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- Evaluation of the chemical interactions in co-culture elements of Castanea sativa Miller mycorrhizationPublication . Carvalho, Filipa Arminda; Ferreira, Isabel C.F.R.; Barreira, João C.M.; Barros, Lillian; Martins, AnabelaIn the early steps of mycorrhizal associations an oxidative burst might occur through the rapid production of high amounts of reactive oxygen species in response to external stimuli, increasing the production of antioxidants in plant and/or mycelia. Herein, the effect of mycorrhizal association among Pisolithus arhizus or Paxillus involutus and Castanea sativa Miller (stems and roots) was studied for different co-culture periods, defined for a better comprehension of the chemical interactions in the early stages of mycorrhization (6, 24 and 72 h). Knowledge on the specificities of plant-host interaction provided information about the most suitable fungus to be included in the development of new management strategies, and the fungal species that induced the strongest response with increasing antioxidant activity (free radical scavenging activity, reducing power and lipid peroxidation inhibition) and production of antioxidant compounds (phenolics and tocopherols) and sugars. P. involutus seemed to be the most adequate fungus to mycorrhize with C. sativa. Considering bioactive compounds production, P. arhizus was more efficient since allowed an increase in the contents of sugars and tocopherols in all co-culture elements.
- Chemical composition of Boletus pinophilus and Clitocybe subconnexa: preservation with gamma irradiationPublication . Fernandes, Ângela; Antonio, Amilcar L.; Barreira, João C.M.; Martins, Anabela; Oliveira, Beatriz; Ferreira, Isabel C.F.R.The short shelf life of mushrooms is a barrier for their distribution and, therefore, there has been extensive research to find technologies that ensure the preservation of mushrooms, maintaining their organoleptic and nutritional properties (1]. Irradiation has proved its technological feasibility to be safely used in the reduction of food losses, being recognized by international organizations as a valid conservation alternative in extending shelflife of many foods. The aim of the present work was to validate the use of 2 kGy dose of gamma radiation to maintain chemical composition of wild mushrooms. Boletus pinophilus Pihit & Dermek and Clitocybe subconnexa Murrill wild samples were obtained in Tnis-os-Montes; subsequently, the samples were divided in two groups: control (non-irradiated, 0 kGy) and irradiated (2 kGy). The irradiation of the samples was performed in a 6°Co experimental chamber. Moisture, protein, fat, carbohydrates and ash were determined following the standard procedures [2]. Free sugars and tocopherols were determined by high performance liquid chromatography coupled to a refraction index detector (HPLC-RI) and a fluorescence detector, respectively; fatty acids were determined by gas-liquid chromatography with flame ionization detection (GC-FID) [3]. The protein and ash content was preserved in both groups, although the sugars and tocopherols decreased in the irradiated samples. Sugars and fatty acids showed significant changes after irradiation treatment, particularly in B. pinophillus, nevertheless, the magnitude of the obtained differences did not seem to be sufficient to affect the chemical profiles of the assayed mushrooms. Overall, the detected chemical changes might be considered as allowable, in view of the high advantages offered by gamma irradiation at decontamination and/or disinfestation level.
- Insights on the formulation of herbal beverages with medicinal claims according with their antioxidant propertiesPublication . Barreira, João C.M.; Morais, Ana L.; Ferreira, Isabel C.F.R.; Oliveira, BeatrizSeveral herbal beverages claim medicinal benefits due to their antioxidant properties. However, operational factors such as the extracted herbal component, preparation method or concentration levels, might influence their biological activity. To assess this effect, the antioxidant activity of beverages prepared with Camellia sinensis, Aspalathus linearis or Cochlospermum angolensis, used solely or mixed with different fruit, plant or algae extracts, was studied using different formulations (bags, leaves, roots, granulates, powders, liquids) and different preparation methods (infusion, solubilisation or promptly used). The DF50 (dilution factor responsible for 50% of antioxidant activity) values were calculated to compare their antioxidant activity. A linear discriminant analysis was used to categorize the assayed samples according to their antioxidant activity and bioactive molecules profiles. The results indicated that antioxidant activity and antioxidant compounds are significantly affected by formulation and preparation method, but overall the labelled antioxidant benefits were validated. Green tea showed the highest activity, but with different behaviour within each used formulation. The high DF50 values calculated for some products might be used to adjust the dietary dose or formulation, preventing also putative pro-oxidant effects. Hence, the obtained results might be useful to define the formulation of these highly consumed herbal beverages, enhancing their health effects.
- Antioxidant activity of portuguese honey samples: different contribution of the entire honey and phenolic extractPublication . Ferreira, Isabel C.F.R.; Aires, Edmur; Barreira, João C.M.; Estevinho, Leticia M.The antioxidant activity of Portuguese honeys was evaluated considering the different contribution of entire samples and phenolic extracts. Several chemical and biochemical assays were used to screen the antioxidant properties of entire honeys with different colour intensity and phenolic extracts: reducing power, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging capacity, and inhibition of lipid peroxidation using the b-carotene linoleate model system and the thiobarbituric acid reactive substances (TBARS) assay. The amounts of phenols, flavonoids, ascorbic acid, b-carotene, lycopene and sugars present in the samples were also determined. The highest antioxidant contents and the lowest EC50 values for antioxidant activity were obtained in the dark honey. An analysis of variance was carried out to evaluate the influence of the colour intensity and extraction method in the antioxidant properties and phenolic contents. A discriminant analysis was also performed, giving satisfactory results once the six samples were clustered in six individual groups obtained through the definition of two discriminant analysis dimensions.
- Bioactivity, proximate, mineral and volatile profiles along the flowering stages of Opuntia microdasys (Lehm.): defining potential applicationsPublication . Chahdoura, Hassiba; Barreira, João C.M.; Fernández-Ruiz, Virginia; Morales, Patricia; Calhelha, Ricardo C.; Flamini, Guido; Soković, Marina; Ferreira, Isabel C.F.R.; Achour, LotfiOpuntia spp. flowers have been traditionally used for medical purposes, mostly because of their diversity in bioactive molecules with health promoting properties. The proximate, mineral and volatile compound profiles, together with the cytotoxic and antimicrobial properties were characterized in O. microdasys flowers at different maturity stages, revealing several statistically significant differences. O. microdasys stood out mainly for its high contents of dietary fiber, potassium and camphor, and its high activities against HCT15 cells, Staphylococcus aureus, Aspergillus versicolor and Penicillium funiculosum. The vegetative stage showed the highest cytotoxic and antifungal activities, whilst the full flowering stage was particularly active against bacterial species. The complete dataset has been classified by principal component analysis, achieving clearly identifiable groups for each flowering stage, elucidating also the most distinctive features, and comprehensively profiling each of the assayed stages. The results might be useful to define the best flowering stage considering practical application purposes.
- Effects of gamma irradiation on sugars, fatty acids and tocopherols of chestnuts (Castanea sativa Miller)Publication . Barros, Lillian; Antonio, Amilcar L.; Barreira, João C.M.; Fernandes, Ângela; Bento, Albino; Botelho, M. Luísa; Ferreira, Isabel C.F.R.As seasonal products chestnuts have to be postharvest treated to increase their shelf-life. The most common preservation method for chestnuts is the use of chemical fumigation with methyl bromide, a toxic agent that is under strictly use under Montreal Protocol due to its adverse effects on human health and environment. Food irradiation is a possible feasible alternative to substitute the traditional quarantine chemical fumigation treatment. The main studies in chestnuts irradiation were done in an Asian variety, which is bigger and sweeter than the European types. However, on Portuguese varieties nothing has been reported. Herein, the influence of irradiation and storage time in sugars, fatty acids and tocopherols profiles/quantities in chestnuts obtained in Trás-os-Montes, Northeast Portugal, was evaluated for the fist time.
- Triacylglycerols profile and principal component analysis as a chemometric tool to identify wild edible mushroom generaPublication . Barreira, João C.M.; Oliveira, Beatriz; Ferreira, Isabel C.F.R.The Northeast of Portugal is among the European regions with high divers ity of wild mushrooms, some with recognized gastronomic value. Due to the high resemblance among mushroom species belonging to the same genus, finding a distinctive chemometric marker to identify mushroom species is a mandatory task. The lipidic fraction of a natural product has a characteristic pattern of triaeylglyccrol (TAG), comprising specific information due to the genetic control of the stereospecific distribution of fatty acids (FA) on the glycerol molecule, which is typical for each species. Principal component analysis (PCA) was previously applied to classify mushroom samples according to their fatty acids profile.121 However, despite TAG profile was used before to assess the authenticity of oils,l31 it was not used as taxonomical marker. Accordingly, TAG profile was evaluated in 30 wild mushroom species and the results were classified by PCA to identify their discriminant ability. TAG profiles obtained by high performance liquid chromatography coupled to an evaporative light scattering detector showed significant differences among species. The PCA biplot (1) showed that TAG profiles recorded for different mushroom genera may be used as an effective differentiating tool, especially when lowering the taxonomical rank, indicating that TAG profile is most related with the lowest ranks. Ln conclusion, this chemometric approach might be used as a practical tool to identify mushroom species.
- Edible flowers of Viola tricolor L. as a new functional food: Antioxidant activity, individual phenolics and effects of gamma and electron-beam irradiationPublication . Koike, Amanda; Barreira, João C.M.; Barros, Lillian; Santos-Buelga, Celestino; Villavicencio, Anna L.C.H.; Ferreira, Isabel C.F.R.Edible flowers are used in food preparations, being also recognized for their beneficial effects on human health. Nevertheless, these species are highly perishable, and irradiation treatment might be applied to ensure food quality and increase their shelf life. Viola tricolor L. is a typical edible flower, with multiple applications and biological properties, mainly provided by the flavonoid content. In the present work, the phenolic compounds were analyzed by HPLC-DAD-ESI/MS, and the antioxidant activity was evaluated using biochemical assays. Linear discriminant analyses (LDA) were performed in order to compare the results obtained with flowers submitted to different irradiation doses and technologies (cobalt-60 and electron-beam). In general, irradiated samples (mostly with 1 kGy) showed the highest phenolic content and antioxidant activity. Furthermore, the significant differences observed in the LDA allow determination of which dose and/or technology is suitable to obtain flowers with higher antioxidant potential.
- Different Citrus rootstocks present high dissimilarities in their antioxidant activity and vitamins content according to the ripening stagePublication . Cardeñosa, Vanessa; Barros, Lillian; Barreira, João C.M.; Arenas-Arenas, Francisco José; Moreno-Rojas, José M.; Ferreira, Isabel C.F.R.“Lane Late” sweet orange grafted on six different citrus rootstocks and grown in the Guadalquivir valley (Seville, Spain) were picked at different ripening stages in two consecutive seasons to characterize their antioxidant activity (free radicals scavenging activity, reducing power and lipid peroxidation inhibition) and quantify their main antioxidant compounds (vitamin E and vitamin C). Linear discriminant analysis and 2-way ANOVA were applied to compare the effects induced by citrus rootstock and ripening stage. The results showed that differences in antioxidant activity and related compounds are mainly dependent on the citrus rootstock, despite ripening stage had also some particular effects. Changes observed in 2012 showed less marked differences among the citrus rootstock. Nevertheless, Cleopatra rootstock showed the highest antioxidant activity in both years, indicating that an increase in its cultivation might be a good solution to sweet orange farmers. Concerning the ripening stage, samples collected in January presented higher vitamin contents, while those collected in April showed higher antioxidant activity. This result allows deciding the harvesting period according to the desired effect.
- Irradiação gama como uma alternativa segura para preservar as características químicas e bioativas de plantas utilizadas para fins medicinaisPublication . Pereira, Eliana; Antonio, Amilcar L.; Barreira, João C.M.; Barros, Lillian; Bento, Albino; Ferreira, Isabel C.F.R.As plantas usadas pela indústria requerem tecnologias de conservação e descontaminação eficazes a fim de garantir a sua utilização nas melhores condições. A irradiação é uma tecnologia capaz de descontaminar as plantas, mantendo as propriedades químicas, organoléticas, nutricionais e bioativas. Neste estudo avaliaram -se os efeitos da irradiação gama relativamente nas propriedades químicas, nutricionais e antioxidantes de várias plantas aromáticas e medicinais. Em geral, uma comparação entre as amostras não -irradiadas (controlo) e irradiadas mostrou que o tratamento por irradiação não causou alterações suficientes para definir um perfil químico específico. Assim, a irradiação gama (até 10 kGy) é uma tecnologia viável para as espécies estudadas.