70%, followed by fat that varied between 12.5% and 20.1%. Carbohydrates amount was greater in Cv. Madural (9.2%) and those produced from Cv. Cobrançosa had higher level of nitrogenous compounds, with 1.4%. Ashes contents of table olives varied from 1.6% to 1.9%, without significant differences among cultivars. Moreover, 100 g of “alcaparras” provided an energetic value between 154 and 212 kcal for Cv. Madural and Verdeal Transmontana, respectively. Oleic acid was the main fatty acid detected (higher than 66.9%), followed by palmitic acid (10.8–13.3%) and linoleic acid (2.7–10.3%). A linear discriminant model was established based on the “alcaparras” table olives fatty acids profile. Three fatty acids (C16:0, C18:0, and C18:3) and total saturated fatty acids, monounsaturated fatty acids, and polyunsaturated fatty acids contents allowed distinguishing between the five olive cultivars studied, with overall sensitivity and specificity of 100%. The total content of vitamin E of the table olives varied from 3.5 and 6.0 mg/kg (for Cv. Santulhana and Negrinha de Freixo, respectively), being α-tocopherol the most abundant. The consumer’s panel showed higher preference for the table olives of Cv. Verdeal Transmontana and Negrinha de Freixo, while Cv. Madural was negatively characterized in all the descriptors evaluated. Keywords Olea europaea L. . Stoned table olives.
- Antimicrobial activity of endophytic fungi from olive tree leavesPublication . Malhadas, Cynthia; Malheiro, Ricardo; Pereira, J.A.; Pinho, P. Guedes de; Baptista, PaulaIn this study, the antimicrobial potential of three fungal endophytes from leaves of Olea europaea L. was evaluated and the host plant extract effect in the antimicrobial activity was examined. The volatile compounds produced by endophytes were identified by GC/MS and further correlated with the antimicrobial activity. In potato dextrose agar, both Penicillium commune and Penicillium canescens were the most effective inhibiting Gram-positive and -negative bacteria (up to 2.7-fold compared to 30 µg/mL chloramphenicol), whereas Alternaria alternata was most effective inhibiting yeasts (up to 8.0-fold compared to 25 μg/mL fluconazole). The presence of aqueous leaf extract in culture medium showed to induce or repress the antimicrobial activity, depending on the endophytic species. In the next step, various organic extracts from both A. alternata mycelium and cultured broth we re prepared; being ethyl acetate extracts displayed the widest spectrum of anti-microorganisms at a minimum inhibitory concentration ≤0.095 mg/mL. The volatile composition of the fungi that displayed the highest (A. alternata) and the lowest (P. canescens) antimicrobial activity against yeasts revealed the presence of six volatiles, being the most abundant components (3-methyl-1-butanol and phenylethyl alcohol) ascribed with antimicrobial potentialities. Overall the results highlighted for the first time the antimicrobial potential of endophytic fungi from O. europaea and the possibility to be exploited for their antimicrobial agents. Graphical Abstract: [Figure not available: see fulltext.]
- Antioxidant activity and phenolic composition of Cv. Cobrançosa olives affected through the maturation processPublication . Sousa, Anabela; Malheiro, Ricardo; Casal, Susana; Bento, Albino; Pereira, J.A.Maturation stage is a critical feature to obtain high quality olive products, with maximized bioactivity. In this study, phenolic composition and antioxidant activity of Cv. Cobrançosa through the maturation process were evaluated.The phenolic profile was assessed by HPLC/ DAD, and antioxidant activity was studied through its reducing power and free-radical scavenging activity. Total phenols varied from 34 to 1 g/kg, respectively, in the first and last sampling dates. Oleuropein, the main phenolic in the first stages of maturation, decreased drastically during ripening. At intermediate and high maturation stages hydroxytyrosol was the predominant phenol. Globally, the reducing capacity of Cv. Cobrançosa olive fruits decreased during the maturation process but its radical scavenging activity was only slightly altered. A principal components analysis corroborated the characteristic phenolic profile and changes experienced by the olive fruit during the maturation process. These results are important to maximize Cv. Cobrançosa olive products’ quality and biological properties.